New Features and Revision History

This section should be very instructive even if Version 2023, Build 1.0 is the first version you've used.

Version 2023 Build 1.0, (completed July 29, 2023) has the following changes relative to Version 2022, Build 2.0 (described below):

• The solar panel power output algorithm (in use by just a few customers at this time) has been expanded to include up to three separate panels, at different roof angles and orientations, and with different characteristics.
• Various minor cosmetic and informational changes were made, mostly in support of documenting the relatively new (less than a year old) additional of European (ECMWF) model data.
• A small bug, due to a misnamed variable in the advection mapping routine, was corrected. This would have affected only the coloring of ocean areas in parts of the Southern Hemisphere, and was discovered incidentally.
• This change was actually executed in WXSIMATE and Euromix, but affects WXSIM: it was found that an occasional ASCII character #26 (z) was appearing in some METAR data, and this was interpreted as an end of file marker, which aborted reading of further data. A cascade effect could then occur, halting euromix.exe, and wxsimate.exe, and making WXSIM’s forecasts out of date and inaccurate. This has been fixed in two ways: first, WXSIMATE now scans METAR data for such characters and replaced them with “Z” (for Zulu time), and second, if such data were to be encountered again, it would be handled by restoring the previous data file in full (so the forecast might be old, but fairly accurate).

Version 2022 Build 2.0, (December 29, 2022) had the following changes relative to Version 2022, Build 1.0 (described below):

• In the first change to the actual forecasts algorithms in years, the routine that initializes the characteristic air mass temperature, in terms of departure from normal, was modified to include a subtle effect of time of day which I’d not previously clearly identified. The problem with the previous version became apparent as I was making careful forecasts at various times of day during a very unusual cold spell, with temperatures roughly 30 Fahrenheit degrees (or 17 C) below normal. I found that forecasts made in the afternoon were a few degrees (F) colder than those made late at night or early in the morning. Careful testing showed this diurnal effect to be proportional to the departure from normal, so that in near-normal conditions it is negligible. I made appropriate adjsutemnts, which should significantly improve accuracy of afternoon and nighttime forecasts during unusually hot or cold temperatures.
• A bug (of sorts) which automatically reverted the time to the last whole hour when METAR data (but no home station data) was imported has been corrected, to allow the forecast to start with the METAR-based time.
• Related to the above, an existing option to start forecasts with the last whole-number hour – only during scheduled auto runs in which neither METAR nor local station data is found – has been continued, but is now controllable from the ‘Auto run and other settings’ form, as the second of three options; previously it was controlled through the file lasthr.txt, which is still used here, but changeable through the program. A new option has been added, to start the forecast (in either manual or auto runs) on the *closest* whole number hour (except in the period less than 30 minutes before midnight, because this would trigger a difficult to handle date change). The first, and default option, is to start with the exact minute of the METAR or local station data time, as this maximizes accuracy. The whole-hour options are for aesthetic purposes or to facilitate use with possible third party scripts. A blue-text Help item has been added for these options.
• A few formatting and wording changes were made to accommodate recent changes (plus a typo correction).

Version 2022 Build 1.0, (November 25, 2022) had the following changes relative to Version 2021, Build 1.1 (described below):

• WXSIM can now use European (ECMWF) model data, either alone or mixed with the standard GFS data. This is accomplished through changes in WXSIMATE, allowing download of certain now-freely-available ECMWF data, prepared for customized sites by Chris McMahon, in the same basic format as the existing McMahon and Bohler GFS data. WXSIM itself is changed only in having a button (‘Open euromix.exe’, on the Data Import form) for accessing the new program, euromix.exe (described in a new section, on page 49 f this manual). WXSIMATE can be set to obtain both GFS and ECMWF data, and then call on euromix.exe automatically, to mix the data according to user-defined weighting factors in euromix.exe. The only adaptation needed in WXSIM itself is to make sure the name of the file to import (generally wdata.txt) is the same as that being created by euromix.exe. This should be different from the ‘File to create’ in WXSIMATE. You might keep wdata.txt as the file to create, and then perhaps call the mixed-data file euromix.exe creates something like wdatamixed.exe, and import that into WXSIM. Euromix.exe also has a number of data visualization and analysis tools, for studying the two model outputs and their mixture.
• The main display text box on the output form has been expanded from 32 KB to 64 KB (I just learned this was possible), so twice as long a forecast can be displayed without getting the “TEXT BOX FULL” message. It should now be able to display all nine days of half-hourly output.
• WXSIM can now read 3-hourly ozone forecast values (in Dobson units) from the McMahon GFS data (possibly Bohler also at some later date). WXSIM interpolates among those to get a value at the exact forecast hour. The TEMIS (daily) ozone forecasts can still be used, as well, and if both data types are encountered, these will be averaged. This addition was prompted by difficulty downloading TEMIS data using WXSIMATE under Windows 7 (it still works fine in Windows 10), due to changes in security certificate at TEMIS.
• This change is actually in wret.exe, but is relevant to wxsim.exe: wret can now ignore dew point in its learned bias correction analysis. There are two check boxes (either of which can be used): one at the bottom of the Compare to Actuals plot form, and one on the bottom of the form were the details of the analysis appears. The motivation for this is that I was encountering intermittent outages of humidity readings on my school’s Davis Vantage II Pro station. I have since learned that I simply needed to change the backup battery, but I’ve seen bad humidity data from customers with other stations, as well, so this is a useful feature. NOTE: This option is largely redundant with the one discussed below, in Version 2017, Build 1.0, which allows WXSIM to ignore dew point (derived from relative humidity) corrections from both wret/autolearn and WXSIM-Lite. In fact, I implemented the new feature in wret (as well as a new one in WXIM-Lite) frankly having forgotten about the protection in WXSIM. I’m leaving the new ones in, however, so that the data presentations in those programs will not reflect bad humidity data.

Version 2021 Build 1.1, (completed July 5, 2021) had the following changes relative to Version 2021, Build 1.0 (described below):

• A bug, which allowed maximum or minimum temperatures from the last line in the calibration run’s output to be mistakenly recorded in latest.csv as belonging to the first line in the actual forecast output, has been corrected. Now, these temperatures are set equal to the initial temperature (as no different maximum or minimum temperatures would have had time to occur). Similar changes were made for the 1, 10, 60, and 360 minute gust speeds, setting the first line’s values to the initial wind speed.
• A bug which could cause an invalid procedure call error (#5) when GFS/READY with extreme (outside the range of -6 to +6) has been corrected.
• A bug which sometimes kept changes to the WXSIM-Lite use status from “sticking” during the current session has been fixed.
• Green (if active) status messages were added to the Output form to indicate current use of learned bias corrections and/or WXSIM-Lite data.
• The refinements with ‘Yes’ and ‘No’ buttons now light up green (instead of the previous red, which some users had interpreted as warnings) when activated. The help2.txt file has been updated with this information.
• Error handling has been improved in for the Get Data button on the Import Data form. Previously, if the supposed data file (usually wdata.txt) did not exist, the program would crash with a ‘File Not Found’ error (53). Now it advises you that the file doesn’t exist, allowing you to change the name or create that file using WXSIMATE.
• The wording of a message in wret.exe (that the site for which the forecast in the chosen .wxf file is not on file) has been clarified.

Version 2021 Build 1.0, (March 21, 2021) had the following changes relative to Version 2020, Build 1.1 (described below):

• Multiple aspects of the Anthropogenic Global Warming routine were updated after analysis of trends over the last several years, to provide a close match with trends over the last 50 years and using a mid-range projection into the future. Also, latitudinal (hemisphere-specific) and land-versus-water differences in warming rates were carefully studied and some changes made as a result. Note that all customizations are done based on 1981-2010 climate normal, and this (optional, but chosen by default upon customization, and under ‘Preferences’) is intended to maintain climate data ‘current’ over many years of use of WXSIM, without need for updating the customization itself.
• Help boxes (accessible by clicking on any of over 150 blue-text items in wxsim.exe and wret.exe) were enlarged slightly, as Windows 10 display modes sometimes clipped some of the text out.
• Messaging about missing fdata.txt was improved, including prevention of the message from stopping automated program execution.
• In wret.exe, a potential error situation is now averted, with an error message advising that a request has been made to analyze a forecast for a site not on file.
• This is not a change to any program itself, but the installation package now includes a file called latestversions.txt, listing most recent version numbers and file creation dates of all programs in the WXSIM suite. Note that changes to autolearn.exe and wxsimlite.exe are listed in readmeothers.txt, and changes to wxsimate.exe are in readmewm.txt.

Version 2020 Build 1.1, (October 27, 2020) had the following changes relative to Version 2020, Build 1.0 (described below):

• This version adds the ability to manually disable the automatic daylight saving time (DST) status detection routine. One reason for doing this would be if you simply want this ignored (not advised if your weather station data actualy does use DST). The other is that, in testing this recently across many countries with different regional Windows settings, there were some reports of it not working properly. Now, if the pop-up box advising you of a change is somehow incorrect, you can choose to disable the checking and simply control the DST status manually (with the usual check box). The routine can be re-enabled by changing the contents of nodstwarn.txt to 1.
• A bug in wret.exe, which caused it to ‘forget’ choices 16-20 of items for output in lastret.txt (in each of the two data-type sections) has been fixed.

Version 2020 Build 1.0, (July 28, 2020) had the following changes relative to Version 2019, Build 1.3 (described below):

• WXSIM (and WXSIMATE) already had routines to detect the beginning or end of Daylight Saving Time and notify the user, but these have now been improved and expanded upon, with the default now being that the setting is changed automatically (with a note to that effect). It is stil possible to override this for the duration of the current session.
• There is now consistent language across the WXSIM suite of programs for exiting the program; now all such buttons or options say lose’ or ‘Close Program’. Also, the message about not using the red Windows ‘X’ to exit has been removed for the main form, though there are still appropriate messages on other forms, telling to use the ‘OK’ button.
• Made changes to error messaging, including proper handling of an error 70 (‘Permission denied’), in which the name of the in-use (by some other program) file is given, so that you can close that file or program without ncrashing WXSIM. Other changes were made to better identify causes of other errors related to file access.
• In wret.exe, an error trap and message were added to warn the user if autolearn is trying to use data from previous years, when it doesn’t yet exist (in the file correc.txt).
• Fixed a bug which had caused an error (about omlog.txt not being open) when changes were made to Enhanced nocturnal decoupling (and possibly other otems) under Preferences/Settings.
• Problems involving the (optional) writing of latestlog.txt were corrected. The main one was that the file itself was being erased if you returned to the main Data Entry form using the ‘Repeat’ button (which is the most common method). Also, errors were possible when clicking Yes or No on a couple of the Refinement options; this has been fixed as well.
• A new (user-requested) .csv file is now made, if you are using Soil/Agricultural Data output. This file is called latestagrodata.csv (and, like other .csv files, can be archived with a date/time stamp name). The time listed in it will always correspond to the Daylight Saving Time status in WXSIM.
• A bug - which caused incorrect dates between 11 PM and midnight in the UTC time stamp (at the end of latest.csv) when DST is in use – has been fixed.
• All ouput .csv files (other than the special cases of latestshort.csv and latesagrodata.csv) now provide the option of using either the DST status in WXSIM, or the (previous default) standard time. Now, the default will be to go with what the program is using, but for legacy purposes, there is now an option on the ‘Auto run and other settings’ form to force standard time. This is Unchecked by default.
• Minor cosmetic changes were made, including removing colored borders around a few check boxes and restoring blocked edges of frames.
• A bug, which could cause a major drop in the initialized temperature and often an accompanying ‘Dew point cannot exceed temperature’ message), has been fixed. This was rarely encountered, but could result from re-running the forecast after opening the program with the ‘Recent temperatures’ refinement item in effect (colored red). I think normal operation, including refreshing the local station data import, had avoided this, but it was still possible to encounter it.
• WXSIM and wret have updated algorithms for solar radiation, now taking into account water vapor absorption (via dew point) in the near infrared, whereas I'd effectively ignored that before (it was kind of included indirectly through the auto haze, but this new formulation is better). For dew points above about 8 C (46 F), solar radiation values will be lowered just slightly (more so with increasing dew point, of course). Well below that, the WV absorption falls of more significantly, so dry winter solar irradiances will be increased noticeably.

Version 2019 Build 1.3, (completed June 15, 2019) had the following change relative to Version 2019, Build 1.2 (described below):

• By default, WXSIM will now automatically round off the current time to theprevious hour (i.e. 7:45 becomes 7:00) to initialize the forecast - IF GFS is chosen (or defaulted to due to lack of METAR, SYNOP, or local station data) as the home surface data source, AND the forecast is an auto run triggered by the scheduler (as opposed to ‘Run Immediately’ or manual operation).

Version 2019 Build 1.2, (completed June 10, 2019) had the following change relative to Version 2019, Build 1.1 (described below):

• A change was made to head off a potential error in the reading of the new GFS data, scheduled by NCEP to become active at 12Z of June 12. Testing on the parallel data has initially yielded improper reading of sea level pressure. I expect to resolve this problem before the changeover, but as a precaution, this release detects any bad pressure data and replaces it with a good estimate of that pressure, based on the 1000 mb height and other data. A similar precautionary change has been made in WXSIM-Lite.

Version 2019 Build 1.1, (completed March 6, 2019) had the following change relative to Version 2019, Build 1.0 (described below):

• A bug which could produce an overflow error (#6, in wxmain) in very rare circumstances has been fixed. This was traced to an unrealistic calculation of mixed layer height causing out-of-range large values. The maximum such height is now limited to 5000 meters (still unlikely, butnow won’t trigger an error).

Version 2019 Build 1.0, (completed January 11, 2019) has the following changes relative to Version 2018, Build 1.3 (described below):

• A new output file, latestblyr.csv, has been added, to display a variety of data related to nocturnal and capping inversions. See ‘Boundary Layer Predictions’ in section 19, above.
• Minor formatting changes were made on WXSIM’s Data Entry form, to allow display of tenths of a degree in the normal max and min temperatures for the date, and also to allow proper display of slightly longer site names.
• Minor formatting changes were made in wret.exe, to allow display of slightly longer file identifiers.

Version 2018 Build 1.3, (September 19, 2018) had the following change relative to Version 2018, Build 1.2 (described below):

• In the latestshort.csv file, the time will now be consistent with the Daylight Saving Time setting. Perviously, during DST, the date would change according to DST, but the time wouldn’t. This is still the case in latest.csv, as I did not want to “break” any scripts that might be in use, which are already adapted to this. The latestshort.csv file is actually a custom file created at the request of a single user, who also requested this change. The file is of course available to anyone who has a need for it.

Version 2018 Build 1.2, (completed August 25, 2018) had the following changes relative to Version 2018, Build 1.1 (described below):

• A problem (apparently introduced in a recent version), which casued production of unwanted .csv files (i.e. when .wxf only is checked) was corrected.
• Maximum daily solar radiation was added to the latestdaily.csv file, right before max UV, at the request of a user. Note that this is a smoothed value, so that on partly cloudy days it will “underestimate” the brief maxima which occur as the sun comes out from behind clouds.

Version 2018 Build 1.1, (completed August 5, 2018) had the following changes relative to Version 2018, Build 1.0 (described below):

• An item that was new in Build 1.0 (below), but which I forgot to list, is the “Adjust” button next to Auto Haze under Refinements on the Data Entry form. When you click this, a form appears which allows you to specify an offset for the amount of haze generated by the Auto Haze routine. The primary motivation for this is the addition of solar panel power output forecasting (described below), as this can be quite sensitive to the amount of haze.
• Changes were made in the solar panel algorithms to allow a new parameter related to the response of the panels to diffuse (scattered) versus direct sunlight. Originally, this was included as a constant, but experience with a second customer, with a different brand or type of panel showed that this can vary. Unless the new value is specified, the program defaults to the original constant.
• Another parameter was added to the solar panel algorithm: maximum inverter power. My second customer has an inverter which occasionally maxes out at a certain wattage, so I added this as an optional variable. If not specified, the inverter maximum power is assumed to be unlimited.
• A bug in Build 1.0 had caused the new wet bulb global temperature to be left blank in the first line of latest.csv. This has been corrected.
• In wret.exe, a message in Build 1.0 had pointed out the lack of Fire Weather Index in older forecast files. However, this turned out to stop execution during analysis runs (including with autoleearn.exe), so it has been removed. The default fire index for older forecast files is now set to zero, as it cannot be properly calculated from the data they contain.
• In wret.exe, the number of checked items in each section (‘Temperatures and Thickness’ and ‘Other Data’) has been increased from 15 to 20. The blue-text help items for these also now reflect these changes.
• The print option in WXSIM (‘None’, ‘Short Form’, ‘Long Form’, or ‘Graph and Summaries’) is now saved on exit.
• The latestsolardaily.csv file now outputs kilowatt-hours in the last column, instead of watt-hours. (The column heading had previously said kw-hr, so this change effectively corrects a mislabeled column heading, which itself remains as before). Also, minimum and maximum daily panel temperatures for days with insufficient data are now reported as “M” (“missing”) instead of the previous obviously erroneous defaults.

Version 2018, Build 1.0 (July 30, 2018) had the following change relative to Version 2017, Build 1.5 (described below):

• Fire weather indices have been added to the output (now under menu option #11). My research revealed two widely used and rather sophisticated indices: the Australian Forest Fire Danger Index (FFDI) and the Canadian Fire Weather Index (FWI). I was able to closely simulate both otf these, with the main difficulty being how to describe fuel moisture (but I found a reasonably accurate way, using WXSIM’s recent precipitation and other data). Each of these indices has its strengths, so I also provide the output “FWIA”, basically an average of the two, for perhaps the most useful results. This last figure is also now saved in the .wxf files, so you can view it as either text or graphics in wret.exe. Also, these indices and related data are displayed in the fire.csv fle, viewable using spreadsheet programs. More details on these indices can be found in Section XVIII of this manual.
• At the request of a customer who has a large array of solar panels installed on the roof of his home, I developed algorithms for calculating instantaneous power output and total daily energy produced by the panels. This was quite a task, as I had to develop algorithms for calculating both direct and diffuse solar radiation incident on panels of a given area and orientation (in both altitude and azimuth of the perpendicular to the array), as well as modeling the effects of temperature, variation in reflectivity with incident angle, and efficiency of the panels. The results for his panels are quite good. The data are exported in two .csv files, viewable in spreadsheet programs. Use of this feature requires customization by me, and a fee for my time developing a custom file for your particular array. Please inquire by email (eburger@aol.com) if you are interested in this.
• Wet bulb global temperature (WBGT) has been added as an output. This is a widely used index for heat stress on humans, taking into account not only temperature and humidity (as do the U.S. Heat Index and the Canadian Humidex, already output in WXSIM), but also wind and solar radiation. The definition of WGFT is 0.7 * TNWB + 0.2 * TG + 0.1 * TA, where TNWB is the “natural wet bulb temperature” – that of a thermometer covered with a white, wet, cloth, and exposed to sun and wind. With wind speeds above 3 m/s, and no direct sun, this equals the regular (psychrometric) wet bulb temperature. TG is the “globe temperature” – that of a thermometer in the center of a 15 cm diameter black-painted copper glove, exposed to wind and sun. TA is the standard (dry bulb, in shade) air temperature. There are instruments for measuring this directly, but it is very helpful to be able to calculate it from current or predicted standard meteorological data. A number of researchers have developed models for natural wet bulb or globe temperatures, or both, as described in “Calculating Workplace WBGT from Meteorological Data: A Tool for Climate Change Assessment”, by Bruno LEMKE and Tord KJELLSTROM. My algorithms start with essentially the “Bernard” equations for natural wet bulb with wind and known globe temperature, but in the absence of solar radiation. I then used samples of output the highly accurate, but very complicated Liljegren algorithms to reverse engineer the solar radiation effects on both natural wet bulb and globe temperatures, and also the wind effect on globe temperature. I made sure that my semi-empirical fits converged to known values in special cases (like at night or with 100% relative humidity). For solar radiation, I used a mix of 75% direct beam radiation and 25% global (direct and diffuse), to roughly model scattering off of (and perhaps also emission from) clouds and the ground. For wind speed, I used 60% of the 10 meter value, as the appropriate measurement height is something like 1.2 meters.

Version 2017, Build 1.5 (October 20, 2017) had the following change relative to Version 2017, Build 1.4 (described below):

• It turned out that Versions 1.2 and 1.3 had a bug, affecting only a couple of existing customers who have special mountain shading built into the customization. The changes to the eclipse routine had inadvertently disable that. This has been corrected, so eclipses and mountain shading can work simultaneously.

Version 2017, Build 1.4 (September 3, 2017) had the following changes relative to Version 2017, Build 1.3 (described below):

• Changes were made so that the latest-entered solar eclipse data is saved on program shut-down and used by default after the next boot-up.
• The warning for excessive last-30-days rainfall has been changed. This warning - the purpose of which is to tip off the user to a likely units-choice error in WXSIMATE - was previously triggered by 30 inches (762 mm) of rain for imported local data. However, at least one customer recorded over 30 inches of rain from Hurricane/Tropical Storm Harvey in the Houston, Texas area, so I have now changed the criterion to 60 inches (1524 mm).

Version 2017, Build 1.3 (August 12, 2017) had the following changes relative to Version 2017, Build 1.2 (described below):

• In light of my discovery that the GFS model apparently does NOT take eclipses into account (I cannot see, in a couple of forecasts near the path of totality, dips in either temperature or downward shortwave radiation flux in the three hourly data which would suggest that), I have made the WXSIM-Lite mix routine ignore GFS 2-meter temperature data (via fdata.txt) during the eclipse. There will still be a slight residual GFS influence, via upper air temperatures, advection, and the return to full usage of the mix after the eclipse is over, but the temperature dip should be more realistic, and almost as great as without use of any external data.
• Through investigating acorrec.txt file from an autolearn use, I discovered that the connection between autolearn.exe and wret.exe, when using the last two years of data option in autolearn, was failing for sites where commas are used as decimal separators. The main problem with this was too large of a diurnal range of temperature in the resulting forecasts. I have now fixed this, but you must simultaneously upgrade to autolearn.exe 3.6 and wret.exe 2017, Build 1.3, as neither will be compatible with older versions of the other. Both of these new versions are in the WXSIM 2017, Build 1.3 upgrade (and demo).

Version 2017, Build 1.2, (July 30, 2017) had the following changes relative to Version 2017, Build 1.1 (described below):

• The solar eclipse form was changed so that the actual month, day, and year of the eclipse are entered instead of the previous method of giving the number of days into the forecast. This way, the form does not need to be updated daily as it was before for an approaching eclipse.
• The eclipse data is now stored in an external file called ecdata.txt, so that if the program is closed it can still 'remember' the eclipse on boot-up. Also, a third button for accessing this form was added, to the Auto Run and Other Settings form (it is also accessible from the Interrupt Planner and from tab 1 under Preferences).

Version 2017, Build 1.1, was completed May 15, 2017 and has the following changes relative to Version 2017, Build 1.0 (described below):

• Data types were added in the cty.fdt file to enable more versatility with wind speed forecasts for wind turbines (typically between 40 and 80 meters above the surface). The wind behavior can now be made even more site-specific than before (allowing for a range of surface roughness and inversion-proneness) and also can now supply winds at two heights (one half that of the other, customized one). Note that this feature is available only if it was included in the customization.
• wret.exe can now handle a change in file names in CumulusMX, where (at elast under Spanish settings) a period now appears after the month abbreviation. WXSIMATE and WXSIM-Lite also had changes allowing for this. In each case the name change is auto-detected, so no user action is required.

ADDITIONAL NOTE: Occasionally users may encounter Permission Denied (VB error number 70) errors, which shut down the program. I declined to attempt anticipating all such errors in my error trapping code, out of concern about interfering with other error trapping routines. The cause is usually very simple: a WXSIM file is being used by another process, which CAN be another program in the suite (i.e. WXSIMATE), if that programs gets stalled somehow or is scheduled to run overlapping with WXSIM. Another cause of the problem could be if the user has opened a file such as latest.csv or latestturbine.csv for viewing in Excel, and left that open. Being alert to these possibilities will likely prevent the error from ever appearing, or at least make it fairly easy to fix if it ever does.

Version 2017 (Build 1.0, February 18, 2017) had the following changes relative to Version 2016, Build 1.2 (described below):

• Added the ability to customize shadowing by mountains, and effects of sloped terrain in general (on solar radiation)
• Fixed a bug which on rare occasions caused the date to revert to the start date during the forecast (I think only one user ever reported this, but I was able to reproduce and fix the problem)
• Added an option (under Start/Auto run and Other Settings) to omit humidity (dew point) bias and WXSIM-Lite corrections, which keeping all the temeprature stuff. This was mainly motivated by one user whose station's hygrometer totally failed, but I've seen other questionable humidity data in users' files before, so this may have some wider application.
• Created WRETMATE, a companion program (openable either alone or via buttons in wret.exe, autolearn.exe, or wxsimlite.exe) which allows you to easily manage the large number of old forecast (.wxf) files which can acculate over time and potentially make WXSIM-Lite or WRET/Autolearn rather slow in completing their analyses for bias corrections ("learning"). This new program allows you to (reversibly quarantine archived forecasts that are too old or have non-standard names. It also lets you randomly cull the list of forecasts down by a percentage of your choice (i.e. if you were making forecasts every hour, you could trim the analysis set down to, say, an average of 5 per day, for quicker processing).

(Note: Version 2016, Build 1.3 was experimental and not officially distributed).

Version 2016 (Build 1.2, June 15, 2016) had the following changes relative to Version 2016, Build 1.1 (described below):

• A new bug (a division by zero error) had resulted from fix #3 in Build 1.1 (below), for users having selected the (mostly used in Canada) humidex option. This has now been fixed.
• Protection was added against older version's customized files producing an invalid property value error in the GFS upper air temperature bias settng when used with the new version. I had not actually had reports of this, but ran across it while experimenting with older files to find the problem in #1.
  

Version 2016 (Build 1.0, June 14, 2016) had the following changes relative to Version 2016, Build 1.0 (described below):

• In WXSIM, there were sporadic reports of "No READY or GFS data found". In some cases, at least, this was actually not "true"; data WERE found, but were judged to be "unbelievable". Specifically, every now and then GFS reports a relative humidity lower than 1%. I did have a filter to reject anything that low or lower, but have now eased up on the restriction, so WXSIM will "believe" values as low as 0.01%. These very low RH's seem to happen only in upper levels of the atmosphere, so they really won't hurt the surface forecast, anyway.
• In wret.exe, a couple of people recently reported an error #9 (subscript out of range). I found this to be because these users had 10,000 or more forecasts archived! I had not considered that large of a number when dimensioning arrays (up to 9999), but in fact people running close to 20 forecasts a day for a year and half can indeed collect that many! That's frankly too many for wret.exe/autolearn to use anyway, so the oldest forecasts (.wxf) should be placed in another folder for safekeeping. However, I don't want users to ever have to see the error, so I've "pre-empted" it, by checking the numebr of forecasts before the error gets a chance to occur. Now a message box appears, instructing the user to get the number down under 10,000 by moving the older forecasts to another folder.
• Protections were added in the functions calculating dew point from vapor pressure, and dew point from temperature and relative humidity, in order to handle entered or imported relative humidity values of zero.
  

Version 2016 (Build 1.0, March 29, 2016) had the following changes relative to Version 2015, Build 2.1 (described below):

• A bug, which reversed the sign of 'residual' corrections to minimum temperatures when using WXSIM-Lite, was corrected. The errors were usually only a few tenths of a degree, but in rare cases could be large enough to make the 'minimum' higher than the lowest output temperature.
• Modifications were made to the way WXSIM uses learned bias corrections from cor.txt (i.e. created via autolearn.exe) along with WXSIM-Lite data, so that out-of-range values are not only limited, but the values to be written into .wxf files are made so that they would not have led to limit exceedence in the first place.
• WXSIM now modifies ingested WXSIM-Lite data by taking the values from fdata.txt and applying a climatological filter, to weakly trend GFS-derived temperatures and dew points toward seasonal normals.
• Changes were made in wret.exe to modify values from previously used correction factors if these were determined using earlier versions of WXSIM. This is because a study of about 20 sites' correction factors with and without autolearn showed biases due to items 1 through 3, above.
• wret.exe was changed to allow incorporation of learned bias corrections from the same season as present, from one and two years ago, as analyzed by autolearn using correc.txt. These data are also adjusted if they come from periods when an earlier version of WXSIM was used with WXSIM-Lite (i.e. before this current release date, or more specifically February 20, 2016, when the first beta version was released).
• The checks for lines of bad GFS data, for both home site and advection, were made much more robust to shield against implausible (and often error-producing) values being imported into WXSIM. These bad values have been very rare - usually only one error in 81 lines of data if they happen at all - and are almost never on consecutive lines, so the algorithms here replace bad values with ones interpolated from before and after the line with errors. One error in a line is deemed reason enough to replace ther whole line.
• An error message in wret.exe, which could result from a corrupt .wxf file, was enhanced with instructions about how to correct the problem.
• An option (during customization, so this will not affect existing jobs, unless I custom add the feature to your cty.fdt file) has been added to model the effect of sloped terrain, so that solar energy absorbed by the surface takes this into account. Along with this, shading from mountains (usually just after sunrise or before sunset) is enabled, with two "mountains" (and "eastern" one and a "western" one) specifiable. WXSIM tracks solar altitude and azimuth, and can now "eclipse" the sun at the appropriate times.
• More information was added to a number of error and irregularity messages (especially the ones reported by wxerr.exe after a WXSIM run completes), in order to help the user diagnose the problem.
• Information was added to the prompt which appears when the DST (Daylight Saving Time) box is changed. This prompt offers the opportunity to make the similar settings in wret.exe and wxsimate.exe the same as in wxsim.exe. However, this change takes effect only if those programs are closed, as the prompt now indicates. (This setting can be changed independently in all three programs anyway).

Version 2015 (Build 2.1, completed November 3, 2015) has the following changes relative to Version 2015, Build 2.0 (described below):

• Options for customization were added to enable automatic elevation-based adjustment for the 'home' METAR and (separately) SYNOP sites' imported temperature and dew point values. This does not affect customers who ordered before October 24, 2015 and will not often be used in customizations. The purpose of these additions is to enabled users in mountainous areas, *without* home weather stations, to get useful initial surface conditions from METAR or SYNOP import.
  

Version 2015 (Build 2.0, completed August 8, 2015) had the following changes relative to Version 2015, Build 1.3 (described below):

• A safeguard was added (actually, it had been accidentally disabled in some earlier version) to avoid forecast errors which could result from use of a too-small set of historical data when using the learning routine (in autolearn or wret) in conjunction with WXSIM-Lite.
• The enhanced nocturnal decoupling routine (mainly useful for medium-large islands, such as New Zealand) has been modified, making it slightly stronger (hence colder nighttime lows in clear, calm conditions) but also phasing it in and out with the seasons, as it is needed primarily in winter.
• A warning message was added, if WXSIM imports local station data showing more than 30 inches (762 mm) of precipitation in the last 30 days, which is a likely consequence of choosing inches as the units in Weather Display or Cumuls log files, when in fact they are being recorded in millimeters, in WXSIMATE.
• wret.exe can now function with autolearn via WXSIMPRO (theoptional multi-sitecontroller program), so that separate learned bias correction factors can beautomatically determined for each site.

Version 2015 (Build 1.3, March 10, 2015) had the following changes relative to Version 2015, Build 1.2 (described below):

• Air density at turbine height was added as a variable to latestturbine.csv (a file produced only for sites customized for wind turbine predictions).

Version 2015 (Build 1.2, March 10, 2015) had the following changes relative to Version 2015, Build 1.1 (described below):

• Better error trapping was added to prevent users from attempting forecast runs using WXSIM-Lite data, if WXSIM-Lite has not yet been used to produce a forecast.
• A very rare error, which could produce an 'Invalid property value' error at the very end of a forecast run, has been addressed and probably corrected (according to initial tests from the users reporting the error). This resulted from occasional spurious attempts to open the advection form at or near the end of a forecast run. While the exact cause of this has not been identified, the protection consists of having the form unload itself if activated after 98% of the forecast run is complete. A log file called adv_activate_error_log is now created to document occasions on which this protection is called upon, even when the error is successfully avoided.
• The default bias corrections to GFS data on the 4th tab under Preferences/Settings have been changed to neutral values, presuming that the new 0.25 degree GFS data has no known temperature, cloudiness, or precipitation biases.
• The data retrieval program, wret.exe, now has a more informative message when it traps errors due to misplaced data in log files (such as from Weather Display).
  

Version 2015 (Build 1.1, January 2, 2015) had the following changes relative to Version 2015, Build 1.0 (described below):

• Better error trapping was added to prevent users from attempting forecast runs using WXSIM-Lite data, if WXSIM-Lite has not yet been used to produce a forecast.
• A very rare error, which could produce an 'Invalid property value' error at the very end of a forecast run, has been addressed and probably corrected (according to initial tests from the user reporting the error)
  

Version 2015 (Build 1.0, December 31, 2014) had the following changes relative to version 12.12.1 (described below):

• First, a new naming convention has been adopted, using build numbers and major release years, starting with 2015 being released just prior to that year.
• Most importantly, WXSIM has been modified to use data from the new companion program, WXSIM-Lite. That program (included in the WXSIM installation and upgrade packages) makes forecasts using a different approach, in which GFS (and later perhaps additional model data) is downloaded, adjusted and interpolated in various ways, and then saved for later comparison to actual data from a personal weather station. WXSIM-Lite can then analyze the results to build a sophisticated set of bias corrections to apply to future forecasts, somewhat like WXSIM's own 'learning' routine. Months of testing have shown WXSIM-Lite's temperature forecasts to be generally more accurate - by about 15 percent, and maybe more for some sites - than WXSIM's own forecasts. However, data also suggest that WXSIM's forecasts have indepent value, especially for short term and nighttime forecasts, so the potential exists for mixing of WXSIM and WXSIM-Lite forecasts to produce forecasts better than either alone (though only a bit better than WXSIM-Lite's forecasts). This new version of WXSIM allows WXSIM-Lite's temperature and dew point forecasts to influence WXSIM's output to a user-specificied extent. This is almost sure to produce the biggest single improvement in WXSIM's accuracy in many years. It is possible (and advantantageous) to use WXSIM's own learning feature concurrently with incorporation of WXSIM'Lite's data. Information is stored in WXSIM's forecasts to indicate the extent to which WXSIM-Lite's data was mixed in, and this information is carefully taken into account in later use of learned bias corrections. In other words, both programs can 'learn' at the same time without conflict or any need of second-guessing on the part of the user.
• IMPORTANT NOTES: The ability to mix in WXSIM-Lite data is available in WXSIM's professional mode only. Also, the current plan is for WXSIM-Lite's special data to become subscription only (at a very low rate, but enough to cover server and ongoing development costs) at a later date, perhaps in late February, 2015. Meanwhile, the data are temporarily free of charge.
• The Auto Run form under the Start menu item has been expanded and organized (and renamed as 'Auto Run and Other Settings'), and now includes access to the form for mixing in WXSIM-Lite data and also control over end-of-forecast settings formerly accessible only (and perhaps inconveniently) on the Output form.
• A new option to alter the appearance of WXSIM's main programs has been added (button on the new 'Auto Run and Other Settings' form). This allows use of 'XP and later Windows Styles', if you are using Windows 7 or later (it actually causes some bad display of option buttons in XP itself). You can toggle back and forth between the style options to see what you like best.
• Various cosmetic and informational changes were made, including a new color scheme for WXSIM's Data Entry form.
• Potential use of imported GFS data has been expanded to include up to 9 days of data (the maximum length of a WXSIM forecast), instead of the previous 7.5 day maximum. This will become relevant when the GFS data downloaded by WXSIMATE is changed over to the upcoming 0.25 degree resolution version. The implementation date of this is uncertain as of this writing, but hopefully will be done by sometime in February, 2015.
• Wording of the convective bulletins about 'Showers unlikely' and 'Showers very unlikely' has been changed by adding the word 'Convective', so that contradictory-looking text about showers being unlikely while (stable) rain is forecast will no longer appear.
• The autolearn.exe program has been updated to version 2.0, which allows graphs of the history from correc.txt
• The Daylight Saving Time setting (always a pain in the past, I know) is a bit simpler now. When you change the check box in WXSIM, it should make the same change in wret.exe and wxsimate.exe as well (that does not work in reverse, though). I do have a "warning" system in place, which looks for evidence that the setting does not go with the computer's clock. It's still a bit complicated, though, because there are reasons (at least for me) to alter the setting (for example, in wret.exe, if I'm analyzing old forecasts from another season). So, the change is not made automatically. However, it should warn you (at least the first time DST status changes) and you can now make the change globally.
• A small bug was fixed: at the beginning of the forecast, the advection routine was displaying (though apparently not actually using) a "normal" temperature (for the time and date), instead of the actual temperature, as the "home" temperature, against which actual upwind temperatures are compared to generate an advection profile. This has been corrected so that the actual temperature at the time is displayed.
  

Version 12.12.1 (May 3, 2014) had the following changes relative to Version 12.12 (described below):

• The ability to forecast wind speeds at specified heights above the ground, for use in forecasting wind turbine power output, was added. This additional data is displayed, along with other relevant data, in a new output file called latestturbine.csv. This feature is not generally available to all users, but is something I can customize specifically for the site, based on turbine height, surface roughness, and (optionally) past wind history.
• Warnings and measures have been added to wret.exe to prevent users from trying to use 'combined' data in the analysis for learned bias corrections. The purpose of the 'Combine' box on the comparison to actuals graph is to allow display of hourly-averaged data, not to develop correction factors.
• A bug in wret.exe, which could cause an 'Invalid procedure call' error, has been corrected.
• Another bug in wret.exe, which occasionally and mistakenly caused rejection of data (for developing learned bias corrections) has been corrected. This was a simply typographical error in a variable name in my code.
• wret.exe now is able to circumvent a problem involving reading of WeatherLink data. It seems that occasionally, the first couple days of the month (for one user, anyway) have some garbled data, either due to the .wlk files themselves, or perhaps to WXSIMATE's interpretation of that data (which is binary "gobble-dee-gook"). It now skips over such stuff until it find reliable data and uses only that. This affects the autolearn and Auto Select routines, but again, only if you are using WeatherLink.
• wxsim.exe has a change which should have no effect whatsoever on any existing customization. This is a customizable feature controlling the extent of mixing in light winds under strong inversions, primarily in arctic regions. Generally, the problem (based on data from a site in Yukon, Canada) was that such mixing was too weak, and this change makes it possible for me to strengthn it, if needed, in customizing.
• An erroneous message telling the user to uncheck the 'Run optional DOS batch file' (when it was in fact not checked) in WXSIM has been corrected. Actually, I am not sure if this bug was present in the official version 12.12, or if it was only in a beta version since then. Either way, it is now corrected.
• A rarely occurring, but longstanding (several years!) error #6 ('overflow') in both wxsim.exe and wret.exe has been solved. This error occurred when the 'Shell' command was called to open another program (such as wxsim.exe opening wret.exe at the end of a forecast). I finally discovered that it was a case of my having declared the 'task number' to be an integer, but occasionally, on some computers, the system would assign a number bigger than 32767, which is the highest integer allowed. I have now declared this variable as 'double precision', which should totally sove this problem.
  

Version 12.12 (February 5, 2014) hadthe following changes relative to Version 12.11 (described below):

• A more sophisticated treatment of the learned bias corrections has been implemented. This modifies the "slope bias correction" in such a way that there is a smooth tail-off in the effect when departures from normal temperature are greater than the average amount of departure from normal in the analysis. Something like this existed in previous version, but the function was discontinuous in slope and did not reduce the bias sufficiently. This one reduces it to about a third of the "learned" value when departures are more than about twice the average amount of departure. Also, a very thorough statistical analysis of thousands of forecasts, combined with studies using randomly generated data in Excel, suggested that extending small sample sizes of data to a larger range of conditions presents a problem: part of the error in error versus forecast departure from normal is an artifact of using (necessarily) the forecast departure as a basis, instead of the actual departure as a basis. Essentially, a too-warm forecast also tends to be an "above normal" forecast. I have now standardized the slope to be defined as appropriate when standard deviation of departure from normal is twice the standard deviation of the error itself. Outside this range, the slope is altered towards being a bit more "extreme" (allowing greater departures from normal). I believe this change will allow better transition between seasons, for instance by anticipating the possibility of larger temperature excursions in the fall, after a monotonous summer.
• Changes were made in wret.exe to the plots of error versus date and versus departure from normal, to increase readability and reflect the changes listed in (1), above.
• Bitmap plots, named errdate.bmp and errdep.bmp, are now made when the plots mentioned in (2) above are viewed, or when autolearn.exe completes its run of wret.exe.
• The default "distance ratio" on the advection form was reduced from 1.15 to 1.1, as this now appears to make more accurate fits for upwind advection profiles.
• An occasional overflow error (Visual Basic error number 6) resulting from the use of the Cint function in Visual Basic, with values over 32,767, was corrected by using Int(x+.5) instead. This error may have existed for a long time, but the change in the distance ration from 1.15 to 1.1 may have made it more likely to show up.
• A routine intended to better model mixing out of morning temperature inversions was found to have bad effects (a brief dip in temperature around noon) on cloudy days with light winds, mainly in winter at high latitudes. This has been corrected by phasing the effect out as cloud cover increases.
• Changes were made to hopefully avert a rare printer error in cases when no printing was requested.
• Changes were made to slightly reduce the diurnal temperature range and also the rate of air mass modification in colder than normal weather. This was based on careful study and re-running of forecasts of historical data, mainly during arctic air outbreaks.
• A sort of climatological filtering has been applied when GFS model data is being used, so that temperatures past about 2 days into the forecast are trended slightly towards normal. This "correction" is actually only about half the theoretically optimum value, so as to preserve some of the underlying run-to-run variability, but still tone down unrealistic extremes which crop up at times. The treatment is season and location specific, by taking into consideration typical standard deviation of error in GFS data along with typical standard deviation of actual temperature.
• Maximum daily snow depth was added (to the existing average daily snow depth) in the Supplemental Dat section in the scrolling text output and in latest.txt.
• Internal changes were made in the main forecast module to allow room for the additional code.
• The learned bias corrections displayed under Preferences/Settings in WXSIM are now in familiar units (i.e. degrees F or C) instead of the cryptic raw values diplsayed in previous versions.
• A failure to clear out old data had sometimes caused brief (only in the first three hours or less of the forecast) excursions, mainly in barometric pressure, when using GFS data. This has been corrected.
• A very slight increase in the weighting of the "clear thickness maxiumum" (an estimate of clear sky maximum temperature based on the thickness of the lowest 130 millibars or so of the atmosphere) was made, so that daily maximum temperatures will be constrained slightly (a couple of tenths of a degree, typically) closer to this figure.
  

Version 12.11 (January 1, 2014) had the following changes relative to Version 12.10.2 (described below):

• An oversight in wret.exe caused (only for users of Cumulus) the ‘Comparison to Actuals’, as well as the learning routines (through Auto Select or autolearn.exe) to jump back to January, 2013 after December 31, 2013, instead of proceeding to January, 2014. This has been corrected. Since the change involves only wret.exe and the official selease was just yesterday, I am simply repackaging the installer with this change, rather than renaming the entire version.
• Options for sea surface temperature on the Diurnal Breeze form were made more simple and explicit. There are now option buttons for either using default sea temperatures or user-entered ones. These settings take effect as soon as the OK button is pressed, and are saved for future runs until changed.
• The default (climatological) sea temperature now changes with each day of the forecast, rather than retaining the value from the first day.
• A typographical error in a warning about far-from-normal sea surface temperatures was corrected: "10.8" Celsius was changed to "6" Celsius.
• Messages about missing local calibration data (from localcal.txt) are now deferred to the auxiliary external messaging program (wxerr.exe) so that they will not interrupt auto runs.
• The 'Offset' and 'Range' factors in WXSIM were previously simply stored values which the user needed to keep consistent with 'Dep' and 'Rng' in wret.exe (which are used in developing learned bias correction factors through Auto Select or autolearn.exe). They were not - and still are not - used in any way in generating a forecast, but are written into latest.wxf as a record of the user's intent in wret.exe at the time of the forecast. Changes have been made so that the values shown are read, both at forecast time and when the form is opened, from wret.exe's initialization file, retini.txt. Also, the boxes displaying the two values in WXSIM are now disabled for user modification, since they need to be enetered in wret.exe to be used.
• An unused form (gfsadj, whose functions were incorporated into the tabbed form under Preferences/Settings several versions ago) was deleted to reduce program size.
• Error trapping was improved in wret.exe to avoid crashes when latest.wxf is not found.
• Changes were made in the auto select ("learning") routine of wret.exe to avoid a "file already open" error that was reported by two users.
• Error trapping was improved in wret.exe's comparison to actuals and learning routines, by displaying the last line read from a potentially faulty weather station software log file in the error message. This allows the user to quickly find and correct the problem in the log file. The example motivating this change was a case of a few dates being out of order in a Weather Display log file, which caused a 'Subscript out of range' error in wret.exe.
• Minor cosmetic changes were made in wret.exe.
• Appropriate changes were made to WXSIM's blue-text help file.
• A bug which allowed the year to remain the same in .csv files, when January 1 is reached, was fixed. The change also applies to other routines which are functions of the year, such as climate and solar forcings.
• A bug similar to that above, involving the UTC time stamp in the lastret.txt file, was fixed in wret.exe. This also now has correct output across the change to the new year.
• In wret.exe, bitmap graphics are now automatically produced for the error as function of date and of departure from normal graphs when these are displayed. Also, these are briefly displayed, closed, and graphics created auto,atically by autolearn.exe when that program is used.
• Small wording changes were made in the output of wret.exe's auto select learning routine.
• Small changes were made in the advection form's output for quality of the curvature fit. Previously, erroneous values for "Spd" and "%" were briefly shown (but not actually used in the final fit). Also, the advection site map now shows the number of sites actually used for the fit rather than the total number found.
• On the data import form, the number of sites found for advection was sometimes shown too large by one (when MOS runs out and the program defaults to GFS). This has been corrected.
• A warning message now appears in WXSIM if the status of the DST (Daylight Saving Time) box does not match the status derived from internal data for the computer (derived from a comparison of the GMT system time and the adjusted time on the computer's clock, considering WXSIM's time zone information for the site). This message occurs only at start-up of WXSIM (as an internal message box) or in auto run at the end of a forecast (as an external message box which does not interfere with the forecast). There may be some users who run forecasts for sites outside of the computer's time zone. To accommodate this, there is an option to prevent the message from appearing after the first time.
• A possible fix to a problem involving a rare problem of failing to get fresh GFS data on the first run of the day has been implemented. Actually, the code for this fix existed in the last two versions, but was probably ineffective because a variable had not been declared globally; now it has.
• Small cosmetic changes were made to a couple of forms.

Version 12.10.2, (September 23, 2013) had the following changes relative to Version 12.10.1 (described below):

• One or more causes of an occasional error 52 (bad file name or number) were corrected. As of this writing, such an error is being reported by only one user, with the cause seemingly something very system-dependent. If such an error is still encountered, two possible workarounds are UNchecking 'Minimize forms', CHECKING 'Omit log files' (both these on the Auto Run form), or (an almost certain fix) having WXSIM close after auto runs, and be reopened by a third-party scheduler.
• Wording was improved to be more instructive in the case of messages about not not having imported model data.
• A bug which often caused failure to use local station data in the calibration run was corrected. A separate, but related error was fixed in WXSIMATE as of version 5.3.2, completely correcting this type of error (which had only very minor effects on most forecasts).
• Autolearn.exe has been updated (now version 1.2) to improve clarity of use and avoid common user mistakes in connection with wret.exe, which also had small improvements in wording.
• wret.exe now formats correc.txt properly even with regional and language settings using commas as decimal separators (previously older data was split awkwardly into multiple lines).

Version 12.10.1 (August 16, 2013) had the following changes relative to Version 12.10 (described below):

• A new program called AutoLearn has been added to the WXSIM suite. It allows scheduling of automated "learning" runs (for use in WXSIM's Professional Mode) by wret.exe, and changes were made in wret.exe to accommodate this. AutoLearn is actually a separate program, with a registration fee for full-featured use. In demo mode, it has a fixed 10 day analysis period, which is too short for optimal results, but can still give users a good look at how it works. Note that this is for convenience only, as manual use of the AutoSelect feature in wret.exe accomplishes the same task.
• WXSIM's response to the learned bias correction factors has been fine-tuned. Testing revealed that, under normal use (including GFS and FOUS data and advection), the overall temperature correction and the "slope" parameter supplied only just over half the needed correction on the first try, so that a period of time two or three times the analysis period (which is often months) would be needed for essentially full response, by which time short-term and even seasonal effects would be largely blurred out. The range and dew point factors were fairly well-tuned already, but all four parameters have now been carefully adjusted to yield full response on the first use, with or without GFS, FOUS, or advection data.
• The range of allowed values in the 'slope' correction factor (which influences the 'pull' towards climatological normal temperatures) has been expanded to +/- 40% (instead of the previous 25%), in light of data which showed these more extrme settings are sometimes needed. However, this usually occurs in rather monotonous weather with few air mass changes, and extrapolation to more extreme temperature events may not be warranted. For this reason, the slope factor now contains information about the range of departures from normal in the anaylsis, and WXSIM uses this to reduce the effect to no more than +/-20% for temperatures well outside this range, smoothly transitioning to this figure with increasing departure from normal.
• Minor informational and cosmetic changes were made in both WXSIM and wret.exe. These include parenthetical information in WXSIM's File menu that retrieving data means opening wret.exe, and that the Cull/Append routine is seldom used. In wret.exe, departure from normal is now shown to be an 80%/20% mix of forecast and actual values (in that order, and as they have been for some time) and instead of average forecast and actual departure from normal, the mean values for the cooler and warmer halves of this 80:20 mix are shown.
• Clicking the 'Cumulus' option on the Comparison to Actuals form now enables entry of text, regardless of prior choice (previously, it was necessary to have checked Weather Display first - an oversight in the implementation of Cumulus use for this.
• It was found that, under certain scheduling conditions, auto run could generate messages that the data were over 24 hours old, on the first run of the day. This also significantly impacted the accuracy of those forecasts. Changes have now been made so that this error should no longer occur (though the message should still appear if the data actually ARE over 24 hours old).
• I discovered (in studying Finnish users' data) an odd shape to the diurnal temperature curve in the May-July period. The temperature would rise quickly in the morning, then warm almost linearly until a somewhat too-late high temperature (about an hour or two later than reality). I traced this to an oversight in a very old routine which estimates the times of day when the temperature should be near the daily mean, as these figures help inform the onset of mixing with daytime heating. I apparently had not tested this at these latitudes near the solstice, so the problem has been there a long time! This has now been fixed. The change to wxsim.exe is significant if you live more than 45 degrees from the equator and are having daylight exceeding 15 hours, the difference being very minor until you reach about 60 degrees latitude, but very important near and north of the arctic circle.
• There is now a trap set for errors at the end of an auto run run, at the point where WXSIM attempts to boot wret.exe to make graphics and the lastret.txt file. Such errors have been elusive as they seem to be sensitive to other processes on the computer, because rebooting would sometimes prevent the problems (which tended to be intermittent anyway). It should catch any error #6 (overflow) errors and just act like nothing happened (which I think will be OK). It might catch others, too, with a message, and then hopefully keep going. This error may have also led to bad .wxf files and errors in wret.exe. Incidentally, such errors were the reason for the 'Ext boot' option (check box near the 'Graphic' check box on the Output form). This option remains, just in case it's still ever needed.
• A change was made which should prevent a certain 'file already open' error.
• The document 'Evaluating Temperature Forecast Accuracy in WXSIM'(written on July 6, so that some of the screen shots are very slightly outdated) was made part of the standard WXSIM distribution package.
  

Version 12.10 (June 30, 2013) had the following changes relative to Version 12.9 (described below):

• The sea breeze routine's warning system for abnormal sea surface temperatures has been changed so that only discrepancies larger than 6 Celsius degrees (10.8 Fahrensheit degrees) will trigger a message that actually interrupts program execution. Discrepanices greater than 3 Celsius degrees (5.4 Fahrenheit degrees), but no more than 6 C will now trigger only an external message which does not interrupt the program. Discrepancies larger than 1.5 degrees will be recorded in the file seatempanomalies.txt.
• Sea level equivalent water temperature, and also normal default values for water temperature and its sea level equivalent are now displayed on the diurnal breeze form.
• Small informational and cosmetic changes were made to the Save Data form.
• Internal changes were made regarding the reading of registration codes.
• A bug in the soil data routine, which sometimes caused it to fail to read station data (especially when less than four depths are used and blanks instead of "999" were entered in WXSIMATE) was corrected. Slight changes in the extrapolation of moisture to non-measured depths were made also.
• A message was added to WXSIM's Soil Data Entry form to prevent users from checking more than 5 agricultural output variables (though all variables are saved for later viewing in wret.exe).
• Changes were made to the way in which layer relative humidities from NAM FOUS data (North American users only) are interpreted as cloud cover. In particular, extensive research showed that, with steep lapse rates (such as in summer), higher relative humidities are needed to produce overcast conditions (perhaps because areas of downdrafts produce clearer patches) in levels 2 and 3. The main effect of this change is that some overcast or mostly cloudy summer forecasts will now be mostly or partly cloudy instead.
• It was found that - when FOUS and READY or GFS data were used together - the averaging was (inappropriately) somewhat dependent on the time interval (a function of the output interval and the number if iterations per interval). Changes were made in the way FOUS influences cloud cover and precipitation, so that these discrepancies are reduced to a trivial level, especially if the time interval is kept to 10 minutes or (preferably) less. This occurs, for example, with an output interval of 30 minutes and 3 iterations per interval (while 6 would be better, for a 5 minute interval).
• An internal typographical error in WXSIM, which could have (but probably never did) affected sunset times in unusual circumstances, was corrected.
• Comparison to actuals is now avaiable in wret.exe for Cumulus. This also makes it possible to use (in professional mode) the "learning" routine with Cumulus.
• Informational changes (an extra decimal place, number of forecasts analyzed, time to complete the run, etc.) were made to the Auto Select results in wret.exe.
• Major improvements were made to wret.exe's Comparison to Actuals and Auto Select routines. A wealth of statistical data is (optionally) displayed, both graphically and as text on the comparison graphs. These include not only net and mean absolute errors, but root-mean-square errors and standard deviation of error, as averages over periods ranging from a day to 30 minutes.
• More information was added to the Auto Select output in wret.exe, such as indicators of four different types of reasons for data rejection, and user input regarding criteria for rejection. Also, message boxes have been added for guidance in the use of this routine.
• A UTC date/time stamp was added to the end of each line of data in lastret.txt (produced by wret.exe), mainly to help developers of php scripts for displaying WXSIM forecast data graphically.
• Minor formatting changes were made to lastret.txt's output, including a one decimal place (instead of a whole number) for sea level pressure in millibars (hectopascals) and an extra space in front of lifting condensation level if its value reaches or exceeds 10,000 (this should happen only if using feet as units).
• Error handling has been improved in wret.exe, so that when it encounters a corrupt forecast file (caused by improper closure of WXSIM - by the user, due to an error, or due to a power outage), it advises the user of the reason for the error and gives instructions for how to remedy it (previously it just gave an error message and crashed the program).
• Very minor cosmetic and informational changes (i.e. punctuation and spelling) were made to both wret.exe and wxsim.exe.
  

Version 12.9 (March 4, 2013) had the following changes relative to Version 12.8.11 (described below):

• A protection has been added to handle the possibility of the site specified in custinit.txt not having corresponding METAR code and name with any site in cty.fdt. Previously, error messages such as "Dew point cannot exceed temperature" may have appeared in such cases (which would be extremely rare, indicating probably file corruption).
• The messages "Dew point cannot exceed temperature" and "Unrealistic barometric pressure" are now skipped in auto run mode, while the dew point is quietly set to the temperature and the barometric pressure to the world-wide sea level mean. These changes also occur even if the messages do appear (in manual mode).
• The routine for writing the latest.csv file was inappropriately combining weather types 1 and 2 and writing this as type 1 (while correctly writing type 2). This has been corrected.
• A check on program startup (upon loading site data) has been added to see if the computer uses commas as a decimal separator. If so, the setting 'Use semicolons for .csv files' defaults to true (checked, on the Auto Run form) in order to avoid errors in the writing of the .csv files.
• The function for calculating distance to the sun was fine-tuned, yielding a slightly smaller difference between perihelion and aphelion and a shift of a bit less than a day. The maximum effect on solar radiation is at the surface is no more than as 3 watts per square meter, and resulting temperature effects in the program are on the order of a tenth of a degree. The main reason for the change was to make solar radiation outputs as accurate as possible. Also, I did a fresh study of the solar radiation model, and found that the only changes appropriate were the above.
• A carefully devised function for the 11 year solar irradiance cycle was constructed, including an assumption that over the next cycle or two, the sun may enter a relatively quiet phase, perhaps approaching that of the Dalton minimum in the early 1800's. The peak-to-valley variation of about 1 watt per square meter is assumed to decrease to about 0.7 w/m^2, with a drop in the average by about 1 W/m^2. I assumed (with little basis, other than comparison to the Dalton and Maunder minima) that this dip may last about 50 years. Actually, direct effects of this on temperature are trivial (on the order of a tenth of a degree) compared to other sources of error. I mainly included it in case it is of further interest later.
• The "use global warming" option has been updated, based on a recent (last 12 years or more) leveling-off of the previously rising global mean temperature. This "flat" stretch is documented in both the NASA GISTEMP and Hadley Center HADCRUT data. It may be partially explained by recent small decreases in solar activity, both as part of the normal cycle and changes in the cycle itself. To incorporate this, I applied the solar cycle model described in (6), and also applied a gentle concave up curvature whereas earlier I had it linear. It still produces about 3 Celsius degrees of warming between 1965 and 2100, but with only a slight rise before 2020.
• This is really an addition to WXSIMATE, not WXSIM per se, but is relevant enough to mention here: WXSIMATE can now read data from the program Cumulus, by Sandaysoft, in addition to the previous set of software packages with which it is compatible: Davis WeatherLink, Brian Hamilton's Weather Display, Ambient's Virtual Weather Station, and Quimisur (a Spanish company). At this time, the use of Cumulus is limited in three ways: (1) the "compare to actuals" tool in wret.exe is not functional for Cumulus, (2) the associated "learning" routine are not functional in wret.exe, and (3) soil temperature and moisture data are not read. (2) and (3) are features of WXSIM's professional mode and therefore do not affect use in standard mode. So, standard mode is very nearly full-featured for use with Cumulus. I may add some or all of these features in the future, but do not have any current goals for when this might get done.
• Reports from high-latitude users (i.e. Finland) indicated that WXSIM was reducing snow depth too rapidly in sub-freezing weather. Investigation, backed by research such as in this study: Differences in Compaction Behavior of Three Climate Classes of Snow (PDF)
  showed that the main problem was not melting or sublimation, but overly rapid compaction of the snow under its own weight. Changes were made to generally reduce this rate, and also make it temperature dependent (slower compaction at lower temperatures).
• A change was made which should fix the occasionally reported 'forgetting' of the 'RAOB' and 'READY or GFS' check box settings on the data import form (assuming the problem found was the only cause). When unrecognized and not corrected, this problem led to messages about no model data being found, and the resulting forecasts were generally poor.
• A variety of messages which previously interrupted program execution, awaiting a user response, have now been handed over to a new, small program (included in the WXSIM upgrade and demonstration packages) dedicated to their display. This allows WXSIM to continue and complete the forecast and yet assures that the users knows about the problem(s), which are usually about missing data. The messages are also displayed in a text file called msglog.txt.
• A program called trimlog.exe has been included in the package (but not given a Desktop icon at this point). This is a tool for users of the Weather Display program who may find import into WXSIMATE to be slow. Trimlog can run on its own scheduler to produce much smaller versions of the Weather Display log files, allowing import time to be cut by a factor of almost 10.
  

Version 12.8.11 (July 16, 2012) had the following changes relative to Version 12.8.10 (described below):

• The 'suspicious initial wind data' message in auto run now appears only under more extreme conditions, 32 mile per hour discrepancy as opposed to 16, though values over 16 are still reduced to 16 before use.
• A limit was placed on the lapse rate between levels 3 (approximately 700 mb, for most sites) and 4 (500 mb), to keep it a bit short of the dry adiabatic lapse rate. The value used is slightly dependent on surface elevation and is based on considerable research of historical RAOB soundings. Also, a bug in a beta release of this version has been corrected in the final one here.
• For sites with actual (not adjusted to sea level) surface pressures below 970 mb, the Total Totals Index (TT) has been modified by mixing it with an alternate definition (called HLTT or High Level Total Totals) in which 700 mb replaced the original 850 mb in the formula. The K, KO, and Showalter indices are modified similarly but indirectly, based on the change between TTI and HLTT. This indirect method was used because, while I did have some data correlating TT, HLTT, and convective threat, I did not have separate data correlating 700 mb version of the other indices with such threats. The new indices are equal to the old ones with surface pressure above 970 mb, and gradually transition to the high level versions as a surface pressure of 850 mb is reached. This change was made because some moderate to high elevation sites were getting overly aggressive convective indices.
• The 'reduce superadiabatic' routine was modified to have less effect for surface pressures below 970 mb (that is for higher elevation sites). When the previous version was used for these sites, high temperatures became somewhat too warm and the air too unstable. The effect now transitions gradually from its original value for surface pressures above 970 mb, to half that around 945 mb, to very small but non-zero values at much lower pressures.
• The READY/GFS bias correction (top of tab 4 under Preferences/Settings) has been modified so that, while the initial temperature correction is the same as before (with a given setting), the trend part is reduced to 0.67 of its original value. This was done to correct a tendency, in long range (over a week) forecasts for too-large of a drift to occur. For instance, while an input positive value of, say 0.5, would produce only a modest temperature for the first few days, later in the forecast the change would become too large. The change shouldproduce more consistent day-to-day temperatures (aside from a multitude of other effects, of course).
• A bug, which could produce a 'file already open' error after a message about GFS data being for the wrong site, has been fixed (the message can still appear, but hopefully not the error that could follow it).
• Many new avenues of communication have been opened between WXSIM and the optional multi-site controller program, WXSIMPRO. One example is a short file called wxsimopen.txt, which should consist of the number 1 if WXSIM is open, and 0 if it is not. Also, WXSIMPRO can now optionally have WXSIM default to climatological normal sea surface temperatures instead of retaining values from an earlier run. Messages related to this in both programs have had wording changes. Most of these changes are not visible when not using WXSIMPRO.
• A change was made in the Retirevel program (wret.exe) to enable the Auto Select routine to successfully bridge across from one month to another (previously, for VWS data, forecasts spanning months were rejected from the analysis). Months were already bridged successfully for Weather Display and WeatherLink data, at least.
  

Version 12.8.10 (December 19, 2011) had the following changes relative to Version 12.8.9 (described below):

• A bug, which could occasionally cause an 'invalid property value' error, has been fixed. This error would occur if WXSIMATE somehow (perhaps through some kind of interruption) failed to finish writing the localcal.txt file. It is still possible WXSIMATE may do this, but there is only a trivial loss of data which would have no perceptible effect on WXSIM's forecast. Now WXSIM should be able to handle this situation without error or interruption.

Version 12.8.9 (November 23, 2011) had the following changes relative to Version 12.8.8 (described below):

• The wret.exe module's 'Auto Select' routine for determining learned bias correction factors has been improved in two ways. First, a careful study of the effect of corrections motivated a change in how the 'tendency towards normal' factor is determined. These factors should now be slightly more conservative, and accurate, than before. Second, the heavier weighting of more recent data is now an option (the 'Weight recent more' box must be checked for this), with the default being to weight all data equally. The equal weighting is a bit 'safer', but unseasonal spells may still call for the heavier recent weighting.
• A few places in wret.exe allowed values to be printed in lastret.txt with enough digits to run columns together (an earlier attempt to correct this still left loopholes where the figures 100.0 and 10.0 could appear). This has been corrected.
• Minor changes were made to the help file, such as noting that the NGM model is no longer in production (as of 2009).
  

Version 12.8.8 (July 19, 2011, and August 12 for the wret.exe module), and has the following changes relative to Version 12.8.7 (described below):

• The default value (and only value in standard mode) for the minimum level 1-3 sky cover necessary to allow external-model-based precipitation was changed from the previous 40% to 20%.
• The minimum 12-hour precipitation probabilities for "possible" and "likely" thunder have been changed from 15% and 25%, to 10% and 20%, respectively, thus making appearance of thunder slightly more likely in the plain text output. This would be most noticeable for precipation probabilities between 10 and 15%, where the former "Precipitation showery or intermittent" wording will change to "Scattered thundershowers possible".
• In wret.exe, the number of decimal places for precipitation rate and total precipitation has been reduced in the case of large numbers (i.e. 100 mm or more) which would run into other columns if the original decimal places were retained.
• In wret.exe, horizontal visibility's units are now dependent on the temperature unit choice instead of the previous thickness unit choice. When Fahrenheit is in use, visibility units are now miles; with Celsius, they are in kilometers. Also, if the visibility (in either unit system) has a value less than 10, one decimal place will be displayed. (Previously it was a whole number in all cases).
• In wret.exe, you may now check up to 15 temperature items and 15 'other data' items. As before, only the first 5 of each will be displayed on the screen, but the entire set will appear in lastret.txt. Also, some minor formatting changes were made in lastret.txt, to remove some of the excess spaces when fewer than the maximum number of items are selected.
• In wret.exe, two new temperature values were added: the maximum and minimum temperatures from which daily max and min values are obtained. Around the time of the maximum, the difference between the new max value and the most likely 1.5 meter temperature (the main forecast value) is an indication of the amplitude of the largest short-term fluctuations likely (though the new min value at the time of the max is less meaningful, and often a bit warmer than the lowest temperature due to short-term fluctuations). Around the time of the daily minimum, the difference between the new min value and the 'main' temperature indicates fluctuation amplitude, with the max value a bit less meaningful. In short, these are simply values from which daily max and min temperatures can be extracted.
• In both WXSIM and wret.exe, the upper end of the convective sensitivity adjustment has been extended to +2 instead of the previous +1.
• In both WXSIM and wret.exe, minor cosmetic changes and changes to the help file were made.
• In both WXSIM and wret.exe, summaries at the end of the text display now show 24-hour max and min temperatures to the nearest tenth of a degree, instead of the previous whole degree. This should not be understood as a claim of higher accuracy, but the decimal places might be interesting for comparisons or identifying trends in the program's behavior.
• In wret.exe, after the message that too many temperatures (or 'other data') options are checked, the program will automatixcally uncheck the last item you check, thus preventing errors that would occur if you proceeded without heeding the message.
• This item was actually present in 12.8.7, but I forgot to list it below: A check box on the Auto Run form allows you to have the date listed along with the day of the week in the plain text output.
• Numerous improvements and additions were made to the agricultural module. Soil moisture is now reported in soil moisture tension as well as percent by volume, with these being functions of each other as well as of soil type. Both soil moisture and temperature can now be imported (via WXSIMATE Version 5.0) from either WeatherLink (for up to 5 depths) or Weather Display (for one depth, and possibly more in some later version), and this can work in auto mode as well as manually. Irrigation can now be planned on the Interrupt Planner, and this, along with soil moisture tension, can be plotted in wret.exe as well as output in WXSIM itself.
• Several small cosmetic, organizational, and wording changes were made in wret.exe.
• An occasionally encountered bug producing a "division by zero " error has been corrected. This problem most likely occurred only if local calibration data was being used, and required a rather special set of circumstances, so that it was sporadic in nature.
• In addition to the changes listed in (12), the algorithm for the default soil moisture (as a function of location, season, and recent precipitation) has been improved considerably.
• In wret.exe, a bug - which caused text and lastret.txt display of all soil moistures to be that at depth 1 - has been corrected.
• Bugs which could cause division by zero or invalid property value problems were fixed. These were associated with interpretation of local station calibration data in localcal.txt.
• Output format of certain variables to lastret.exe in wret.exe, such as severe weather indices, was changed so that values of -10 or more negative are rounded off to whole numbers, so that columns of data won't run together.
  

Version 12.8.7 (June 10, 2011) had the following change relative to Version 12.8.6 (described below):

• The results of a recent careful study on thunderstorm activity as a function of various stability parameters (especially the K and Total Totals indices) using many U.S. surface and upper air sites' historical data (spanning up to 25 years) - combined with information from two large studies in Europe (Germany and the Netherlands) was used to substantially improve WXSIM's convective bulletins. A very thorough description of this improved algorithm is now included in this manual.
• Slight changes were made in the wording of convective bulletins. Also, the following plain text convective output now consists of:
  " Precipitation showery or intermittent."
  " Scattered showers possible."
  " Scattered thundershowers possible."
  " Scattered thunderstorms likely."
  " Scattered thunderstorms likely, some possibly severe."
  " Thunderstorms very likely, some possibly severe."
  " Thunderstorms very likely, some severe."
  " Severe thunderstorms likely, with possible tornados."

These were removed:
" Thunderstorms likely, some severe."
" High risk of severe thunderstorms and possible tornados."

• The plain text convective bulletins now take into account thresholds of 12 hour probability of precipitation. This helps screen out occasional contradictory information (such as thunderstorms "likely" when rain chances are below 20%), though it may cause some inconsistency with the scrolling convective bulletins, most likely in that a few convective bulletins may be more aggressive than the final plain text output. If this is found to occur frequently, a small downward adjustment in the convective sensitivity may be in order, since the final plain text forecast incorporates a bit more information than do the bulletins.
• The automatic level 2 cloud cover minimum of 60% during precipitation has been reduced to 45%. This could increase temperatures very slightly on afternoons with light shower activity, but a recommended slight change in the GFS temperature and cloud cover bias (see #6, below) may just about exactly cancel this out on average.
• A major review and readjustment of the routines for finding heights and thicknesses of the various pressure levels was conducted. The changes made include updating the virtual temperature calculation to an official published equation (previously it was a fairly good, empirical one I had developed), including level 3 and 4 relative humidity values (values up through level 2 were already incorporated, but above that default values had been used), establishing new ways of averaging the limited temperature data to best characterize layer average values, and (importantly) removing an altitude-based correction to the acceleration due to gravity, so it is now a constant 9.80665 m/s/s, as appears to be standard for the geopotential (as opposed to geometric) heights that are standard in imported model data.
• A thorough review of GFS temperature verification results, from this site:
• STATS VSDB
• strongly suggests that a cold bias which existed a few years ago has been largely corrected. For this reason, the default value for the upper level temperature bias correction has been changed from 0.5 to 0 (professional version users will need to change this manually, but the change will be automatic for standard version users). Also, verification results from about 1200 forecasts over the last year here in Atlanta suggest that GFS biases in cloud cover and precipitation (a previous year of data had suggested the model was too cloudy and wet) have also largely disappeared, so the bias correction setting for cloud cover, precipitation intensity, and precipitation intensity skew have been changed from the previous -3, 90, and 2, to -1, 95, and 1, respectively. This will generally increase cloud cover by about 4% and precipitation by about 5%. Professional mode users should consider their own accumulated experience as local effects can be important here.
• More thorough data on 700 mb relative humidity in WXSIM was made accessible to wret.exe.
• The forest effect on snow cover was increased somewhat.
• A bug in wret.exe that caused values of UV index to be too high was corrected.
• In light of new data, the UV index algorithms in WXSIM was revised generally downward by about 7 or 8 percent, and the elevation effect part of this was improved also.
• The UV index algorithm used for display on the main Data Entry form of WXSIM was found not to be consistent with the one used in the output. These two instances of UV index now share a common algorithm.
• An option was added in wret.exe to include a numerical convective parameter in the lastret.txt file (created when 'View Text' is selected).
• The default dew point depressions, as functions of layer cloud cover, were changed for levels 2 through 5. In particular, cloud cover of less than 10% now gives dew point depressions tending towards 14, 18, 16, and 15 degrees Celsius for levels 2 through 5 respectively. This was based on averages of all soundings from Athens, Georgia, for days with less than 10% average total cloud cover, over a 6 year period.
• A new setting was added to the Local Data Import form, allowing specification of a minimum sun altitude (default 10 degrees) for using estimated cloud and haze data from WXSIMATE. This is useful because low sun angles yield relatively unreliable solar-radiation-based cloud and haze estimates. The setting specifically refers to sun altitude 30 minutes before the forecast initialization time, because the default time span used in WXSIMATE (for collecting solar radiation data for this purpose) is the hour leading up to the forecast time.
• A new setting on tab 4 of the Preferences/Settings form allows specification of a threshold value for combined level 1 through 3 cloud cover (in percent), below which precipitation will not be forecast, even if present in FOUS data or on the Interrupt Planner. This is probably most useful in cases where the orographic downslope effect is in use; the reduced cloud cover in such cases may well be accompanied by an elimination of precipitation. The default value (and only value for standard mode) is now 40%. If precipitation was previously supposed to be forecast at a certain time, a small increase in cloud cover may be observed in the forecast as a vestige of what would otherwise have been precipitation.
• The 'Reduce superadiabatic' feature was modified by weakening the effect slightly, so that even with it active, the near-surface temperature lapse rate will be allowed to exceed dry adiabatic by a slight amount - and by slightly more than before.
• The 'enhanced maritime effect' was expanded to include a reduction in the cooling effect of precipitation, considering the fact that the nearby or surrounding sea is not made any more wet by rain falling on it, and thus removing a component of evaporative cooling that would exist for an inland site.
• A protection was added against a very rarely encountered report of freezing rain with temperatures well above freezing.
  

Version 12.8.6 (March 11, 2011) had the following change relative to Version 12.8.5 (described below):

• A protection in wret.exe, against trying 'comparison to actuals' or 'auto select' when more than 5 items are checked in either the 'temperature and thicknesses' or the 'other data' section, has been changed to allow up to 10 items, which is the maximum anyway (5 of which would show only in lastret.exe). Previously, if such a run was attempted with more than 5 items checked, the program simply did nothing. Now it will complete the requested task.
• A safeguard was added in wret.exe against a 'division by zero' error during an 'auto select' run, in the rare case that the average departures from normal of the warmer and colder halves of the data points are identical. Now such an occurrence will simply generate a slope of zero for the temperature error as a function of departure from normal.
• A new feature was added to Preferences/Settings, allowing the user to specify a description the density of forest (especially evergreen) in the surrounding area, for modification of the effect of snow cover. Some consideration had been given to this already, in the form of a ground cover parameter included in the customization. However, this appears not to have been sufficient for describing situations such as dense fir forest in high northern latitudes, where the dark trees considerably mitigate the cooling effect of the otherwise high albedo (reflectance) snow cover. Any setting entered by the user is saved on exit.
• A small problem with snow:water ratio as used during the calibration run was corrected (it had defaulted to a value of 2 in most cases). This change will have only a very small effect on forecasts.
  

Version 12.8.5 (February 19, 2011) had the following change relative to Version 12.8.4 (described below):

• A sophisticated and carefully researched new algorithm replaces the former one for estimating wind gusts. The new routine takes into account the user's choice of definition of gusts (i.e. higest wind in a 10 minute period, versus highest in a 60 minute period) and allows adjustment of gust factors by the user, who can also specify the lowest speed wind gust to be reported in the plain text output.
• A caption, just under the site information on the Data Entry form, now displays whether professional mode is OFF or ON, and whether auto run is OFF or ON.
• A bug, which caused small errors in the drawing of the upwind direction (thick arrow and dotted curve) on the advection sites map, has been corrected. This would mainly have been noticed in manual mode (or in auto run if you were watching very closely) and different flow curvatures were being tried. It did not affect auto run forecasts, but could have influenced user decisions when experimenting with flow curvature choices manually.
• A bug, which could cause the program to get into an endless loop of saying "Calibration Run" if the cor.txt file was corrupt, has been fixed. Now, such corrupt files (how it got corrupted is yet to be determined) will be identified as such, the user will be notified by a message box, and the run will be allowed to complete, using default correction factors of 0, 1, 0, and 0. At the same time, a more centralized error trapping method was instituted, to hopefully make identifying any future run time errors easier.
• A protection was added to guard against unrealistic wind values that could result if either the localcal.txt or localdat.txt files were somehow corrupted during or after an import of local station data using WXSIMATE. This protection was added in response to the only reported case of the problem, which produced a brief period of abnormally strong winds.
• A bug, which could cause an 'invalid property value' error if the Stop AM Rain refinement was chosen, has been fixed. The error probably appeared mainly in the winter season, and this is a summer season feature, which is probably why the bug took so long to show up. Note that this feature boots up with default times, except in auto run, where the settings are remembered from the last run.
• Wind chill wording was changed to include both the lowest and highest values of each 12 hour forecast period (when colder than a threshold of -3 C), with the term "ranging from … to".
• The snow remembering routine was changed to avoid errors which could occur with certain Windows regional settings which use decimal separators other than periods. If the old format is encountered, a message will alert the user to this fact, with instructions to temporarily disable the routine to let a new forecast run, at which point it can be re-enabled.
• Wind gusts over 1 and 10 minute and 1 and 6 hour periods were added to the display options in the retrieval module (wret.exe).
• A bug (which may have existed for many years) involving wind chill in wret.exe was corrected. This bug had caused erroneous graphical and text display of wind chill values when wind speed units were other than miles per hour.
• Now up to 10 items from the temperature-related options, and also 10 from the 'other' data options, can be chosen in wret.exe. Only 5 from each group can be displayed as text or plots, but the others will appear in the lastret.txt file. If you do choose more than 5, the program will decide which 5 to display, as currently there is no mechanism for making this specification.
• Choices for data to display in wret.exe have been rearranged into more logical grouping.
• Protection in the form of a message box (manual mode only) and reasonable default values was added for extreme wind speeds from potential misinterpretation of METAR or other ingested wind data.
• Megajoules per square meter were added (to Watt x hours per square meter and Langleys) as an option (under Preferences/Solar Energy Units) for output total daily solar radiation. A similar addition was made to wret.exe (the retrieval module).
• Precipitation and total solar radiation units were added to the hard copy printouts available for Plots in wret.exe.
  

Version 12.8.4 (January 11, 2011) had the following changes relative to Version 12.8.3 (described below):

• A bug, discovered in the 'snow remembering' routine just introduced, has been fixed.
• The formatting of the snow depth box on the snow/ice entry form has been changed to round off to the nearest hundredth (this change prompted by the appearance of decimal values in this form in some cases after use of the 'snow remembering' routine).
  

Version 12.8.3 (January 11, 2011) had the following changes relative to Version 12.8.2 (described below):

• Further testing of item #7 for 12.8.2, below showed errors in the normal diurnal range of some sites. This turned out to be due to mathematical errors out in about the 12th digit, perhaps due to to the precision and type of the variables involved. Normally such a problem would be trivial, but a condition (whether or not the variable's value was exactly zero) that had been set made the effect much larger. This has been corrected with a protection against the resulting extreme values. Now both old customizations and future ones should function properly.

Version 12.8.2 (January 10, 2011) had the following changes relative to Version 12.8.1 (described below):

• The tolerance for triggering a message about sea surface temperature being out of range was increased from 2 Celsius degrees (3.6 Fahrenheit degrees) to 3 C (5.4 F).
• A typo ("Relativelymild") in the plain text output was corrected. Also, freezing rain wording for metric units had "above ground" added, for consistency with imperial units.
• Wind chill during the daytime periods in the plain text forecast was changed to reflect the *warmest* value during the day, with wording such as "Wind chill colder than …".
• The (somewhat rarely used) READY data turns out to have changed format slightly at some point, which led to WXSIM omitting precipitation while parsing. This has been corrected, and simultaneously, arrays have been expanded to handle the 3-hourly READY data out to 192 (instead of the previous 180) hours.
• A bug (starting with Version 12.8.1), which kept wret.exe from recognizing old correction factors in forecasts, has been corrected.
• Start and ending times for the forecast run itself were added to the latest.txt (and archived versions) file.
• A parameter has been added for future customizations that will permit slightly better matching of some sites' climatological diurnal temperature ranges (thus affecting displayed normal max and min temperatures).
• A bug (discovered as I was testing (7), above), which allowed inaccuracies of perhaps a degree or two in the displayed normal max and min temperatures (by not fully determining the normal diurnal range as intended) has been corrected. This has virtually no effect on forecasts and had only a very slight effect on the quality of some customizations. Earlier customizations affected by this will now show more accurate climatological temperature data.
• Top layer (the top one centimeter) soil temperatures are now initialized more accurately due to improved interpolation and extrapolation algorithms.
• A new parameter, called 'Base insulating effect', has been added to the soil data form. The need for this arose as I did additional testing on both summer and winter soil temperatures in various scenarios, using data from the Soil Climate Analysis System (SCAN). This appears needed to represent thermal effects (mostly simple insulation, I believe) apparently due to grass turf ground cover. It should probably be set to zero for truly bare ground, but otherwise, values around 2 seem about right for a wide range of conditions.
• A option to 'Initialze with previously forecast snow cover' (on the first 'tab' of the Preferences/Settings form) has been added. This allows WXSIM to start a new forecast using the snow cover from the last forecast run, specific to the date and time of the new forecast. You can still override this by entering the new snow cover directly, but this feature will be very useful if you must be away from the computer during a series of forecasts where snow is accumulating and/or melting. In this case, the snow/ice cover refinement does not need to be active (hightlighted red), though is may be.
  

 

Version 12.8.1 (December 30, 2010) had the following changes relative to Version 12.8 (described below):

• The interface for many of the settings was considerably rearranged, by creating a new form, under a new item called 'Settings' (under Preferences on the main menu bar). On this form is a combination of the former text width form, the minimum UV and precip form, the fog and frost options form, and the model bias form. Some items from the Interrupt Planner were also duplicated for easy access, especially for users doing mainly auto runs.
• Sliders were added (to the form in (1), above - professional mode only) to control the strength of the 'allow decoupling' and 'additional maritime effect'.
• Site and date specific temperature variation data has been added to this new form.
• The ability to specify upslope, downslope, and lake-effect directions for wind has been added. These features, available only in professional mode, can alter cloud cover and precipitation amounts derived from imported model data in order to model effects on a scale smaller than that of the model (mainly GFS) data. Proper use of this feature will require study on the part of the user over time, and controls are provided to allow the user to tweak these settings based on accumulated experience.
• Optional wind and temperature descriptors have been added for the plain text output. The wind part is fairly straightforward ("breezy" for >12 mph, "windy" for >17, and "very windy" for >25). The temperature part is very sophisticated, taking into account not only actual temperature, but also wind chill values and number of standard deviations from normal specific to the site and date.
• Wording rules for precipitation in the plain text output have been changed so that probablilities or amounts will not be mentioned unless there is a specific reference to precipitation or at least a chance of convection in the forecast.
• Changes were made to wxsim.exe which now allow use of newly created (using wret.exe) bias correction factors without having to restart WXSIM.
• Changes were made in wret.exe so that, if the "learning" option is turned off in WXSIM, the effective correction factors for those forecasts will be considered to be the default values.
• Protections (in the form of message boxes) were added to wret.exe so that users are much less likely to take an incorrect sequence of actions which might have led to an error.
• A bug, which could occasionally carry over precipitation from the end of one forecast to the first line of text of the next, has been corrected.
• A possible 'Invalid property value' error when using imported precipitation data has been averted.
• An oversight which on rare occasions could allow METAR reports of runway condition to be misread as temperature and dew point (possibly leading to 'dew point cannot exceed temperature' message) has been fixed.
• Another METAR import bug which could also very rarely lead to a dew point being read as a barometric pressure (hence triggering an 'unrealistc barometric pressure' message) has been fixed.

 

Version 12.8 (November 30, 2010) had the following changes relative to Version 12.7.5 (described below):

• A new suite of calculations of agricultural interest, such as soil temperature and moisture, and evapotranspiration, was implemented, and is available in professional mode. A new menu item in the main program was added to accommodate user defined choices of output. These new output variables (23 in all) can also be viewed as plots or text in the retrieval module (wret.exe). Further refinements and features can be expected in upcoming versions.
• A message box which was new to Version 12.7.5, but which I forgot to document below, was causing problems for some users. This message was intended to detect if another version of WXSIM was open, and alert the user to that fact. In some cases, the message appeared inappropriately and interfered with auto runs. This "new" feature has now been removed, as it may have caused more problems than it avoided.
• Two problems with temperature forecasts for island, coastal, or near coastal areas were addressed (a typical, but not unique problem region being New Zealand). One is that of too-high maximum temperature forecasts, mainly in spring. The other is that of too-warm minimum temperature forecasts on calm clear nights, just about any time of year, but perhaps most prominently in winter. The first problem was identified as an inappropriate lack of marine influence when winds were from the "inland" direction, especially when water is not too far in the direction (as on an island). The solution is an optional sea-breeze-like influence (but without modification of wind), which can operate either with or without the existing sea breeze routine (the effects are roughly additive). The other problem was addressed by increasing the effects of the existing 'allow decoupling' routine (check box on the Interrupt Planner), using an additional component to the routine which specifically increases diurnal temperature range. Both of these routines are influences by a new input on the form reached by selecting 'Min UV and Precip, Sea Breeze, and Advection item under parameters. This new item lets you define a distance to the far side of an island or peninsula, up to 100 miles (161 km) distant.
• A significant problem with the "learning" routine ('auto select') in wret.exe was discovered and corrected. This was actually making forecasts *worse* for some users. It manifested in the slope of the error versus departure from normal line. The earlier "correction" was exactly backwards, and either made too-extreme forecasts more extreme, or too-moderate forecasts even more moderate (in terms of departure from normal seasonal mean temperature). One indication of the problem was frequent appearance of a message that the slope correction was 'out of range' and would be 'limited' (which is a good thing, as the limitation kept the problem from getting too far out of hand.
• A number of cosmetic and display changes were made in wret.exe, including the addition of mean temperature of a forecast period on the graph showing temperature errors versus day of forecast. Also, the "proposed" line on the graph of temperature error versus departure from normal now has a more clear meaning. It now shows the correction that will be made in practice if the proposed values are accepted.
• The text width scroll bars in both wxsim.exe and wret.exe were given greater ranges, in order to accommodate different font sizes and resolutions that may be available with newer versions of Windows.
• On the Text Width, Heat Index, and Frost Options form (under Parameters), users can specify a choice of conditions under which to display frost as an output in the plain text output. This includes an option to mention frost only if it is "climatologically significant", meaning unusual enough for the season to be "newsworthy". This decision is guided by WXSIM's own internal estimate of the climatological probability of ground frost occurring on the current date. NOTE - This feature has already been present since about Version 12.7.2, but I forgot to describe it sufficiently before. ANOTHER NOTE - I have become aware that, in many countries "frost" refers speficically to the occurrence of freezing temperatures. This is NOT the meaning in WXSIM, where it instead refers to a form of condensation (more properly, "deposition") of water ice onto surfaces like grass or cars. "Heavy" frost, here, means a lot of the white stuff, not necessarily especially low temperatures.
  

Version 12.7.5 (July 2, 2010) had the following changes relative to Version 12.7.4 (described below):

• Changes were made to the plain text output decision algorithm, mainly to prevent mention of precipitation chances below 20 percent when the 'Omit trace amounts or very slight chances of precipitation' box is checked. This is actually a second attempt at the fix in 12.7.3, which still had a loophole and was not fully successful.
• A bug was discovered in the sea breeze routine, in which it wrongly used north as a default water direction when reactivated during auto run. This has been fixed, as was a closely related problem involving the mountain/valley breeze routine, where is had been 'forgetting' the diurnal breeze amplitude.
• The Diurnal Breeze form (containing both the sea breeze and mountain/valley breeze controls) now had a 'Reset Defaults' button, which if clicked populates the form with the originally customized data, including current seasonal sea surface temperature (adjusted to site level, as always, with a lapse rate of about 3.5 degrees F per 1000 feet or 6.5 degrees C per kilometer).
• There is now a message box which warns the user if, in auto run, the retrieved (at boot up) water temperature is different from the default climatological value by more than 4.5 degrees F (2.5 degrees C). This si intended to prevent the problem of unseasonal default water temperatures being used in the forecast when users do not reset the value reasonably often.
• A very small bug, which could make temperature forecasts on subsequent runs using identical data different by perhaps a couple tenths of a degree, has been fixed. It was due to an inconsistency in how the 'air mass temperature' was determined the first time through, versus on subsequent runs.
  

Version 12.7.4 (July 1, 2010) had the following change relative to Version 12.7.3 (described below):

• Change #3 under Version 12.7.2 (below) was discovered to cause an occasional error #5 (invalid procedure call or argument). This has been corrected, while preserving the new parsing ability introduced in Version 12.7.2.
  

Version 12.7.3 (July 1, 2010) had the following change relative to Version 12.7.2 (described below):

• A change in the plain text output algorithm, introduced in 12.7.2, caused a change in the output in the case of using the 'Omit trace amounts or very slight chances of precipitation' box on the 'Minimum UV Index and Precipitation for Display, etc.' box. It should now behave as before.
  

Version 12.7.2 was completed on June 29, 2010 and has the following changes relative to Version 12.7.1 (described below):

• An isolated instance of failure to recognize commas as potential decimal separators (in certain Windows regional settings) was corrected.
• An option (mainly for Canadian users) to use humidex instead of heat index was added, and can be accessed under Preferences on the same form as text width. Humidex was also added to wret.exe's optional outputs.
• METAR barometric pressures failing to use standard prefixes ("A", "SLP", or "Q") are now read anyway. Also a default pressure of 29.92 inches of mercury (1013.2 millibars or hectopascals) is now assumed at the beginning of METAR import in case no pressure reading is found.
• WXSIM now detects other open copies in the same folder, or instances of failure to close the program properly, and alerts the user to this with the choice to proceed or quit (and perhaps either use or close any other open copies).
• WXSIM now optionally includes frost descriptions in the nighttime forecast periods.
• The frost decision routine was modified using additional data, including information on the difference between 'grass' temperature (within 10 cm of the surface) and 1.5 meter "shelter temperature", from hisklim7.pdf
• The plain text output (saved as plaintext.txt and also incorporated in some other products) now includes (optionally, if Convective Bulletins are enabled under Preferences) mention of showers, thunder, or severe weather if WXSIM considers the probability sufficiently high, even if imported model data doesn't suggest measurable precipitation.
• A new option, activated by checking the new 'Allow decoupling' box on the Interrupt Planner form, permits WXSIM to decrease both maritime temperature-moderating influence and the strength of warm air advection when the strength of (mainly nocturnal) temperature inversions exceeds a certain, rather weak, threshold value. This effect increases with the strength of the inversion and is therefore strongest on clear, calm nights. It is most significant in coastal and near-coastal areas and its main effect is to lower nighttime low temperature forecasts. This change was motivated by reports of too-warm overnight lows, mainly in coastal areas, under clear conditions with light winds.
• Made minor cosmetic and help files changes.
  

Version 12.7.1 (February 20, 2010) had the following changes relative to Version 12.7 (described below):

• Provided error handling in case a printer is not declared. Now, a message will appear explaining the need to do so, along with instructions for how to do so in control Panel.
• Fixed a bug which could cause errors in the station precipitation amount in Comparison's in wret.exe for users of Weather Display
• Made minor cosmetic changes.
  

Version 12.7 (February 15, 2010) had the following changes relative to Version 12.6.3 (described below):

• A 'subscript out of range' error that could have occurred when importing GFS data that is initialized after the forecast (which can happen only if you are running forecasts after the fact) has been averted.
• Another 'subscript out of range' error that could have occurred when importing GFS advection data for a different site has been averted. A message box will now appear alerting the user to import fresh GFS advection data relevant to the current site.
• The optional GFS temperature and dew point plots on the Output form's graph now have correct colors for the current background color (an earlier coding problem had led to low-contrast displays).
• Thunder and severe convection outputs (the same ones displayable in wret.exe) are now written to the main (not 'daily') .csv output file. Column headings help describe these roughly 0-5 scales.
• An option has been added to the Auto Run form to execute a user-defined DOS batch file after auto runs or after the user clicks 'Repeat' after a manual run. Possible uses might include converting a .bmp file to a more compact format (like .png) using another program, uploading files to the internet, or a combination of such actions. A sample batch file, called latestbmppng.bat, is provided in the demo package to instruct IrfanView Version 3.2 (see www.irfanview.com if you are interested in obtaining this program) to convert the optionally produced graphic latest.bmp to latest.png in the c:\wxsim folder.
• An option has been added (to the Minimum UV Index and Precip form) to adjust the effectiveness of diurnal breezes (sea breeze or mountain-valley breeze). This affects the diurnal wind vector component and also (in the case of sea breeze) the direct effect on temperature. It is strongly recommended that users research their forecast bias histories before considering any such alterations.
• Another option added to the above form adjusts the effectiveness of cold or warm advection. It is strongly recommended that users research their forecast bias histories before considering any such alterations. The only locations I know of at present that seem to warrantthis intervention are in southern Greece.
• Various cosmetic changes were made, including adding program-specific icons to the forms in both wxsim.exe and wret.exe, and changing the background color of the help forms in both programs from yellow to a less harsh tannish-orange.
• Changes were made to the vertical lines on both the regular and comparison plots in wret.exe. On the regular plots, the bright blue vertical lines (which did not consistently mark days) were made a darker blue, and with other dark blue lines form an unobtrusive finer scale (easily interpreted only when showing 2,3,4,6, or 8 days) than the gray lines marking midnights. The comparison plots' blue lines were removed and, instead, the dark gray lines now show midnights while the light gray lines show every six hours.
• The fog sensitivity wording was changed to put the default value of 45 (instead of the previous 50) in the middle of the 'normal' range. Also, the description is now highlighted in red if it is outside the range of 'low-normal' to 'high-normal'. Similar behavior was also built in to the new diurnal breeze and advection adjustments, (6) and (7), above.
  

Version 12.6.3 (November 22, 2009) had the following changes relative to Version 12.6.2 (described below):

• A change was made to avoid an 'input past end of file' error (#62) when WXSIM tries to access GFS data for advection, and it's not present. This error generally occurred if the 'GFS for advection' box in WXSIMATE was not checked (it generally should be checked, as this is a valuable source of data for most users). Now the program should silently close the file with missing data without producing an error.
• A cosmetic error introduced accidentally in 12.6.2 (the 2 PM check box on the auto run form had been shifted in front of the 1 PM check box, rendering the latter invisible) has been fixed.
  

Version 12.6.2 (November 21, 2009) had the following changes relative to Version 12.6.1 (described below):

• The ‘~Monotone’ check box on the advection form was replaced by a ‘Mono’ scroll bar which allows mixing of the monotone and not monotone fits in various ratios, from 0% monotone to 100% monotone (in increments of 10%). The default value is 50%, which is generally a good compromise between getting the closest fit to the data points and avoiding unrealistic extrapolations. This setting is not saved. The 50% default is also used in auto run, unless ‘Enforce monotone’ is checked on the auto run form, or there is a strong inversion. In these cases, the fit will be 100% monotone, meaning the advection profiles for temperature and dew point will not have any slope reversals.
• The GFS advection data across longitude 180 degrees (see #1 below) is now active on Chris McMahon’s site, and the feature is now fully operational.
  

Version 12.6.1 (November 14, 2009) had the following changes relative to Version 12.6 (described below):

• Support was added for advection across longitude 180 degrees (such as in New Zealand with winds from the east), in anticipation of expanded coverage in the GFS files for advection produced by Chris McMahon.
• Colors were changed for the temperature and dew point displayed by the 'Show GFS' button on the Output form. Previously (by mistake) they were not matched properly with the blue or gray backgrounds of the graph. They now will be displayed with the same colors as WXSIM's forecast values, but with thicker lines.
• A scale was added for the wind speed arrows on the advection data maps.
• Minor informational and cosmetic changes were made to the Auto Run form.
  

Version 12.6 (September 19, 2009) had the following changes relative to Version 12.5.4 (described below):

• Support was added for a new set of GFS data kindly downloaded and culled by Chris McMahon. This is GFS data, but now for a 20 x 20 degree grid surrounding the home site, so that GFS may now be used for advection data, both initially and after wind shifts. This feature should be especially useful for users outside North America (since they do not have MOS for after wind shifts), but also for North American users more than 2 or 3 days into a forecast, when MOS runs out. It will also be helpful for users on islands or near coastlines, as data from ocean locations will be available (the extent depending on my original allotment of surface advection sites in the customization).
• GFS data can be used to fill out the main Data Entry form values, with most of it coming from the new data set, except for barometric pressure, which uses the previously existing set. This is not the best way to fill out this form, since local METAR, synoptic, or home station data would be more timely and accurate. However, for remote sites with no surface data available, this should initialize the program well enough for a good forecast in most cases.
• A time series of GFS temperature and dew point data is now extracted, and can be displayed by clicking the new 'Show GFS' button on the Output form. This makes an interesting, direct comparison with WXSIM's own forecast on the Output form's graph.
• Internal changes in the auto run routine were made, which may reduce or eliminate the possibility of certain errors (especially number 52, 'Bad file name or number'). This change avoids opening the FOUS and RAOB data display forms, which should keep things simpler for Windows as it tries to thread the actions properly.
• A warning was added to all the options under the Start menu to prevent users from starting a new forecast without clearing the Ouput form from a prior run. This eliminates one possible cause of Error #52 (see above).
• A new, very small form consisting of a progress bar and percentage figure (appearing in the lower left part of the screen, just above theWindows 'Start' button) has been added, to display the percentage of the forecast complete so far, as it runs.
• There is now an option to 'Minimize forms' on the Auto Run form. This causes almost all forms to be minimized during auto runs. The exceptions are the small progress bar form (see above), the file import progress bar form (which appears intermittently, and in this case is moved to the lower left part of the screen, just above the new progress bar form). And - in the case of 'Run Immediately' - the Data Entry form. In a scheduled auto run, Data Entry will start out minimized if the program just booted, and will otherwise remain minimized once it has been manually minimized. These changes should enable users to perform other tasks on the computer while WXSIM runs, with only minimal distraction.
• Choice of surface data source (METAR, SYNOP, or GFS) is now saved only after import of data for the home site, and no longer after advection data imports. The reason for this is the complexity of choices now that all these (plus MOS) are now supported.
• The retrieval program wret.exe now checks for completeness of the initialization file retini.txt to trap errors resulting from damage (which a few users have seen, though the cause is at present not known). If damage (usually missing lines) is detected, wret.exe displays an error message to that effect and then attempts to restore the file using a backup file, retinibak.txt, which in turn is created as a copy of retini.txt if the latter is not damaged. Therefore, just one successful load of the program is sufficient to establish the backup file. Meanwhile, a copy of any damaged retini.txt file is saved as retinibad.txt.
• A new check box, 'Close program after auto run', has been added to the Auto Run form. If checked, this will cause the program to shut down right after the run is finished. The intention here is to save users, who use System Scheduler (or similar) to open the program, the trouble of also using such an external program to close WXSIM.
• Changes were made to wret.txt to allow comparison of precipitation forecast to actual values, and also to include averages as well as maximum and minimum values in the analysis of this plus existing items. NOTE: In order to analyze precipitation for past forecasts, WeatherLink users will need to run Import Data in WXSIMATE for all past months for which analysis is desired. This is best done by manually entering a date (make sure the Scheduler is OFF) early in the *following* month so that a file will be created for the entire previous (desired) month. Start in the past and work forward one month at a time. After this, the latest two monthly files will be updated (including precipitation) every time Import Data is run, so no further corrective actions will be needed.
• A small cosmetic change was made to allow better readability of weather types in the saved bitmap plots in wret.exe.
• In wret.exe, the default directory for the WXSIMATE-derived VWS and WeatherLink data files is now forced to the current (boot-up) directory of wret.exe for using the Comparison feature. This was already almost the case, but there was a loophole that might have allowed the path name to change in some cases of analyzing forecasts in other directories. The forecasts may be located wherever you like, but wxsim.exe, wret.exe, and wxsimate.exe must all be located in the same folder (usually c:\wxsim).
• Capacity for number of combined forecasts in 'Compare to Actuals' in wret.exe has been increased from 999 to 9999.
• A bug that could allow a 'File already open' error in wret.exe - when changing weather station software types and/or directories in wret.exe for Compare to Actuals - has been fixed.
• Changes were made in wret.exe to allow proper display and use of certain items which may have been affected by regional and language setting in Windows which use commas as a decimal separator. There now should be no problems in the program related to this.
• A change was made in WXSIM to hopefully preclude the possibility of a #Nul# value appearing for the diurnal range multiplier in the .wxf files.
• A change was made to allow a tolerance of 1 in either direction on 6 digit WXSIM registration codes, due to an apparent computational uncertainty in the encryption algorithm.
• Changes were made to avoid errors in case certain small, optional files (such as
  skiplog.txt) exist but are empty.
• Clarified language on ‘Auto Compare’ form in the Retrieval Module (wret.exe)
• A safeguard was added to prevent an error which could have occurred while using GFS advection data.
• Specified that the 'Retrieval Module (wret.exe) not found' error message really require that error code instead of assuming that this was the only such error that could occur.
  

 

Version 12.5.4 (July 8, 2009) had the following changes relative to Version 12.5.3 (described below):

• A bug which could occur after pressing 'Start Fresh' on the Output form has been fixed.
• Options were added to the Auto Run form, allowing omission of either the log files (log.txt and latestlog.txt) or the comma separated variable files (latest.csv and latestdaily.csv), or both, from the forecast run. These files are not essential to operation and their accessing (mainly in auto mode) may trigger sporadic 'Bad file name or number' errors (#52) on certain computers. The reason for this is not clear, but may be associated with having a number of other programs (perhaps especially Terminate Stay Resident, or "TSR" programs) active. If you encounter such errors, checking one or both of these new boxes may solve the problem.
• The wording of the command buttons has been altered slightly to be more descriptive, and the (new wording) 'Disable Auto Run But Keep Settings' button now allows any changes you made to settings to be saved, both within the current session and on exit, for later boot-ups.
• The 'Activate scheduler on next boot up' option now not only "sticks" (as it did before) upon leaving the Auto Run form, but also "stays stuck" when the Auto Run form is reactivated.
  

Version 12.5.3 (June 29, 2009) had the following changes relative to Version 12.5.2 (described below):

• A bug, which caused the program to stall if both the 'skip this screen' and 'start scheduler on next bootup' options were check, has been fixed.
  

Version 12.5.2 (June 25, 2009) had the following changes relative to Version 12.5.1 (described below):

• There is now a search option in the On-File Sites form, to locate a desired site by METAR, Name, State, or Country. This is mainly for the me (the author) so that I can more quickly find sites in my list of over 600. It may also be somewhat useful for the few users who have several sites.
• The data is now read using separate commands for month, day, and year, so that more date formats should now be supported. The two options for display are still MM/DD/YY and DD/MM/YY. (This change was actually implemented in 12.5.1, but I forgot to include it in the list below)
• There is now an option to archive forecast files in a directory other than that of the main program. You must first create the folder. Then, after running a WXSIM forecast, click Save. Then, on the form that appears, browse to and select the desired folder and save the forecast to it. This change will be remembered for future saved forecast, including automatically archived ones.
• There is now a check box on the splash screen (of the pretty sunset) allow you to skip that screen in the future. This was already possible in auto mode using the 'Start scheduler on next boot-up' option, but it can now be done without automatically starting the scheduler.
• A bug, which sometimes caused errors (mainly #52: 'Bad File Name or Number') in auto run (for those not booting WXSIM with a third program such as System Scheduler) has been fixed. Now, running WXSIM continuously through auto runs should be much more reliable than before.
  

Version 12.5.1 (March 23, 2009) had the following changes relative to Version 12.5 (described below):

• A bug, which allowed the time step (determined by output interval and iterations per interval) to influence the effect of the new temperature (slope) bias correction factor, has been fixed.
• Values of the new bias correction factors, if used, are now included in the log.txt or latestlog.txt files (right after urban heat island effect).
• A bug, which occasionally allowed data on a second line of a synoptic report to be mistaken for a station code, has been fixed.
  

Version 12.5 (March 21, 2009) had the following changes relative to Version 12.4.5 (described below):

• WXSIM can now read bias correction factors, determined from comparisons of archived forecasts with actual results (if you have a home weather station working with WXSIMATE). These are activated by checking the 'Use learned bias corrections' box on the form which appears when you click 'READY/GFS bias factors' on the Import form. Note: This feature is restricted to the professional mode, which all customers who ordered before July 23, 2008 already have. Upgrading from standard to professional mode costs $50 as of this writing.
• The retrieval module now has the ability to create the correction factors (for temperature and dew point) referred to above. The relevant new command buttons are 'Set as Earliest Date', 'Auto Select', and 'Omit'.
• New blue text help items have been added in wxsim.exe and wret.exe to explain the new learned bias correction features.
• A change was made to wret.exe's Weather Display log file parsing mode, to handle uncommon log files which omit decimal points in zero rainfall values. Previously, this could trigger an error at line 578. Also, reading of values with commas as decimal separators was more widely enabled, hopefully avoiding some occasional errors.
• Minor cosmetic changes were made.
• WXSIMATE no longer downloads NGM FOUS or NGM MOS, as these no longer exist as of March 3, 2009. You can still import them into WXSIM from old data files in case you ever want to dorun retrospective historical runs.
  

Version 12.4.5 (January 17, 2009) had the following changes relative to Version 12.4.4 (described below):

• A bug in the TTAA (RAOB) parsing system, which could occasionally result in bad sounding data, has been fixed. This error involved reading a wind field with a direction of 300 or 305 as a height field for the 300 mb level.
• TTAA parsing was improved to read wind speeds of over 100 knots.
• The range of the temperature controls below the sounding on the upper air form has been increased from +/-20 Celsius degrees to +/-35. The previous range had allowed occasional invalid property value errors (#380) in extreme weather, when 1-Click was pressed, or in auto run.
• An attempt was made to eliminate errors, mainly overflow (#6), occasionally seen when wret.exe is called in auto run or by clicking the Repeat button. Specifically, some DoEvents commands were added to the code, to hopefully get Windows to handle events completely, in the order the code attempts to execute them. Feedback on whether this attempt was successful would be helpful, as I cannot seem to replicate the errors.
  

Version 12.4.4 (January 16, 2009) had the following changes relative to Version 12.4.3 (described below):

• A typo in wret.exe's sounding plots was corrected ('850-500 mb thickness' was changed to '1000-850 mb thickness').
• Even more safeguards were instituted to prevent loss of import file name. Note that if the name is somehow temporarily lost, the replacement name will be c:\wxsim\wdata.txt, so that is a good name to use anyway.
• A new check box, labeled 'ext boot', was added to the Output form as an option under 'Graphic'. If checked, wret.exe will NOT be run (as it normally would be to make graphics in auto run or right after clicking "Repeat'); instead wret.exe will simply be prepared to make the graphics and close the next time it is booted, either manually or by an external program such as System Scheduler. The reason for this option is an elusive (perhaps dependent on some unknown condition in Windows) error (#6, Overflow) that some users have encountered at times. This new check box provides an alternative way to automatically generate the same plots and soundings. The help files were also updated accordingly.
• The diagnostic file replog.txt, which was used to narrow down possible causes of the Overflow error described above, was omitted.

Version 12.4.3 (January 14, 2009) had the following changes relative to Version 12.4.2 (described below):

• More protections were instituted against loss of import file name.
• A bug capable of causing an 'index out of bounds of array' error, especially in subfreezing weather at sites near sea level, was fixed.
• The retrieval module's sounding bitmap naming convention was changed to simple serial numbers, instead of skipping. You can still specify a skip interval to determine which soundings are produced, but the numbering is now simpler.
  

Version 12.4.2 (January 13, 2009) had the following changes relative to Version 12.4.1 (described below):

• Further work was done to prevent erroneous reports of missing initial surface data.
• Additional protections were instituted against loss of import file name and settings.
  

Version 12.4.1 (January 12, 2009) had the following changes relative to Version 12.4 (described below):

• A bug (accidentally introduced in 12.4) which caused occasional repeated lines of text on the output page has been fixed.
• Another bug, which caused an erroneous report of missing initial surface data, has been fixed.
• A change was made to further ensure preservation of import file names in the event of errors, including the file not being found.
• A new log file, called replog.txt, was introduced into the code associated with the Output form's Repeat button, to help track down the cause of a reported overflow error (#6) which I have not been able to replicate. Any users who encounter this error should send this file to eburger@aol.com.
  

Version 12.4 (January 8, 2009) had the following changes relative to Version 12.3 (described below):

• Snow level was added as an output, in menu option #8, in the plain text output and as an output to .wxf files. This item is calculated by working downwards through the atmosphere until the first freezing level is found, and integrating temperature above freezing with respct to height until an amount of melting energy, based on the precipitation rate, in encountered. The heavier precipitation, the further below the freezing level it melts. Snow level is defined here as the level at which a large majority (perhaps 90 percent) of the precipitation is snow, though this is a difficult and somewhat uncertain variable to calculate anyway. However, it should still be quite useful for users in mountainous areas. Display parameters can be set on the new, expanded version of the fog sensitivity form, under.
• The precipitation type algorithm was tweaked in light of further research and to better coordinate with the new snow level output.
• Slight changes were made to the melting effect of frozen precipitation. This cooling was reduced by about 10% for sno or snow/rain mixtures. Also, an error which reversed the melting effects of 'snow/rain' and 'rain/snow' was corrected.
• The latest.csv file (and any archived or saved versions of it) has been augmented to include freezing level and snow level. These are listed on the far right side.
• The retrieval module, wret.exe, was expanded to accommodate snow level, which is now displayed in the 'thickness' category. The graphical displays in this category are now more precisely labeled on the plots.
• The sounding plots in the retrieval module were changed to include snow level, and also to display height, temperature, and pressure on the graph at the tip of the mouse cursor, to enable more precise examination of the sounding.
• The retrieval module now allows production of bitmaps of soundings, by checking both the 'Save Bitmap' and 'Inc Soundings' boxes on the Plots form.
• The retrieval module's bitmaps are now cropped to reduce the size. They can be converted to other formats, such as png, by using a third-party program such as IrfanView (www.irfanview.net).
• Changes were made to reduce the likelihood of an error (other than File not Found or Bad File Name or Number) causing a deletion of the name of the file to import.
  GFS data consisting of zeros (as may happen if that system fails to actually parse the data) is now treated as being simply absent. This may reduce the possibility of any errors resulting from such an event.
• Additional notations have been added to the plain text output to indicate when WXSIM fails to find various data types - such as GFS, READY, or METAR, SYNOP, or local station data - to serve as a warning of possible inaccuracy in the forecast.
• An error log (wretlog.txt) was created for the retrieval module (wret.exe) to help diagnose any future errors occurring in that program.

Version 12.3 (November 30, 2008) had the following changes relative to Version 12.2 (described below):

• The boot up default values for wind speed, haze, and level 2 and 4 cloud cover now represent rough climatological normals for the site. Also, if no temperature data is manually entered or imported (via METAR, SYNOP, or from local station data), temperature and dew point will default to climatological normals for that time of day under the given wind and cloud conditions. This makes more reasonable auto forecasts in the rare cases in which data is missing. It also allows for easy production of climatological normal temperature curves in a research or educational mode.
• Handling of date formats is now more versatile, allowing use of yyyy-mm-dd format (used in Sweden, Poland, and perhaps some other places). There are still only two format choices (month/day/year and day/month/year) under Preferences, but WXSIM will now at least correctly populate the entry form on boot-up regardless of Windows regional settings.
• A bug which caused errors and loss of import form settings, after failure to find GFS or READY data in auto mode, has been fixed. In auto mode, no warning will appear to alert the user to the lack of data, but a message will be included in the latestlog.txt file (and the forecast may be rather monotonous).
  

Version 12.2 (November 12, 2008) had the following changes relative to Version 12.1 (described below):

• A new feature was added (on the Interrupt Planner) for specifying the number of hours permitted to pass between advection prompts. This is intended to facilitate updates to advection data (mainly using MOS, which is available only for North American sites) in cases where wind shifts remain below the specified tolerance. A good default figure is about 30 hours.
• An option was added (on the Output Form) to specify saving of only the .wxf files when archiving forecasts. This is intended to minimize disk space usage for users archiving large numbers of forecasts. Manually saved forecasts will continue to be saved as all five file types even when automatically archived forecasts aren't.
• Improved error handling and messages have been provided for the case of clicking 'Get Data' on the Import form with a blank or non-existent file name in the box.
  

Version 12.1 (October 4, 2008) had the following changes relative to Version 12.0 (described below):

• A problem, which could produce 'Invalid property value' errors after importing home weather station data showing very heavy rain, has been corrected.
• A new safeguard was added, against bad METAR wind speeds imported during autorun (for the home site). It defaults them to 7 (mi/hr, km/hr, or whatever your units are), though this can then be overwritten with your own local station data.

Version 12.0 (July 23, 2008) had the following changes relative to Version 11.8.7 (described below):

• Slightly increased thresholds for mentioning fog in the plain text output.
• Expanded use of 'slight chance of' precipitation to include the lower part of the range previously covered by 'chance of'.
• Added an option (under Preferences, along with the existing minimum UV index threshold) for omitting mention of very light or low probability precipitation from the plaintext output.
• Added site, date, and time information to the Comments section of saved forecasts.
• Slightly reduced severity of convective bulletin outputs for Northwest European mode (in both wxsim.exe and wret.exe)..
• Added information on some forms, including clarification of the use of certain controls.
• Made numerous changes to facilitate the use of different registration codes for different levels of use: standard and professional.
• Changed the demo cty.fdt file to include just two sites: Atlanta - which illustrates professional mode - and Marks Point, Australia, which shows standard mode.
• Updated price structuring to cover four combinations of mode and of level of customization (basic and enhanced).
• Updated surface and upper air databases used in customizing WXSIM.
• Changed the TM for the intended WXSIM trademark to ® indicated the recent registration of WXSIM with the United States Trademark and Patent Office.

Version 11.8.7 (June 27, 2008) had the following changes relative to Version 11.8.6 (described below):

• Added the ability to read Dobson unit values for up to 10 days, to be used in UV index calculations. These values can be obtained from web sites (see blue text help for Ozone on Data Entry form) and used to create a simple data file. A sample of such a file, dobunitsAtl.txt, is now included in WXSIM's distribution and upgrade packages.
• The UV index algorithm now includes reflected radiation off of snow cover, plus some consideration of surface type (forest, grass, desert, etc.).
• Changed the interpolation scheme for determining level 1 temperatures from GFS or READY data, in order to avoid some bad results that could previously occur when surface pressures are very low.
• Made forecast log show correct version number.
• Allowed for comma as the decimal separator in the Distance Ratio item on the Advection form.

Version 11.8.6 (February 23, 2008) had the following changes relative to Version 11.8.5 (described below):

• MOS advection in auto run after wind shifts now defaults to using smooth curve fit, with 'enforce monotone' if you so chose on the Auto Run form. Previously, it defaulted to a best fit line, which appears to have subdued temperature advection after sharp frontal passages too much.
• The retrieval module (wret.exe, accessible from the main program via File/Retrieve) now enables comparison of previous forecast with Ambient's Virtual Weather Station software, in addition to Weather Display and WeatherLink.
• The help files were updated to reflect the above changes.
  

Version 11.8.5 (January 21, 2008) had the following changes relative to Version 11.8.4 (described below):

• The suffix 'NDV' (No Directional Variation) is now understood by the METAR parsing routine, as applied to visibility reports.
• The 'maximum distance' value (which you can control with a scroll bar on the Advection form) now applies to the cutoff time for advection (when you can choose to continue with a decay). Previously the maximum distance simply determined which points to leave out of the curve fit. This change should help limit temperature excursions in cases of sparse, inappropriately fit data, especially in auto run, when you are not there to oversee the profile.
• The auto run form has a new check box option for enforcing the monotone condition on smooth curve fits in initial regional data advection in auto run mode. Otherwise, WXSIM decides between monotone and not monotone fits based on the amount of temperature inversion, with monotone applied only if a significant inversion exists. As in (2) above, this change is intended to reduce strongly curved advection profiles, which can result from sparse data (such as near coasts).
• The help files were updated to reflect (2) and (3) above, and generally explain auto run advection options better.
  

Version 11.8.4 (January 14, 2008) had the following changes relative to Version 11.8.3 (described below):

• Checks were added to prevent use of regional data advection in auto run mode when no sites (METAR, SYNOP, or MOS) are found more than one fifth the maximum advection site distance (which you can set on the Advection form). This should prevent some unrealistic temperature excursions that were occurring in auto run, mainly for some near-coastal sites.
• Regional data advection is now weakened in cases of poor flow curvature fits. Specifically, flow fits of 90 percent or better remain as they were. Flow fits below 90 percent are weakened in such a way that, for example, a 45 percent fit now has 71 percent as much effect as previously.
• The message box saying that MOS data has run out now appears even if the user makes repeated attempts to use this data; previously it had appeared only the first time). In such cases, the Import form is now closed to allow immediate access to the Advection for, to allow a new choice.
• The "sleet/mix" precipitation type no longer contributes to above ground freezing rain accumulation.
• The summary.txt file is now saved in the directory in which WXSIM was first booted up (usually c:\wxsim), which could in some cases be different from the current directory at the time the file is saved.
• The version number in the log file was updated to 11.8.4 (it had been left as 11.8.2 in Version 11.8.3).

Version 11.8.3 (December 27, 2007) had the following changes relative to Version 11.8.2 (described below):

• The auto haze routine was improved based on a recent analysis of up to 25 years of visibility data for a few U.S. cities. Generally, the haze amount is somewhat less sensitive to wind speed and recent precipitation than before. Also, a new algorithm allows the initial (input or imported) visibility and associated haze value to decay towards the auto haze amount, rather than abruptly changing to it.
• A new output file, called summary.txt, is now produced with each forecast and placed in the directory with WXSIM. This file is a copy of the "Summary" , "Supplemental data", "Nightime lows and daytime highs", and "Totals" which appear in the original forecast.
• The criteria for the plaintext output's phrases "temperatures rising after midnight" and "temperatures falling in the afternoon" have been changed slightly, so that average temperatures must rise or fall by at least 0.3 Celsius degrees (0.54 Fahrenheit degrees) to trigger inclusion of these phrases. This will prevent the phrases from appearing when temperatures are almost steady.

Version 11.8.2 (December 1, 2007) had the following changes relative to Version 11.8.1 (described below):

• A bug, preventing second and subsequent scheduled auto runs with WXSIM remaining open, had appeared first in version 11.8. This resulted from a mismatch between a timer in the program and the way it was being read. It has been fixed.
• A bug which prevented MOS data from being read on the first try after a "MOS not started yet" message, has been fixed.
• Additional diagnostic items were added to the log file.
  

Version 11.8.1 (November 25, 2007) had the following changes relative to Version 11.8 (described below):

• A bug introduced by a changed yesterday was fixed. In particular, users with day/month/year format would see an error message about the month being greater than 12 pop up incorrectly. The protection feature still exists, but the problem at boot up has been eliminated.
• Additional small changes were made to prepare for the multi-site controller under development.
  

Version 11.8 (November 24, 2007) had the following changes relative to Version 11.7.3 (described below):

• The algorithm for interpreting FOUS relative humidities as cloud cover was modified for the second time this year (see item #5 for Version 11.7.3, below). Specifically, in light of about two months of additional data, cloud cover was increased slightly - about halfway back to what it had been before Version 11.7.3.
• Based on data from many users, including several months' worth that I had collected this year, a change was made to make spring slightly warmer and fall slightly cooler than before.
• Also based on the data above, slight changes were made affecting the shape of the diurnal temperature curve. The main effect that the afternoon high temperature will occur about 10 minutes later.
• Based partly on the data above, and also on an extensive review of verification statistics for the GFS model since the former "parallel" version became the operational (and improved) one on May 1, 2007, the default model temperature bias adjustment was changed from +1.0 to +0.5. The blue text help for that item was also changed to reflect this. Official GFS verification data can be found at STATS
• The program version number is now included in the log files. Also, most error messages will now be recorded in these log files.
• An error message will now inform the user if an attempt is made to enter a date with a month number greater than 12. This should catch most instances of entering day/month/year dates when the format under Preferences is month/day/year. If this occurs, the usually solution would be to change to the date format you want under Preferences.
• A rare error in the routines for determining how old RAOB or READY/GFS data is has been corrected. Specifically, in earlier versions, a forecast start time between midnight and 1 AM, using daylight savings time, was interpreted by these routines as belonging to the previous day. WXSIM now understands the distinction and should determine the ages of these data blocks properly.
• Non-visible changes now enable use with a third program (in addition to WXSIM and WXSIMATE), currently under development, for sequentially running forecasts for multiple sites.
• A customizable adjustment was added to account for variations in the evening temperature curve. Most sites will not need this, but for a few future sites it may improve temperature forecasts slightly.
• Two minor bug fixes, involving inconsistency between scrolling and clicking the default frontal codes scroll bar, were fixed.
• A quick start guide (for both WXSIM and WXSIMATE), illustrated and in either PDF or Microsoft Word format, is now available from www.wxsim.com/downloads.
  

Version 11.7.3 (August 18, 2007) had the following changes relative to Version 11.7.2 (described below):

• A bug - which could cause an "overflow" error (error #6) when the Multi-Curve smoothing option was enacted with insufficient regional data - was corrected.
• A bug - which could cause an "invalid use of null" error (error #94) when using FOUS without precipitation simulataneuously with READY/GFS data - has been corrected.
• Latest.txt (and any name under which you choose to save a forecast) now will contain complete data even if the "TEXT BOX FULL" message appears on the screen. (That message is not an error, but simply results from Visual Basic's 32 KB text box size limit, and can be avoided by choosing either a shorter forecast or a longer output time interval).
• A couple of typographical or formatting errors in the introctory material were corrected.
• Changes were made in the way WXSIM uses FOUS data to predict cloud cover. These changes were based on a careful study forecast versus actual solar radiation in over 100 forecasts, including 55 re-run forecasts after modifications. The previous algorithm, based on comparison of FOUS relative humidities with METAR reports, had resulted in too-thick cloud cover and too-low solar radiation forecasts, which led to reduced diurnal temperature range during the first day or two of forecasts for many U.S. users (as elsewhere FOUS is not available). The most significant error had been too-low summer high temperature forecasts. This correction should make FOUS a more dependable and useful adjunct to the GFS or READY component of imported model data.
  

Version 11.7.2 (June 9, 2007) had the following changes relative to Version 11.7.1 (described below):

• A bug which prevented the WXSIM from properly 'remembering' the 'Stop AM Rain' setting was corrected.
• A bug which could cause an error when WXSIM attempted to use 'remembered' Recent Precip settings was corrected.
• The wording of the message box regarding 'Yes/No' refinement(s) still being activated and warning that values must be reset or reviewed (as some may be quite erroneous) has been made more explanatory. This issue is bypassed when using auto run, with old (but possibly no longer correct) data in use.
  

Version 11.7.1 (June 5, 2007) had the following changes relative to Version 11.7 (described below):

• A bug in 11.7, which left temperature and precipitation column headings in the new 'daily.csv' file as 'deg F' and 'inches' when metric units were in use, has been corrected so that they will read 'deg C' and 'mm'.

Version 11.7 (May 31, 2007) had the following changes relative to Version 11.6.1 (described below):

• A new comma separated variable (.csv, capable of being imported into spreadsheets such as Excel) file was introduced, containing a wide variety of data in a daily summary format. This file, whose name ends with 'daily.csv', complements the existing and much larger .csv file containing almost all output data.
• Most of the refinements (in particular: Auto cumuls, auto stratus, auto haze, recent precip, snow/ice cover, recent temps, diurnal breeze, and stop AM rain) now have settings saved on exit. This is really intended for use in auto run mode, as these should ideally be set by the user at run time. To allow the settings to 'stick', the 'Activate scheduler on next boot-up' box must be checked and the 'Use Above Settings' button must be clicked on the Auto Run form. One item that is not saved is the last 24 hours max and min temperatures (which are not recommended for general use, anyway) on the Recent Temperatures form. Also, the message (appearing if not in auto mode with scheduler activated and splash sceen skipped) warning of old diurnal breeze data is separate from the warning about the other refinements.
• Minor cosmetic or instructional changes were made, and a bug resulting from running comparisons in the retrieval module (wret.exe) with bad or 'gappy' WeatherLink data was corrected by changes to WXSIMATE rather than in wxsim.exe or wret.exe.

Version 11.6.1 ( April 7, 2007) had the following changes relative to Version 11.6 (described below):

• A bug was corrected, which had caused an error when data was imported after setting a negative precipitation skew setting in the READY/GFS Bias Factor.
• Meters per second are now displayed as "m/s" instead of "mps".
• The retrieval module (wret.exe) was updated to include the changes in WXSIM's UV index.
• The help file wxsimhelp.doc was updated to include information on the READY/GFS Bias Factors.
  

Version 11.6 (April 6, 2007) had the following changes relative to Version 11.5.1 (described below):

• Model data (READY or GFS) imported to the Interrupt Planner is now subject to bias adjustments on upper temperatures, cloud cover, and precipitation. To access these settings, click the new "REAGDY/GFS Bias Factors" button on the Import form. Settings are saved on exit.
• Default frontal codes now include some consideration of current above or below normal temperatures, so that a "return to upwind normals" assumes that "normal" includes a fraction of the home site's departure from normal. This should make default advection somewhat more accurate than before during periods of abnormal weather, by allowing a bit more persistence of the abnormality.
• The UV Index algorithm was altered based on further study of a variety of sources of data. The general effect will be to lower UV index slightly, mainly with low sun angles.
• The Dobson Units setting on the Entry form is now saved on exit.
• The lower limit for display of UV index in the plain text output is now user-defineable, under Preferences on the Entry form.
• A very slight adjustment was made in the program, producing a barely noticeable increase in spring temperatures and drop in autumn temperatures.
• An adjustment was made in the program to lower dew points very slightly, based on a consensus of user feedback.
• A rare bug - in which an infinite loop error when negative wind speed in advection sites was encountered - was corrected. Such erroneous winds are now set to zero.
• A bug, resulting in an "Invalid Use of Null" error message and occurring with initial precipitation, was corrected.
• The "No data found for these sites" message during auto mode has now been more thoroughly suppressed (see #5 under Version 11.5.1, below).
  

Version 11.5.1 (March 3, 2007) had the following changes relative to Version 11.5 (described below):

• The precipitation description “MIX” now no longer leads to mention of freezing rain in the plain text output unless the temperature was actually below freezing at the time.
• Initial snow cover is no longer included in the first period accumulation in the plain text output.
• A bug, which kept snow accumulation units on the snow/ice cover entry form from properly switching between centimeters and inches, has been corrected.
• The isolated METAR signifier “T1” now will not be mistaken for the first two characters of an extended temperature field (which can also start with those two characters).
• (The “No data found for these sites” message (after attempting to import regional advection sites) has been suppressed while in auto mode. In this case advection will default to either ‘Default (frontal codes)’ or ‘Neutral’, according to your earlier specification on the Auto Run form. This should prevent many cases of stalling while in auto run mode.
• Maximum UV index for the day has been added to the plain text output, as long as it exceeds 5.5.
  

Version 11.5 (February 10, 2007) had the following changes relative to Version 11.4 (described below):

• Item #4 in the revisions in Version 11.4, below, was not completely corrected in Version 11.4. A further change was made in 11.5 so that it will work as intended.
• The METAR signifier "NCD" is now recognized, as meaning "no clouds".
• Some changes were made to the FOUS and Interrupt Planner shower options. In particular, the Interrupt Planner showers now fall one third of the time, rather than one fifth (several versions back, it had been one third), but about 9 minutes later, in order to display the precipitation even with one hour output intervals (with one fifth, the showers were often missed in the output). To partially compensate for the slightly reduced daytime highs with the longer showers, the increase in cloud thickness due to precipitation was decreased slightly. Also, FOUS and Interrupt Planner showers now work together in a complex, but more accurate (than before) manner.
• A minor bug, involving cloud thickness after precipitation, was corrected.
• Minor cosmetic changes were made.
• Slight tweaks were made to the advection routine and the diurnal range. The only noticeable difference should be a slight reduction in the initial strength of advection (or in cases of very steep temperature gradients), generally amounting to about one or possibly two degrese Fahrenheit warming at 12-24 hours in strong cold air advection, for example. These changes were made after extensive testing on historical and recent operational data in Atlanta, plus consideration of feedback from users in other regions.
• A change was made in the default frontal codes routine to slightly decrease temperature gradients. This probably now makes the default frontal code option superior to neutral advection after wind shifts, when no MOS data is available.
• The Help item on the Data Entry form is now more informative, including mention of the wxsimhelp.doc file, where all the blue-text help items are presented in an organized form.

Version 11.4 was (December 30, 2006) had the following changes relative to Version 11.3 (described below):

• There is now an option on the Auto Run dialog form allowing the the Scheduler to activate on the next boot-up of WXSIM. This allows starting by an external program, such as System Scheduler, skipping the start-up splash screen, and going straight into auto run mode.
• A log file (latestlog.txt) is automatically created with each run, showing virtually all significant user actions (and some program-directed ones). This is intended mainly for diagnosis of problems, but can also serve as a simple record of how the run was made, especially as it is archived and time stamped if you choose to archive the forecast.
• The menu item 'Customize' was renamed 'Preferences', to avoid confusion with the customization process involved with program registration.
• Auto run now distinguishes between lack of MOS data on wind shifts due to being before, versus after, the start of the data. Now it will read MOS in spite of an earlier finding that it hasn't started yet.
• Precipitation with chances less than five percent is now not mentioned, either as a weather description, or as a precipitation amount, in the plain text forecast.
• Persistent moderate to dense fog now precludes mention of sky condition in the plain text forecast. This is to avoid such combinations as "Sunny. Dense fog.". Also, a new category, "moderate fog" was added, along with other slight wording changes.
• Several message boxes regarding READY data were modified to include the GFS option.
• If used to import local station data, WXSIMATE now produces a file called locallog.txt, containing the same information it displays in the program itself. Also, wording of some error messages in WXSIMATE has been improved.
  

Version 11.3 (November 8, 2006) had following changes relative to Version 11.2.3 (described below):

• The ability to use GRIB-derived GFS model data - downloaded, processed, and made available on the internet by Chris McMahon - was added. Other changes made to accommodate this were the expansion of the number of interrupts of each item on the interrupt planner from 35 to 62, and the ability for WXSIMATE to download site-specific GFS data for use in WXSIM.
• A couple of related bugs in the retrieval module (wret.exe), which caused high and low temperatures and dates to be shifted relative to each other for forecasts made between 11 PM and midnight, were corrected.
• A bug in the comparison feature of the retrieval module, which caused a failure to properly read home station (Weather Display or WeatherLink) in forecasts spanning two months, was corrected.
• Temperatures and dew points in U.S. METAR reports are now consistently and properly rounded off to whole number Fahrenheit degrees in reports with the extended temperature section. Previously, these would sometimes be reported differently by one tenth of a degree.
• Temperatures and dew points parsed from synoptic data now have leading zeros omitted.
• 24 hour max and min temperatures from local station import are now displayed on the Recent Temperatures form even if they are not checked for use.
  

Version 11.2.3 (October 2, 2006) had following changes relative to Version 11.2.2 (described below):

• Changes were made to accommodate a recent (September 28) change in the READY data’s header. WXSIM can still recognize the older format as well, in case you want to re-run old forecasts.
• A bug, which could allow certain METAR station codes to be read as weather type abbreviations, was corrected.

Version 11.2.2 (August 19, 2006) had the following changes relative to Version 11.2.1 (described below):

• A bug, resulting from the addition of a few incomplete entries to the NWS's MOS data files, has been fixed. This had caused a 'Bad sky cover data' message box during MOS import for advection. WXSIM now ignores these non-standard MOS entries.
• Any actual bad sky cover data now encountered will default to partly cloudy, instead of clear.
  

Version 11.2.1 (August 17, 2006) had the following changes relative to Version 11.2 (described below):

• A bug, which caused the plain text output wind direction to always be 'north' when the diurnal breeze routine was in effect, has been fixed.

Version 11.2 (August 12, 2006) had the following changes relative to Version 11.1 (described below):

• A bug in the retrieval module, which prevented changing the directory for Weather Display forecast comparison, has been fixed.

Version 11.1 (August 11, 2006) had the following changes relative to Version 11.0.2 (described below):

• The retrieval module's comparison feature was expanded to include input from Davis WeatherLink files, via a new feature in WXSIMATE which saved files in text format as they are read for local station import.
• The ability was added to list the files being compared and/or combined in the retrieval module.
• Compared and/or combined data in the retrieval module in the retrieval module can now be saved as a spreadsheet-viewable .csv file.
• The 'Combine' check box now maintains its state (checked or unchecked) between comparison retrievals in the retrieval module.
• The second weather text item now appears in WXSIM's saved forecast .csv files (it was intended to appear in earlier versions, but failed to).
• The column headings in WXSIM's saved .csv files are now left-justified (instead of right-justified), to make them more visible.
• Enabled printing of plain text forecast with 'Graph and Summaries' option (in addition to the other options).
• A bug, which could cause repeated dates when retrieving forecasts made using daylight savings time, was fixed.

Version 11.0.2 (August 5, 2006) and has the following changes relative to Version 11.0.1 (described below):

• A bug, which kept files from being archived properly when the 'Quit' button was used, was corrected.

Version 11.0.1 ( August 2, 2006) had the following changes relative to Version 11.0 (described below):

• A bug was fixed in wret.exe, which had caused occasional scale problems when viewing comparison plots of relative humidity.
• On the form for naming saved forecasts, the default name was changed from 'latest to latest (leading apostrophe removed).

Version 11.0 (July 25, 2006) had the following changes relative to Version 10.6 (described below):

• An Auto Run option (under the Start menu) has been added, allowing almost all features of WXSIM to be used either for an immediate run or at user-prescribed times. In conjunction with these changes, WXSIMATE can now import data at prescheduled times as well, and the retrieval module, wret.exe, can be set for brief automatic boot-ups and shut-downs to save bitmap graphics of forecast plots.
• A plain text forecast, with wording somewhat similar to zone forecasts from the U.S. National Weather Service, now appears at the end of the previous text output, and is also saved as a file called "plaintext.txt".
• A global warming option (with the option to switch on or off under the Customize menu) has been added. It affects customized climate data, the world climate data grid, and radiative properties in the program itself. It is normalized to approximately the year 1995, meaning dates with that year will have neutral effect.
• The default frontal codes algorithms were improved using a large amount of climate data for several U.S. cities.
• The precipitation probability algorithms were improved by mixing the existing routine with another, seasonally-dependent estimate using the relationship between amount of predicted precipitation and the probability of any measurable amount actually occurring. This relationship was derived from both historical climate data from several U.S. cities and results from about 400 forecast-days in Atlanta.
• An option was added to the retrieval module (wret.exe) to allow comparison of previous forecast data with actual data logged on home weather stations. Currently it requires the use of Brian Hamilton's Weather Display program's log files, but I hope at some point to add support for Davis WeatherLink .wlk files as well. A great deal of statistical data can be gleaned from this feature, which may help with future customizations and, in some cases, possible tweaks of existing ones.
• A problem with parsing certain Italian METARs was corrected.
• WXSIM's Daylight Savings Time check box's contents are now saved for the next boot-up.
• Several aspects of FOUS use are better handled now, including dependable disabling of the routine if no data was imported, and saving of settings for the next boot-up. FOUS can also now produce more than one wind shift if allowed to do the first one.
• The Search routine on the Advection form now properly imports MOS (instead of METAR) as the default after wind shifts and correctly resets the number of sites found to zero in between searches.
• A new, optional setting allows automatic archiving of forecast data files, using the format fyymmddhh in front of the .txt., .csv, and .wxf formats. A similar setting in WXSIMATE allows archiving of data files in the format dyymmddhh.txt.
• The retrieval program now automatically defaults to the file latest.wxf on boot-up, though you can change the file to any forecast you've made, as before.
• The apostrophe in front of the default saved file name "latest" has been removed, as has the one in front of the retrieved data file name "lastret".
• WXSIMATE can now import local station data over the internet, given a root URL as the path.
• A couple of background bugs (including a redundant variable name) were corrected.
• Various minor cosmetic and documentation changes were made to all three programs: wxsim.exe, wret.exe, and wxsimate.exe.
• The help files and manual were updated to reflect changes.
• A copy of the custinit.txt file (which contains your personal boot-up settings for WXSIM) is saved, as custinitbak.txt, in case the file ever gets corrupted or you wish to return to the settings you had before a run. To restore the previous values you would simply rename custinitbak.txt to custinit.txt.
  

Version 10.6 (January 23, 2006) and has the following changes relative to Version 10.5 (described below):

• All of the slider controls were changed to horizontal scroll bars, thus reverting to the form in all versions prior to 10.0. There are two reasons for this. First, and most importantly, I learned that installation of Microsoft Office XP or MS Office 03 apparently deletes (from Windows/System32) the comctl32.ocx which the slider control requires, thus leading to an error in WXSIM. By switching to the scroll bars, this error should be avoided. Second, the scroll bars allow finer control of the values they represent.
• A rarely encountered bug, in which RAOB data segments could be mistakenly read as buoy data (if the digits happened to be the same as the WMO synoptic code of the buoy), has been fixed.
• Minor cosmetic changes were made in a few places.
  

Version 10.5 (January 16, 2006) had the following changes relative to Version 10.4 (described below):

• A new control, for 'Maximum Distance' was added to the advection form. This allows you to limit consideration of advection site data to only those less than the upwind distance you specify. In particular, this applies to the various smoothing routines (working on data points from Regional Data, Two Upwind Sites, Frontal Codes, and Direct Click) and also to the speed ('Spd') and flow fit ('%') figures found above the 'Search' button. The straight line (segment) fit is unaffected.
• The 'Difficulty reconciling total cloud cover with upper level relative humidities' message had been coming up too often. This is because the GFS READY meteogram data always seems to start with .000 as the cloud cover, before becoming reasonable with the very next report. WXSIM now overlooks the problem if it occurs only on the first entry (which has little effect on the output).
• I discovered that the (rarely used) 'Two Upwind Sites' advection option was not functioning. This has been corrected.
• Minor cosmetic changes were made to the retrieval module, wret.exe.
• Blue clickable page numbers were added to the Table of Contents of this manual to allow instant jumps to specific topics.
  

Version 10.4 (December 29, 2005) had the following changes relative to Version 10.3 (described below):

• The handling of level 1 temperatures entered on or imported to the Interrupt Planner was improved. Formerly, the values were interpreted as actual level 1 temperatures. This is still the case if you clicked them in yourself, but now READY-based temperatures take into account the actual pressure level(s) (i.e. 925 mb) and adjust accordingly to the level 1 pressure in WXSIM at the time.
• A set of options for use of level 1 temperatures (see above) was added. Now the temperatures can be ignored ("0%"), so that WXSIM's own routines are in charge, they can be fully used ("100%") so that WXSIM will follow them very closely, or they can be partially considered ("50%") so that WXSIM uses a compromise between its native figures and those from the Interrupt Planner. My current thinking is that the "50%" option may be best on average. However, this is a new option and I am not yet sure if it will be truly advantageous. It does *not* always yield temperatures halfway between the other two options.
• A bug was fixed involving the Diurnal Breeze option. In the original changeover to versions 10.6, an oversight left the Mountain/Valley Breeze routine out of consideration for the default diurnal breeze (the other option being Sea Breeze, which is the default unless your customization contains specific topographic data for the Mountain/Valley Breeze). This has been corrected.
• A slight change was made to the interpretation of FOUS and READY based winds. In particular, non-100% wind correction factors now use slightly different factors for winds of different speeds. Light winds (below about 9 mph) are adjusted by relatively larger amounts than are stronger winds. This change was motivated by my experience that wind speed differences are best characterized as a sort of mix of additive and multiplicative corrections. Places averaging 80% of standard winds, for example, might show 7.2 mph (80%) when standard winds are 9 mph, but 3.5 mph when standard winds are 5 mph (70%) and 17 mph when standard winds are 20 mph (85%).
• A message box was added to warn against use of METAR or SYNOP surface data for advection, after the forecast run has already started, such as after a wind shift interrupt. Such use was formerly discouraged only by the automatic switch to MOS as the default source for regional data advection. METAR and SYNOP import at this point are still allowed, but should be used only rarely, for instance in cases of almost immediate wind shifts (i.e. an hour or two into the forecast run).
• Various minor cosmetic changes were made, mainly to some text boxes which weren't wide enough to hold some of the values that might be encountered.
  

Version 10.3 (November 23, 2005) had the following changes relative to Version 10.2 (described below):

• A new option was added to the regional advection data routine choices. This is 'Multi-curve fit', which blends two of the 'Smooth curve' solutions - one for the nearest half of the advection sites and one for the farthest - using a weighted average. The '~Monotone' box can be checked or left unchecked, as it still applies to the far-half smooth curve solution.
• A small correction was made to the root-mean-square fit quality output on the advection form's temperature and dew point gradient plot (~monotone had previously included a distant non-site point in the data, slightly altering the values). Also, the gradient plots' internal resolution has been doubled, sometimes leading to slightly more accurate curves..
• Based on further research and testing, changes were made to the temperature and dew point advection routines. The main effect is slight increases in the strength of advection in the stronger advection events.
• Help forms now automatically unload when a new blue-text item is clicked, so that it is not necessary to first click 'OK' to clear the last help item before choosing another one. This change was implemented in both wxsim.exe (the main program) and wret.exe (the retrieval module).
• Minor changes and additions were made to the help files, to accommodate the new advection option.
• A bug was corrected, which had kept the file list box on the Cull/Append form from updating when the directory was changed.
• A few text boxes on the Entry form were widened to accommodate the longer displayed text items, which in some cases had been cut off before.
• The Atlanta sample data in cty.fdt was updated with a newer version, the most significant change being a small increase in the default urban heat island effect (for this site only).
  

Version 10.2 (October 21, 2005) had the following changes relative to Version 10.1 (described below):

• The range of allowed text widths (in both the main program and the retrieval module) was increased to accommodate a very wide range of system conditions.
• A few blue-text help items had ended up with the wrong links during the change from Version 9.6.5 to Version 10.0. These have now been corrected.
• Label name changes from Version 9.6.5 to Version 10.0 had caused incorrect behavior of the red versus blue caption highlighting on the advection form. This has been corrected.
• Problems were discovered in the Import/Cull/Append routine. This caused in some cases severe limitation of the number of METAR or SYNOP sites culled from downloaded data. This has been corrected. NOTE: This is an old routine, whose functionality and speed have been greatly surpassed by similar abilities in the WXSIMATE program.
• A new document, WXSIMHELP.DOC, has been included in the package. This conveniently displays for direct reading all of the information in the blue-text help file help2.txt. Many thanks to Fred van den Bosch for this idea and for organizing it into this format.
  

Version 10.1 (August 27, 2005) had the following changes relative to Version 10.0 (described below):

• The location list box was widened (country names were partially cut off in 10.0).
• UV index is now rounded off to tenths for all sun altitudes.
• Slight cosmetic changes were made.
• It was discovered that, despite a message to saying the program was defaulting to Atlanta, users without registration codes were still able to access their home sites. This has been corrected, so that the code - obtainable by paying the upgrade fee - is now required. (The upgrade to 10.0 was a lot of work!).
• Two new items have been added to the 'Other Data' section of the retrieval module: % Sky Cover (Lev 1, 2) and Wind Direction. The new sky cover item compliments the existing % Total Sky Cover item (which combines levels 1-5) by displaying the combined coverage of just those clouds in levels 1 and 2. The wind direction item allows plotting of wind direction at all forecast times, instead of just the few times a day wind vector 'sticks' (which are still included).
• Updated and corrected some help file items for the retrieval module.
  

Version 10.0 (August 16, 2005) had the following changes relative to Version 9.6.5 (described below):

• The entire program (both the main and retrieval modules) have been converted from the old 16-bit Visual Basic 2 to 32-bit Visual Basic 6. This should give the program a long future of compatibility with upcoming versions of Windows. Backwards compatibility has been maintained so that old data, customizations, and forecasts can be accessed smoothly from the new program. Also, significant speed increases resulted, by a factor of about 1.7, so data imports and forecasts
  take only about 60% as long as before.
• A new registration and custom file access method has been implemented. This allows all users full use of the program in demo mode (i.e. using Atlanta as a default site), while a simple registration code (provided with registration or upgrade fee) unlocks full use of customized sites. Also, the last site used is conveniently the default site at next boot-up.
• The names of the executable files have changed: wxsim.exe replaces the old wxsimw.exe, and wret.exe replaces wxrw1.exe. This allows older versions to coexist in the same directory with the new ones, in case you ever want to compare output or performance.
• The forecast saving routine has been changed. Now, all forecasts are automatically saved as 'latest, and the save is applied AFTER the forecast run (like most first time users seem to expect). There is also a new button on the output form to allow for convenient saving of forecasts right after a run. Furthermore, there is a warning if you try to overwrite an existing file.
• A very carefully calibrated correction has been made for some subtle temperature biases I discovered. Specifically, there will be a tendency, as compared with earlier versions, for cloudy days in summer to be warmer, cloudy days in winter to be cooler. Clear days at all times of year should be very similar to before, with perhaps a trivially smaller diurnal range.
• Numerous cosmetic changes, including replacement of many 'scroll bars' with 'sliders', particularly with wind direction, relative humidity, and cloud cover, where the tick marks are particularly appropriate.
• Added wind arrow graphics to help user visualize the entered wind direction.
• Added level 1 temperature as a variable for the Interrupt Planner and READY input.
• Added adjustment '+' and '-' buttons the Interrupt Planner to allow quick raising or lowering
  of all values of the chosen planned (or imported) item.
• Modified the low level mixing routine to reduce the likelihood of superadiabatic lapse rates between the surface and level 1.
• Changed the Interrupt Planner's saved-file retrieval form so that it now indicates only files with extension .pln.
• Improved formatting of printouts in all modules.
• Slightly reduced the diurnal variation of thickness and temperatures on the Interrupt Planner.
• Added three new message boxes to warn (mainly) new users who fail to make use of FOUS, upper air, and/or READY data, and give them a second chance to use the data if they like. Also, provided more explanation in the 'Visibility uncertain …' message box.
• Changed the METAR pressure import algorithm to avoid a bug which could incorrectly show a station pressure as a surface pressure. Also changed both this and the corresponding synoptic import routine to ensure precision to 0.1 mb (previously, round -off errors were possible).
• Changed METAR routine to allow more reports with some missing data, such as winds. This may increase the number of advection sites available for use.

(Note: the next 7 items are specific to the data retrieval module, wret.exe)

• Corrected various problems associated with use of Daylight Savings Time, including a situation in which the text output would repeat the same day of the week as the heading.
• Enhanced the data saving routine so that actual 24 hour and AM/PM extreme temperatures are recorded for later retrieval with wret.exe. (The old wxrw1.exe will not properly read these new files, but the new wret.exe can read the old ones).
• Correction of a bug which had caused the dates to line up wrong on plots of forecasts initialized just before midnight, and had also caused the text output to sometimes repeat the same day of the week over and over.
• Added the WXSIM version number (10.0) to the caption of the main form.
• Added AM lows/PM highs to the plots (for new forecasts) and enabled use of the new data (see (2) above)) saved by wxsim.exe.
• Corrected a bug which could confuse the program's determination of the mouse position on the plots after a printout command.
• Corrected a small bug in the plotting routine which would combine all precipitation before the first day displayed with the first day's precipitation.
  

Version 9.6.5 (May 21, 2005) had the following changes relative to Version 9.6.4 (described below):

• A bug, which occasionally produced an overflow error during import of advection data (probably only with advection map at the closest zoom setting), has been corrected.
• A message box, instructing the user to return to neutral advection setting before importing regioanl advection data after a flow curvature change, has been added in a more appropriate place than before.
  

Version 9.6.4 (April 23, 2005) had the following changes relative to Version 9.6.3 (described below):

• A newly encountered format of METAR data (with "$" signs connecting separate reports) triggered an error in previous versions. This has been corrected, and the first METAR report of such a string will now be read.
• Inappropriate triggering (such as when the error discussed above occured) of a 'file not found' error message was corrected. If future errors occur, they should now be properly identified in such messages.
  

Version 9.6.3 (March 25, 2005) had the following changes relative to Version 9.6.2 (described below):

• Error trapping and data quality control were improved for barometric pressure entries.
• Minor information changes were made to two forms.
  

Version 9.6.2 (March 21, 2005) had the following changes relative to Version 9.6.1 (described below):

• A problem reading certain METAR reports (in particular, Italian ones with an empty wind group "/////KT") was corrected.
• An additional minor change was made which should slightly increase the speed of the METAR and SYNOP search routines.

Version 9.6.1 (March 20, 2005) had the following changes relative to Version 9.6 (described below):

• A bug introduced in Version 9.6 was corrected. This bug had caused an error message when attempting to use the Diurnal Breeze routine.
• Two types of weather descriptions were added to the new (with Version 9.6) commas separated variable files.
  

Version 9.6 (March 19, 2005) had the following changes relative to Version 9.5.1 (described below):

• A new export file type was added: comma separated variable (.csv), which can be imported into spreadsheet programs for users who wish to do their own types of analysis and archiving. The name of the file (before the extension) is the same as for the .wxf and .txt files already available.
• A few new error traps and message boxes were added. One concerns the above-mentioned files, and prevents errors resulting from trying to open file names which are currently in use by other programs. Another is on the Advection form, where new message boxes help prevent usage errors (which would not otherwise stop the program, but would degrade the forecast) such as failing to 'Use' imported data, or failing to re-import after curved-flow adjustments.
• Small improvements of the help file were made.
• A couple of minor cosmetic and informational changes were made.
  

Version 9.5.1 (January 26, 2005) had the following changes relative to Version 9.5 (described below):

• The extended advection map data, including information for coloring water blue, was inadvertantly omitted from at least some of the recently released packages (probably startng with Version 9.3). They are included now.
• NOAA just changed the ETA model's name to NAM. WXSIM can now handle this, and is still able to import old ETA data as well. All references to 'ETA' in the help files were also changed to 'NAM'.
• Small changes in the documentation were made, including the option of paying for WXSIM or WXSIMATE via PayPal.

Version 9.5 (December 29, 2004) had the following changes relative to Version 9.4 (described below):

• Minimum and maximum relative humidity for each day was added to the 'Summary' output. Similarly, average relative humidity for all complete days was added to the 'Totals'.
• Spacing between numbers was improved in the 'AM Lows and PM Highs' output, so that the values would more dependably line up underneath the day headings, even in the case of single digit values (common when using Celsius in winter). The same correction was applied to the Retrieval module.
• Minor cosmetic changes were made to both the main module and the retrieval module.
• Minor changes were made in the help files for both the main module and the retrieval module.
• A change was made to accomodate 'FW' (few clouds) as a sky cover type in the MOS parsing routine. (When encountered previously, this had triggered a message which said 'Bad sky cover data. Assuming clear.')

Version 9.4 (December 14, 2004) had the following changes relative to Version 9.3 (described below):

• The text box for the name of the data file to be imported has now been enabled, meaning you can now type directly into it as an alternative to selecting it from the drive, directory, and file list boxes below. This may be faster if you save a lot of old data files which you might have to scroll through. Also, an error trap for bad file names has been added.
• A small bug affecting the displayed solar and UV radiation on the Data Entry form has been fixed. This bug had allowed imported READY data to alter to sun angle used in these displays, though the resulting errors never appeared in forecast output.
• Several, mainly cosmetic changes were made, including the wording and positions of the Introduction, Registration and License forms.
• A setup/installation program called setupwxm.exe was created (using Inno Setup), to serve as the primary mode of distribution for this new version. A similar setup program, setupwmt.exe, was created for distribution of WXSIMATE Version 1.4 (compiled on December 10, 2004).

Version 9.3 (December 10, 2004) had the following changes relative to Version 9.2 (described below):

• Changes were made to the algorithm involving the albedo of snow cover. In particular, it was found that the previous version overestimated albedo in cases of dry (relatively treeless) sites. This was improved based on considerable additional study of the effect of snow cover on both minimum and maximum temperatures. One method was climatological studies of surface data, using upper air data to control for overall air mass temperature, for many cities, including Peoria IL, Glasgow MT, Minneapolis MN, Boulder CO, Flagstaff AZ, Nashville TN, and others. Another was study of snow swaths, especially from the heavy February 1973 storm across Georgia and the Carolinas, and also some consideration of a study of Midwestern snow swaths by David Travis, Steve Curran, and Amy Nielsen (see ams.doc
• Changes were made to ensure compatibility of local data import with the latest version (1.3) of WXSIMATE.
• Slight cosmetic changes were made, including a new icon, wider text and list boxes on the Data Import form, and a more thorough explanatory note on the Save Data form.
• An error trap was added to prevent runs with zero barometric pressure (i.e. resulting from incomplete METAR data being imported).

Version 9.2 (October 18, 2004) had the following changes relative to Version 9.1 (described below):

• An option to display precipitation in bar graph form, rather than as color changes of the temperature curve, was added.
• A bug, which could have prevented the mapping routine from making certain sections of the ocean blue, was fixed.
• A bug which read current precipitation rate as much higher than actual, when using local data import from home weather stations (via WXSIMATE), was corrected.
• A more versatile format for the files localcal.txt and localdat.txt (produced by WXSIMATE) was adopted and allowed for in WXSIM, so as to avoid errors that occured in German language Windows settings. This error had resulted from conflicts between periods and commas as decimal points, and is now avoided by storing values as large integers.
• Slight cosmetic changes were made to some forms.

Version 9.1 (July 31, 2004) had the following changes relative to Version 9.0 (described below):

• Improvements were made to the advection map backgrounds. The data now covers the entire world, and some additional details and resolution have been added - mainly large lakes and bays, mainly in North America. Also, bodies of water are now displayed blue (before, all backgrounds were white).
• The program now saves the name of the last imported data file, and displays it as the default the next time you use the program. This can save time in selecting the file for import, especially if you use the same name each time (though if you intend to archive the data, this may not be the best choice).

Version 9.0 (July 7, 2004) had the following changes relative to Version 8.9.1 (described below):

• WXSIM can now use data from a new companion program, WXSIMATE, which can greatly speed and ease collection of data from internet sources, and also allows import of many data types from home weather stations (at this point only those using Davis WeatherLink 5.0 and later). WXSIM can also open WXSIMATE if the latter is present in the same directory.
• The calibration run is now able to use WXSIMATE data to simulate conditions leading up to the present. This may increase forecast accuracy somewhat, especially on days when large changes in cloud cover, wind speed, or precipitation have occured since the last 'midpoint' of the diurnal temperature curve.
• A new 'Refinement' item has been added: "Stop AM Rain". This addresses a problem that has existed ever since WXSIM began using external model data several years ago. In particular, much of the warm season rain in many areas consists of heat-induced afternoon and evening thundershowers. The 3 or 6 hour resolution model data (NGM, ETA, or GFS) as used by WXSIM, however, often started rain in the late morning or early afternoon, prematurely cutting off heating and underforecasting the high temperature. This new option lets you specify the earliest and latest times for rain to occur. Carefully devised location and season-dependent default times are provided, but can be overridden.
• A couple of related bugs involving the Interrupt Planner, particularly when using READY data or clicking changes, have been resolved. These sometimes caused parts of the data to dissapear on subsequent runs.
• Recall of the Monotone and Best Fit check box values, after clicking 'Use Previous' on the advection form, may not have worked properly in some earlier versions. This has been fixed.
• The activation indicator for 'Sea Breeze' at the bottom of the Output form now properly indicates 'Mtn/Vly Breeze' if the mountain/valley breeze routine is in use instead of the sea breeze one.
• A very minor bug was discovered, in which second and later imports of FOUS data would automatically be active without the user authorizing it by clicking the 'Use FOUS' button. Now, any additional FOUS imports must be freshly authorized. Also, the 'Clear' button below the Use FOUS button now says 'Clear FOUS'.
• Several minor cosmetic changes were made to a number of forms, including enlargement of the raw surface data view box accessed from the Import form. Also, the 'Scanning for METAR' message now properly says 'Scanning for MOS' that is the case.
• This is not a change in the program itself, but note that FSU now provides the buoy data formerly available at PSU. The new web address is here
• A bug - which prevented most buoy data in synoptic format from being read - has been corrected. At the same time, the ability was added to distinguish between rare cases in which a buoy had the same identifier (synoptic code) as a land station.
• Missing data (such as dew point) now should show as an 'M' on the advection map and the advection site list box, instead of '0' or '999', which was the case before.
• A minor, rarely encountered bug - in which the program failed to remember the latest choice of synoptic versus METAR as the default surface data type - was corrected.

Version 8.9.1 (January 24, 2004) had the following changes relative to Version 8.9 (described below):

• The 'Search' routine on the Advection form (button next to the anticyclonic/cyclonic flow scroll bar) has been improved. It now more consistently finds an optimum fit to curved flow. It is not any faster than before, and still may occasionally fail to find the absolute best fit, but it usually does quite well. You can still adjust the curved flow manually, as well. The help file was also updated to reflect this change.
• A bug, which caused failure to read READY data out past about the 6th column, has been corrected. WXSIM now reads as many columns as the READY meteogram text routine can produce (10 items, or up to 11 columns if 'wind flags' is selected).
• A wider range of text widths has now been provided, to accommodate practically any computer, settings, and Windows version possible.
• A change was made to avoid problems that could occur if GFSX MOS data was present in a file along with METAR to be imported. In particular, if the GFSX MOS site had the same identifier as a METAR site being searched, the older version would mistake it for METAR data, then crash with a 'Subscript Out of Range' error. This problem has been corrected.
• A typographical error in the algorithm for ultraviolet index was corrected. This error was causing too-low UV index for sun elevations of 15 to 30 degrees, sometimes visible in retrieved data plots as a pair of spikes near the tail ends of the UVI curve. Theses curves will now be much more smooth.
• When the default advection routine ('frontal codes') is chosen, new default values of the frontal code will appear. Before the forecast run, this will be 2 ('gradual turn towards upwind normals'), but on subsequent shifts, either manual or automatic (i.e. due to READY data) a new value will be calculated. This will often be a higher value, suggesting the passage of a front. The most well-defined fronts will be cold fronts indicated by a large shift to a direction from higher latitudes.
• In the retrieval module (wxrw1.exe), adjustments were made to the text output format to allow more details of the 'Weather' text description. Previously, the allowance of only 10 was cutting off the extended information - such as dew, frost, and precipitation type. Now, all data is shown, except that each of the two 10 character parts of the weather description is cropped to 9 characters because of space limitations in printouts.
• The text width range in wxrw1.exe was also increased, partly to accomodate the longer lines of text, but also to provide for a wide range of computer setups.
• A new 'Superimpose' button on the plotted data form in wxrw1.exe now allows plotting of multiple forecasts on the same graph, for comparison. There is also a new check box allowing the user to specify whether or not subsequent plots are to use thicker lines, to distinguish them from earlier ones.
• A minor bug that sometimes caused omissions of convective bulletins in wxrw1.exe's text output was fixed.
• The starting time of a saved forecast was added to the identifying information when selecting a file to view in wxrw1.exe. Also, the text color of this identifying information was changed from gray to black to improve readability.

Version 8.9 (November 8, 2003 had the following changes relative to Version 8.9(described below):

• Most of the commonly viewed forms in both the main program (wxsimw.exe) and the retrieval module (wxrw1.exe) were enlarged significantly, from about 640x480 to 800x600 pixels, allowing much larger graphics and in many cases more space between controls.
• The optical effects of clouds were altered slightly, based mainly on careful studies I did using NOAA's SAMSON data and nearly two solid months of METAR data for KATL correlated with measurements of solar radiation archived every 10 minutes using a Davis Vantage Pro weather station I recently installed at Woodward Academy, where I teach. I also did some analysis of hundreds of forecast I've logged over the years using WXSIM, to see if days with small-medium diurnal ranges (and therefore likely partly to mostly cloudy) had these diurnal ranges suppressed in the forecast; they did, though the effect was slight, but corroborated the need for at least a small change. The main effect of these changes is a modest reduction in the default opacity of clouds (including the auto cumulus and stratus routines as well as clicked and interrupt input and imported METAR or synoptic data), given areal coverage, especially under partly to mostly cloudy skies. Some of the reason for this is consideration of sunlight reflected off the sides of clouds (the cloud gap effect), which had not been previously taken into account. The main effect here is a small (about 1 degree C or nearly 2 degrees F) increase in diurnal range on partly to mostly cloudy days. Another small change is that cirrus clouds now have enhanced reflectivity with lower sun altitudes.
• While doing the studies above, I found that clear days had very slightly too much diurnal range, by perhaps 2% (about half a degree F) on average. Slight changes were made to correct this.
• In conjunction with the studies mentioned above, in (2), solar radiation (visible, in Watts per square meter) was made an output, also saved in .wxf files for use in the retrieval module. The solar radiation is based largely on the Davis data from my school, but also from the SAMSON data, especially a period of actual (not modeled) measurements from the Georgia Institute of Technology, mainly in 1981. This output takes into account sun angle, distance from sun, haze, clouds, and elevation.
• Ultraviolet Index is now also output, along with solar radiation, in a new output menu suite (#9). UV index is based largely on data from the Vantage Pro station at my school, but also from other sources, such as

  conditions: UV sensitivity to atmospheric

  radiation: Solar erythemal ultraviolet

  I developed the models for this and visible solar radiation largely myself, based on general theory and empirical fitting of the (SAMSON and Davis) data, but consulted the above sources for data and general understanding. The UV Index is, as best I can tell, basically in units of 25 mW per square meter, global, from about 280 to 390 nm, and closely fits the output of the Davis sensor.

• The above visible and UV outputs, along with a new total sky cover output, are now displayed on the Data Entry form in boxes whose values change with every adjustment of relevant factors (time, place date, clouds, haze, fog, etc.). This permits some forecasting of these items by simply 'playing' with the Entry form's controls, before making a forecast run. The ozone layer thickness in Dobson Units can be input here as well. A good source of real time data for this is

  Global Ozone Maps

• An extension of the 'weather' output text was made, so that sky condition (i.e. clouds) is always displayed (and printed, if you request a printout), even when dew, frost, fog, etc. are output. To accommodate this, the text window on the Output form was made wider. One small problem can result from this, however: the greater amount of data per line of output means the text box can fill a bit sooner than before. For example, you might find the text box filling up with just 6 days of half-hourly data, or three days with a 15 minute interval.
• You can now turn the 'convective bulletins on or off under 'Customize' on the menu bar. Turning it off may help you squeeze in all the output from a long forecast if you encounter the situation described in (7) above.
• Several related changes were made to wxrw1.exe (the retrieval module): Solar radiation handing was greatly improved, by using the new output from the main program and by re-calculating values from old forecasts. UV is likewise input and can now be calculated from old forecast data, except that the ozone layer thickness will then be assumed as 300 Dobson Units as a default. Up to 5 items (instead of 4) from each set of output options can now be displayed. Finally, the quality of the printouts was improved with bolder lines and text.
• The blue-text help files have been expanded to include the new items in the main program (wxsimw.exe), and to further describe old ones in the retrieval module (wxrw1.exe). For example, in wxrw1.exe you can now read descriptions or definitions of the various convective bulletins and stability indices.
• Now up to 11 columns of READY data can be read at once, to accommodate recent changes in the READY site. This allows 10 items, including wind flags (which use two columns) to be imported at once, making for - at most - two downloads to get all the data WXSIM can use (previously as many as three might be needed to get all readable data).
• Several changes have been made to the choices of 'Parameters' on the Entry form's menu bar. Output intervals of 2 and 3 hours have now been added, as well as new forecast durations of 5, 7, and 8 days. Along with this, the actual iteration interval (output interval divided by iterations per interval) is now forced to be 30 minutes or less, to help avoid the small errors that can creep in with larger intervals. Finally, this same 30 minute or less criterion is applied to export to .wxf files (for use in the retrieval module), to ensure saving of sufficient data for later analysis in that module.
• A new button on the Interrupt Planner opens up a form allowing you to specify timing and magnitude of partial, annular, or total solar eclipses. The eclipse will then occur automatically during the forecast run, with resulting changes in various conditions, especially temperature.
• The Text Width item under Customize now opens up a form with a scroll bar, allowing finer control of this item if text alignment is ever a problem.
• The retrieval module (wxrw1.exe) now automatically save a text file of the retreived data when you click 'View Text'. This file is saved under the name 'lastret.txt and into the same directory from which you retrieved the data (.wxf file). This new text file facilitates using the output in different ways, such as on a web page. Such posting of WXSIM output is permitted, as long as the program (WXSIM) and author (me) are credited. If you want to save images (screen shots) of graphical output, one way is to use ltPrtScrn and then paste into Paint or some other graphics software.
• Also in wxrw1.exe, the summary of overall data (i.e. averages, extremes) is now automatically printed below any printed plots, along with identification of the units used (which now also appear in the Text output).
• In the main program, a bug - which could occasionally cause the program to miss abrupt changes in planned wind direction or precipitation - was fixed.
• On the Interrupt Planner, the 'Showers' and 'Reduce superadiabatic' check box values, along with the wind direction tolerance, are saved for subsequent runs in the same session and for the next boot-up. The same has now been done for the feet/meters and Fahrenheit/Celsius buttons on the Upper Air form.
• A bug that caused the Interrupt Planner to forget the last-clicked values for precipitation and wind, when attempting to add more clicks (without clearing) on subsequent runs, has been corrected. Along with this, the shower option now uses the end of the forecast as the end of the shower period if precipitation is started but not altered (one click only). It operates as before in the much more common case of multiple precipitation changes.
• All six calculated stability indices (instead of just Lifted Index, as before) are now displayed on the Upper Air form.

Version 8.8.2 (September 5, 2003) had the following changes relative to Version 8.8.1 (described below):

• Recent changes in the headings of some data types on the READY site required corresponding changes in WXSIM's routine for reading these. WXSIM should now be able to read all the same data types as before, and still read older data as well.
• A bug on the Recent Precipitation form, which caused the last month's precipitation to default to a value in inches when metric units are in effect, has been corrected.

Version 8.8.1 (July 25, 2003) had the following changes relative to Version 8.8 (described below):

• Based on careful analysis of additional climatological/historical data, some changes were made to a routine handling moisture exchanges between the surface and the atmosphere and the surface (i.e. formation and evaporation of dew or frost). The main result, in most cases will be slightly more transfer than before, and hence slightly greater variations in dew point, mainly on clear nights and mornings.
• The 'Dew/Frost' scroll bar on the Data Entry form now allows somewhat greater amounts than before. The definitions of 'light', 'moderate', 'heavy', etc. have been changed slightly (i.e. what was called 'moderate-heavy' might now be called 'moderate'), but - for the sake of consistency - the numerical values shown will have exactly the same effects as before.
• Two changes were made concerning fog formation. First, the tendency to form fog was slightly reduced (in favor of more moisture consensing out as dew or frost). Second, this 'sensitivity' or proneness to fog formation can now be customized to the site. There may be multiple reasons, some perhaps difficult to identify, for site-to-site (or even time-to-time) variations in this, but such differences appear to be real. A recommended setting will be included with customization, but the user can now adjust it (under the 'Customize' menu item on the Data Entry form) if experience warrants. Any new setting of this is saved on program exit.
• Some changes were made to the help file, in light of the above changes affecting dew, frost , and fog.
• The METAR and synoptic surface data import routines were made more versatile, specifically to allow import of some New Zealand data fields which the program wasn't recognizing properly. In particular, the program now recognizes kilometers as a valid visibility unit (previously, only statute miles and meters were recognized) in METAR data, and now recognizes whole number temperatures and dew points in synoptic data, in addition to the standard one-decimal place format.
• Slight changes were made to the registration information, mainly to alert new users to check web sites for a possible new pricing structure in the fairly near future.

Version 8.8 (July 15, 2003) had the following changes relative to Version 8.7.2 (described below):

• Under Start on the Entry form there is a new option: Full Start. This combines the actions of Test for Midpoints and Calibration Run, to save a mouse click. The earlier items are still there and can be used as before; there are times when the midpoint times are of intrinsic interest, or when one might want to alter the initialization time (and corresponding data) in order to change which of the two daily midpoints starts the calibration run (this being a somewhat 'advanced' manipulation, however).
• The output is now saved by default, rather than requiring previous approval. The default file names are 'latest.wxf and 'latest.txt, but other names can be specified in advance under the File/Save item, where it is also possible to avoid saving data if desired.
• The choices (check boxes) of data import types on the Import form are now 'remembered' during the run and saved upon exit, thus saving most users a few mouse clicks each run.
• The check boxes on the FOUS form are now checked by default, except for the shower option, which can still be checked if desired (it is overruled by the shower check box on the Interrupt Planner if precipitation is entered there).
• A bug has been corrected. The problem was a bad interpolation between level 1 and 2 for finding the height of the 925 mb level, when the surface pressure is above 925 mb, which is usually the case for sites below about 750 meters (2500 feet) elevation. Actually, the error was negligible with surface pressures in the range of 960-1000 mb, but often significant above and below that. In most cases this error probably had no effect other than the erroneous output on the upper air data form.
• Improvements were made other interpolation algorithms for 925, 850, and 700 mb heights and temperatures, mainly for stations at relatively high elevations.
• Heights and thicknesses are now geopotential (as opposed to geometric), with respect to the surface. The previous algorithms (from a few years ago) were slightly flawed due to an attempt to make the heights geometric (geopotential is actually more the standard) and then fit them to radiosonde data, which turned out to be geopotential. The previous errors, relative to geopotential values, were negligible in the mid latitudes, except possibly at 300 mb, but were marginally significant at low and high latitudes (within perhaps 30 degrees of the equator or of the poles). The present scheme provides very accurate geoptential values.
• A new customization parameter was introduced in order to better fit climatological normal temperatures, with dew points also "piggy-backed" into the scheme. The fit was already excellent in most cases, but for some sites - especially in the western United States - small discrepancies remained because of a more rapid cool-off in the fall as compared to the spring warm-up. The new parameter now gives an excellent fir for these sites as well. It is doubtful that any sites already customized suffered more than about half a degree F error because of the earlier inadequacy (and that mainly just in the spring or fall).
• It was found that, in the 'Other' location option (as opposed to custom sites), entered climatological normals would revert to default values after one run, with no warning. This has been changed to preserve the user-entered values through multiple runs, and also to re-prompt for new data if the date is changed while the 'Other' option is still in effect.
• The manual was expanded to include detailed instructions on collecting data from the Internet and examples and explanations of such data.
• A new form, with a message for new users, was added. Further viewings can be prevented by leaving a check in the 'Don't show this message again' box.
• The program's starting form now sports a graphic: a photograph taken by the author in July, 2002, from the top of Mt. Tamalpais near San Francisco. The view shows sunset over a deck of stratus in the the marine layer inversion over the cold waters of the Pacific. Temperatures at the time were about 10 degrees F warmer atop the 2500 foot mountain that at sea level! If you don't want to see the picture on startup, or if you want to make the space (901 KB) available, you can delete it without affecting the program.

Version 8.7.2 (June 14, 2003) had the following changes relative to Version 8.7.1 (described below):

• A bug in the retieval module (wxrw1.exe), that labeled every day 'Monday' when retrieving data stored in day/month/year format, was corrected.
• Provisions were made to avoid possible problems involving the use of commas (i.e. as done in many European countries) versus periods as the decimal point symbol. It was not clearly established that any errors were beings produced this way, but the change was made to help preclude the possibility.
• A problem was discovered involving the interaction of the program with some Windows environments. In particular, Windows 2000 under Dutch settings and Windows XP under U.S. settings, were found in sporadic cases to misread READY wind direction data, sometimes causing errors (Invalid Property Value, Overflow, or simply making the wind direction north when it wasn't). A work-around was implemented (it wasn't a 'bug' in WXSIM, per se) and the problem is now apparently corrected.

Version 8.7.1 (March 9, 2003) had the following changes relative to Version 8.6 (described below):

• A bug that could very occasionally read METAR data as MAPS soundings was corrected.
• In the retrieval program, saving of settings upon exit now includes the new 850-700 mb thickness and freezing level options.
• The precipitation type algorithm was modified to take into account more details of the vertical temperature profile. Numerous schemes for precipitation-type decisions were reviewed and an effort was made to make WXSIM's decisions closer to the consensus of these others. Results will be very similar to before, but with some rain and sleet mixture situations now replaced by rain and snow mixtures. Also, sleet occuring in dry surface conditions will more readily turn to rain in certain situations as the air approaches saturation.
• Some new precipitation descriptions were added, including distinguishing between primarily rain mixed with some snow (RN/SNW) and primarily snow mixed with some rain (SNW/RN).
• The algorithm for determining upper boundary layer temperatures was found to yield too-warm values in many precipitation scenarios. This was corrected to make more likely lapse rates in the boundary layer during precipitation.
• 850-700 mb thickness (often useful in distinguishing between rain and snow) was added as an output on both the Upper Air form and in the text output. It is also included when saving data, for later recall with File/Retrieve.
• Freezing level (above both sea level and ground level) was added as an output on both the Upper Air form and in the text output. It is also included when saving data, for later recall with File/Retrieve.
• The Retrieval module was modified to include 850-700 mb thickness and freezing level.
• Changes and additions to the help file were made in light of the above changes.
• The map file was augmented to include all of South America.

Version 8.6 was (January 29, 2003) had the following changes relative to Version 8.5 (described below):

• Routines involving mixing in the lower atmosphere were modified to allow greater surface warming than before under certain conditions (conducive to mixing) involving warm air in levels 1 and 2. Similarly, more mixing (than before) with cool air in levels 1 and 2 is now allowed, keeping temperatures closer to WXSIM's thickness-based maximum temperature estimate.
• Three new features were added to the advection options. First, a best fit straight line fit was added to the existing options. Second, data points are now plotted along with the curves on the upwind gradient graph. Finally, a new 'distance ratio' adjustment option was added to the Regional Data routine. Previously, data from stations varying in upwind distance by a factor of less than 1.3:1 were averaged together. The default is now 1.15:1, which is generally better due to the large number of advection sites now included in most customizations, and also allows finer resolution of changes in the slope. This factor can now be adjusted from 1:1 (no averaging) to 1.3:1 (the old value).
• New help items were added for the above features.
• User-made changes in the Interrupt Planner's wind direction change tolerance (default is still 40 degrees) are now saved until (but not after) exiting the program, allowing for slightly quicker repeat forecast runs.
• Changes were made to accommodate the new READY meteogram text format (the old data can still be read, in case you want to run old files). Small changes were also needed even for the supposedly 'old' format available until February 1, 2003, as there were actually some small labeling changes even there. There is now no need to remove headings, and mixing of model data can still be done, by simply listing the multiple models in the same file.
• A major new addition is the ability to read NGM, AVN, and/or ETA MOS data for advection sites, simply by selecting the 'MOS' option and importing from the appropriate file. This is generally not advisable at program initialization, but can be a big help later in the forecast run if wind shifts occur. WXSIM will read the MOS files for each site (they can be listed in any order), interpolating between 3-hourly reports and averaging (successively weighting average so far equally with new values) if multiple MOS products are found for the same site.
• A change was made in the reading of '6 hour' precipitation totals in 3-hour output READY data (such as AVN short range). I had assumed previously that the values listed in the file were actually 6 hour totals, but I've been informed by Glenn Rolph (the site's webmaster) that the figures are derived by subtraction of successive 3-hourly data, so that, in effect, they are 3 hourly totals. This means that, until now, WXSIM's precipitation totals - when derived from 3-hourly AVN data - were only about half of what they should have been (perhaps more like 3/4 if FOUS products were used in the run as well). Now WXSIM should mirror the AVN totals listed on READY's meteogram graphic (unless FOUS data is mixed in). The AVN datasets are being renamed GFS, but they should be read by WXSIM in the same way as the AVN.

Version 8.5 (December 27, 2002) had the following changes relative to Version 8.4.2 (described below):

• Maps of coastlines, lakes, and political boundaries now appear with the regional data advection routine. Also, the number of different METAR or synoptic stations for which data is found now appears at the bottom of the map when surface data is imported.
• The ability to zoom in and out on the regional data advection map is now triggered by simply changing the gradient plot scale ('+' and '-' buttons on the lower right of the frame). Also, a new, closer scale (out to just 300 miles or 500 km) is now available.
• A new 'Search' button in the Cyclonic/Anticyclonic flow section of the Advection form triggers an automated search for the best fit to curved flow. It first varies the curvature to maximize the 'percent' fit (of station wind directions to the modeled flow), then re-imports data in case this change brings new stations into 'view'. After varying curvature to optimize the fit again, it goes through the process one more time in an attempt to further optimize the fit. The two additional imports do not trigger loading of the Import form, sparing the user additional mouse-clicks.
• The help files were ammended to explain the 'Search' feature described above.
• Message boxes now appear to advise the user if no imported advection data exists when the Search, Use All, or Ignore buttons are clicked.
• The Default (frontal codes) advection routine was changed to more accurately calculate longitudes and latitudes of upwind points. The previous routine, which had some inaccuracies in certain directions and didn't operate well near the poles, was replaced with a great-circle routine (new equations adapted mainly from Ed Williams' Aviation Formulary
• Small improvements were made in the effects ground moisture, more properly including the effects of rain in the last month as well as the last week and last day. The changes show up in the Estimated Max temperature (on the Upper Air form) as well as in the forecast run, but rarely amount to more than about one degree F (0.6 degrees C) compared to Version 8.4.2. The changes were based on new studies of 1961-1990 data from stations in the southeast U.S. as well as an ongoing verification study in Atlanta.
• A bug which could cause an error during 24-hour darkness or light in the arctic or antarctic was fixed. This bug may have surfaced in recent editions, because the issue had been addressed before.
• A bug that sometimes caused misreporting of AM lows was fixed. This bug occured very rarely, when certain combinations of starting time, output interval, and iterations per interval were used.
• A bug that prevented proper updating of the relative humidity and wet bulb entries (on the Data Entry form) upon import of METAR data, when Celsius degrees were in use, was fixed. The bug did not actually affect the program's output, but only the display.
• A bug which failed to adjust imported METAR sea level pressures and altimeter readings to station altitude, when the station pressure option was on, was fixed. There was no problem if sea level pressure was selected, but if import was done while station pressure was selected, significant output errors could result (at least for stations significantly above sea level). Now the adjustment is made as needed. Incidentally, synoptic reports were properly read anyway, since both station and sea level pressure are routinely reported; here WXSIM simply uses the one whose option is selected.
• A decimal place was added to the imported millibar (hectopascal) pressure diplay on the Entry form, so that tenths are now displayed.
• Displays of vapor pressure and mixing ratio were added to the temperature and humidity section of the Data Entry form, and small cosmetic changes were made to the form to help the new items fit. These new items are simply displays, and are not currently direct inputs or outputs of the program.
• A small bug which occasionally prevented display of the first regional data advection site on the map was fixed.

Version 8.4.2 (May 31, 2002) had the following changes relative to Version 8.4.1 (described below):

• A bug that prevented complete culling of synoptic and METAR files in some cases (for recent, large customizations) was corrected.
• A change was made to enable import of a certain (European, primarily?) RAOB format that had been rendered unreadable by a recent change on FSU's interactive text web page.
• A small change to the retrieval program (wxrw1.exe) now saves the user's choice of North American or Northwest European stability indices upon exit.

Version 8.4.1 (May 4, 2002) had the following changes relative to Version 8.2.9 (described below):

• WXSIM can now read NGM and ETA FOUS data from FSU's newly (May 3) reorganized web page, which presents the data with leading spaces not present before. WXSIM can still read any format that it could before. The new FSU page is here
• A bug, which caused an error when modifying forecast (.wxf) files saved to a floppy disk, was corrected in the retireval program (wxrw1.exe).
• The effect of the 'Reduce superadiabatic' option on the planner was reduced by a bit less than 40%. Its effect is now quite small in most cases, but it is still recommended, and is checked by default.
• A message box that appeared upon attempted changes to preciptiation on the interrupt planner, when cloud cover was insufficient, has been omitted. This change allows easy removal of READY model-based precipitation that the user deems unrealistic.
• Precipitation now makes less difference in solar radiation reaching the ground than before. This allows at least light precipitation with partial sunshine.
• The high temperature routine now assumes more random fluctuation than before with broken to overcast cloud cover, adding about a degree F to highs in many such cases. This routine is calibrated on the assumption that input or imported (from external model data) cloud cover changes have a time resolution of about 3-6 hours.
• The retrieval program was modified to use the new high temperature routine. This required use of the haze variable, so modifications were made to both wxrw1.exe and wxsimw.exe to include this data in .wxf files. The new wxrw1.exe can still read old .wxf files.
• A bug that caused the main program (wxsimw.exe) to assign 12:00 AM to the previous day's date was fixed.
• The text box in the Import form showing the number of METAR sites found was expanded to accommodate 3 digit numbers.
• In the retrieval program (wxrw1.exe), a bug that (rarely) caused a one day shift of the date, day of week, and low and high temperatures relative to the plots was fixed. Also, occasional displays of these items for days with no data were eliminated.
• A few internal changes were made in both programs: code was moved between modules in wxsimw.exe to avoid memory problems during compiling, and some unused code in wxrw1.exe was removed to reduce file size.
• A choice of text and graphical output background colors (blue or gray) was added. It can be found under the menu item 'Customize' on he Data Entry form.
• Day of the week was added to most graphical and text output items, both in the main program and in the retrieval module.
• Various small cosmetic changes were made in both the main and retieval programs, including printouts.
• A bug in the new Mountain/Valley breeze routine was corrected (uphill and downhill had been switched).
• The user can now change diurnal breeze base wind directions on the advection form, though this is generally not necessary. An addition to the base wind message box now alerts the user to this possibility.
• A feature was added enabling customization of the amount of nighttime fluctuation in temperatures, to better deduce minimum temperatures from the regular output. Also, the retrieval program was modified slightly to accept this parameter from the main program.
• A new Mountain/Valley Breeze routine was added. It and the Sea Breeze routine are now options (mutually exclusive) under the new refinement item 'Diurnal Breeze'. New blue-text halp features describe these options.
• Diurnal breezes (above) are allowed to operate even with planned wind speed and direction, with the planned changes acting on the base (no diurnal component) wind.
• Changing date or location with sea breeze in effect now cancels the routine, so that updated water temperatures can be verified or input before reactivating it.

Version 8.2.9 was completed on March 3, 2002 and had the following changes relative to Version 8.2.6 (described below):

• A change was made to improve operation of the 'Reduce superadiabatic' option when FOUS data is also in use.
• A bug in the regional advection routine was corrected. This started with a misnamed variable in Version 8.2.4 and caused fairly small, but sometimes significant errors in the adjustment of data for advection sites. It tended, in general, to reduce the effectiveness of both cold and warm air advection.
• Fairly small adjustments, motivated by testing on both recent and historical data, were made involving the handling of unseasonably cold air. In particular, the diurnal temperature range in cold air masses was increased slightly, and the rate of air mass modification (in this case, warming) was made more dependent on the depth of the cold air mass; deeper cold air now modifies more slowly relative to shallow cold air than before (though shallow cold air may now modify more quickly than in earlier versions).

Version 8.2.6 was completed on February 24, 2002 and had the following changes relative to Version 8.2.5:

• 900 or 950 mb relative humidities can now be imported from READY as a substitute for 925 mb, which is not available in some models (i.e. ETA 91 km).
• A message box now appears after READY import if multiple models were found and mixed. It also tells which items were averaged.
• A bug, which sometimes made the import form look for home site data when it should be seeking advection data, was corrected. This bug had occured if multiple attempts to access the import form were made from the advection form.
• A shower toggle interrupt item was added. Pressing 'p' (or accessing Interrupts/Precipitation/Toggle Showers) during the forecast run toggles the FOUS and/or Interrupt Planner shower option on and off.
• The following changes were made to the Retrieval program: Up to 10 days of data can be retrieved, and the last choice of skew versus rectangular detailed sounding plots is saved on exit.

Version 8.2.5 was (February 18, 2002) had the following changes relative to Version 8.2.4:

• READY data import now allows multiple models, such as AVN 111 km and ETA 40 km to be imported at the same time, with any repeated items being averaged. The data must have the same time interval (i.e. 3 hours).
• 1000 mb winds (i.e. from the MRF model) may now be imported from READY. The wind speed is adjusted to make it more representative of 10 meter winds.
• READY relative humidities are now used to determine clouds even without Total Cloud Cover being imported.
• Optionally (using a check box on the Interrupt Planner), 850 mb temperatures on the planner can be partially overridden in the case of super-adiabatic lapse rates. This allows WXSIM more 'say' in surface temperatures when external model data is producing 850 mb (or 700 mb for sites above 2500 feet) temperatures that would otherwise drive them down.
• Four new help topics were added to the Interrupt Planner form.
• Three bugs were fixed: part of a low level mixing routine was found to be time-interval dependent, and was made independent of it. An error that occured if location was switched while Sea Breeze was active was fixed, by deactivating Sea Breeze upon location change. Also, an error that occured if Snow Cover was activated - but no snow entered - was fixed.

Version 8.2.4, finalized January 20, 2002, has the following changes relative to Version 8.1 (described below):

• Under rare circumstances, earlier versions could have an Invalid Property Value error during the calibration run if heavy precipitation was entered on the Recent Precip form, ending some time shortly after the last midpoint. This has been corrected.
• All data import check boxes other than surface data are now disabled when accessing the Import form from the Advection form. This prevents certain errors that could occur if model or upper air data were brought in at this (late) point. These items should be entered before the calibration run.
• Changes have been made in the handling of snow, specifically: the albedo algorithm has been changed to include the effects of dark ground cover (part of the customization), the rate of compression/settling of deep snow has been increased, effective insultation from the ground has been made a function of snow/water ratio (fluffy snow insulates better), the melting rate has been made more dependent on ground temperature (especially via the 'last 4 days' user input), and freezing rain now accumulates at a much reduced rate on top of snow, greatly decreasing the average snow/water ratio of the snow/ice pack.
• Some display-related bugs involving the fog, haze, and current precipitation inputs have been fixed: using 'Repeat' now completely reverts these and the visibility to the previously entered values and the visibility now properly reverts to 50 miles if fog is set back to zero with no other visibility restrictions (it was getting stuck at 40).
• A message box now warns of certain READY import problems (resulting mainly from inappropriate spaces in the data) instead of the program locking up while trying to read it.
• Internal changes were made to reduce memory requirements. A beneficial side effect is that the water temperature used with the sea breeze routine now updates readily with date or location changes (it used to require turning off and back on to erase the old temperature).
• The ability to model curved (cyclonic or anticyclonic) flow has been added to the Regional Data advection routine. The goodness of the fit to winds at upwind sites is reported so that the user can adjust the flow to more closely match that indicated by surface reports.
• A text file of program output is automatically generated and saved whenever a forecast (as a .wxf file) is saved. The full forecast is saved (no '60 hour' option anymore).
• To allow the user to better characterize soil moisture, the 'recent Precip' form has been modified to allow input of the rainfall in the last month (in addition to the last 24 hours and the last week, as was already provided). The effect is that greater extremes of soil moisture (i.e. very dry with resulting large diurnal temperature range and tendency toward lower dew points) can be modeled. Also, small changes in the soil moisture description output were made to take into account to some extent the site's normal annual precipitation; for instance, 'very dry' for a usually moist site might be only 'fairly dry' for a normally dry location.
• A subtle but in some cases significant change was made to an air mass modification rate parameter. In particular, it was found (using mainly 25 years of hourly data for Atlanta, Georgia and Peoria, Illinois) that WXSIM was tending to modify air masses (warm up cold spells and cool off warm spells) too quickly, mainly in the fall and the spring. The existing error was smaller in summer and very small in winter, so the applied correction is seasonally and somewhat site-dependent.
• Small changes were made to the routines for estimating maximum and minimum temperatures based on the modeled temperature output. The main change involves low temperatures in clear conditions with light winds. A study of minimum temperatures relative to lowest reported hourly values and to temperatures at the usually coldest hour (i.e. 7 AM in many cases) showed that most stations have short term (in between hours) fluctuations of about 1 degree Fahrenheit in such cases - more than what WXSIM had previously assumed. Also, it was found that winter clear day fluctuations near the time of afternoon maximum temperature are a bit smaller than previously assumed. The changes were made to best model the latest data.
• A very slight increase in downward infrared radiation was incorporated, mainly to offset some the the effects of the changes described above, but it might also be considered to represent a small amount of 'global warming'. The change is only a few tenths of a degree F.
• The dimensioning of several arrays associated with advection was increased so that WXSIM can now handle up to 48 (previously 28) upwind sites near a particular direction and a total of 300 (previously 175) overall advection sites. This allows room for the extra sites that may 'come into view' when using the new curved flow option and also allows for somewhat larger advection site databases in future customizations.
• The dimensioning of some arrays associated with the Interrupt Planner and READY meteogram import was increased so that 35 (previously 25) data points can handled for each variable. This allows import of the full 84 hours of 3-hourly 40 km ETA data now avalable on the READY site (only 60 were available until recently). This change also allows more manual clicks on the Planner.
• A METAR import bug was found: WXSIM to misinterpret a certain field of digits mixed with slashes as a temperature and a dew point. This seems to be rare and present only in certain European METARS, but the bug is now corrected.
• The U.S. National Weather Service recently released a new wind chill algorithm for official use. It is generally more 'conservative' (not as cold) as the old one. WXSIM now uses this new version.
• The changes in WXSIM's extreme temperatures and wind chill are also now incorporated into the Data Retieval module. To enable the new low temperature algorithm in the retrieval program, a slight change was made in the format of the saved .wxf files (they now include a temperature inversion parameter). The new program can still read the older formats, as well as the new one.

Version 8.1 (July 3, 2001), had the following changes relative to Version 7.3 (described below):

• The algorithm for finding lifted and Showalter indices was improved. The new values are generally a bit more negative than before, the difference being close to 3 for LI and 1 or 2 for Showalter.
• Adjustments to the convective outlooks were made, based partly on the above changes and also some re-weighting of the indices for the Northwest European outlooks (Boyden and KO were given more weight).
• A new feature was added to the upper air sounding graphs on both the main program (wxsimw.exe) and the retrieval module (wxrw1.exe): lifted parcel traces from the surface (yellow) and level 2 (green). These include both dry and saturated adiabatic effects and provide a visualization of stability. The temperature and dew point lines were also made more bold for easier viewing.
• The slant of the skew-T graph in wxrw1.exe was made more standard.
• A new (fifth) advection option, which allows direct clicking of upwind temperature and dew point profiles onto the graph.
• A new 'Ignore' button, allowing the user to weed out suspect data by highlighting the site in the regional data list box and clicking the button, which also executes the 'Use All' function automatically.
• Level 1 and level 4 clouds are now phased out of READY data (unless you click them back in) on the Interrupt Planner, to allow more accurate overall cloud cover based on the model data in levels 2, 3, and 5. A similar effect is now also available for NGM and ETA FOUS, by checking the appropriate box on the FOUS usage setup form.
• The Interrupt Planner's Shower option now produces rain of 5 times the intensity for 1/5 of the time (instead of 3 times, 1/3 of the time), to allow more accurate overall cloud cover in shower situations. A bug which caused excessive rainfall when this was combined with FOUS data was also corrected.
• Handling of upper air temperatures, when using 850 mb temperature and 1000-500 mb thickness on the Interrupt Planner, was improved. (Previously it had sometimes concentrated the adjustments too much in level 4; level 3 now adjusts as well to produce a smoother sounding profile).
• A new output menu option (#7) has been added, including sea level pressure and three new stability index outputs: K, Total Totals, and Showalter (which was also added to the RAOB data form).
• Convective bulletins, giving a text description of the likelihood of showers and thunderstorms, including their likely severity, have been added to the text output. These appear as conditions change.
• Import of 850 mb (700 mb for sites above 2500 feet) relative humidity from the READY site is now supported. This helps with the new stability indices (above).
• The 850 mb (700 mb for sites above 2500 feet) relative humidity data and/or (depending on which options are in use) FOUS humidities are now used in determining the level 2 dew point. This may have small effects on surface temeprature and dew point, especially in clear weather.
• Improvements were made in the FOUS-based cloud algorithm.
• A shower option was added to the FOUS setup form, and interaction between FOUS and READY precipitation routines was improved to produce precipitation amounts near the average of the two when both are in use, even with the READY shower routine in effect.
• Two bugs were corrected: Variable wind directions in synoptic reports are now imported properly. Also, there had been an incorrect message stating that data (FOUS, RAOB, or READY) was over 24 hours old in the case of 00Z data from the first day of a month used in the evening of the last day of the previous month (and this only for west longitude time zones). This bug was corrected as well.
• There were more adaptations to changing READY data formats (see below).

Version 7.3, finalized April 12, 2001, includes one change from Version 7.2.9, in response to a small change in the format of READY meteogram data: the year is now four digits instead of two. Version 7.3 properly reads the new format as well as the older ones.

Version 7.2.9 (April 3, 2001) included three changes from Version 7.2.8:

• An inappropriate 'stop' command that was executed when retrieving saved interrupt planner files was omitted.
• Two changes were made to permit use in Italian (and perhaps some other) regional Windows settings: dot (in addition to colon) time separators are now allowed, and some default text box content that caused a crash - due to conflict involving decimal points versus commas - was changed to avoid such problems.
• A new parameter was added to help model large seasonal changes in vegetation effects for future customizations. (This has no effect on previous customizations.)

Version 7.2.8 (finalized March 17, 2001) corrected a problem which allowed the duration of READY data to interfere with that of FOUS data. Version 7.2.7 (March 17, 2001) allowed for import of new, slightly differently formatted (in the date/time section - already corrected in version 7.2.6 - and now also in the forecast hour line) READY meteogram data, though it can still import the older formats, too. Version 7.2.5 (January 25, 2001) added the option of dots as date separators, as used in some parts of Europe. Also, an oversight, which had allowed the chosen time interval to influence the effect of the (optional) Recent Temperatures/Last 4 Days input, was corrected. Version 7.2.3 (January 11, 2001) corrected a rarely encountered division by zero error that happened when importing READY meteogram data if the V component of wind was exactly 0.00. Version 7.2.2 (January 9, 2001) improved handling of the effect of nearby moderate-sized bodies of water for certain sites. Version 7.2.1 (December 31, 2000) corrected a minor RAOB import bug in Version 7.2 that had caused erroneous 1000 mb heights when that height was below sea level.

Version 7.2, finalized December 27, 2000, contained significant new features and changes:

• An option was added to import a variety a model (especially AVN and ETA) meteogram data from NOAA's READY site and place it on the Interrupt Planner for possible use in the program. This is especially significant because it now allows import and use of model data (mainly AVN) worldwide (not just North America).
• Handling of advection over upwind mountains was improved by taking into account the effects of condensation on the windward side, which may reduce dew point and raise temperature.
• 850 mb (or 700 mb for sites above 2500 feet) temperature was added to the Interrupt Planner, and its scale adjusts along with 1000-500 mb thickness's scale (see #1 below).
• Several minor adjustments and additions were made, involving higher altitude sites. These include better reading of RAOB and SYNOP data, and and adjustment to the interrupt planner's thickness' diurnal range.
• ETA and NGM FOUS data can now be averaged in with data (including that from the READY site) on the Interrupt Planner, and because of this, no planner items are disabled.
• Preciptation on the Interrupt Planner can now be specified to occur in showers, of 3 times the intensity and 1/3 the duration of the continuous rain otherwise planned.
• Small changes were made to avoid errors due to certain non-U.S. Windows settings. These include recognition during boot-up of year-first date formats and a font and command change in the on-file site list box.

Version 7.1.3, finalized November 5, 2000, contained the following changes from 7.1:

• The option of different scales for 1000-500 mb thickness on the Interrupt Planner was added.
• A bug - which improperly intialized the interrupt planner's thickness after advection data import with FOUS having also been imported - was corrected.
• Import of yet another variation on TTAA RAOB data was enabled.
• A bug which had allowed the 'Start Fresh' option to shut down the program was corrected.
• Rewording was done to permit free distribution of this manual.

Version 7.1.2 was finalized on September 16, 2000, enabling use of another format of TTAA data, in which all lines after the first are indented. Also, a bug which caused inaccurate initialization of 1000-500 mb thickness on the interrupt planner (only when FOUS and advection METAR were both imported) was corrected.

Version 7.1.1 was finalized on September 11, 2000, correcting a bug that caused the program to shut down when using the 'Start Fresh' option. The only changes from 7.0 to 7.1 were two bug corrections: a problem with RAOB import when using French Regional Windows settings was corrected, and a text alignment problem when using a certain graphics mode was corrected by expanding the text width options.

Version 7.0 was finalized on August 18, 2000, and included the following improvements over Version 6.4:

• A form with a clickable graph for planning changes in cloud cover, wind, pressure, precipitation, and thickness was added, greatly reducing the need for interrupting the program as it runs. This includes the ability to save plans to file for later use.
• Some improvements in the 'Other' (not on file) site routine, though customization remains essential for accurate forecasts.
• Various minor changes, such as wording, certain default choices, and the addition of sea level pressure (as preferred over altimeter setting) in METAR import.
• Revisions and improvements to the retrieval program (WXRW1.EXE), including minor bug corrections, the addition of a comments section, and saving of settings on exit.
• The ability to import synoptic data (in addition to METAR) was added.
• A new upper air adjustment button (called '1-Click') was added. This automatically determines how recent the RAOB and/or ETA/NGM FOUS data is and adjusts WXSIM's upper air profile accordingly - including a diurnal adjustment for RAOB data.
• The FOUS and RAOB buttons, as well as the new '1-Click' button described above, now adjust level 1 and 2 dew points as well as temperatures.
• The 'Use Previous' functions on the Upper Air and Advection forms were modified to make them complete in recalling all previous data, whereas before, a small amount of information had been lost (namely, the 'fixed' dew points for upper air, and the 'monotone' option for advection).
• ETA or NGM FOUS data is now recognized at times other than 00Z or 12Z (as ETA has recently begun generating output at 06Z and 18Z as well) and is mixed with any older data appropriately (including a new default ETA/NGM weighting factor).
• The standard of using commas for decimal points (in certain European countries) is now supported, if Windows is set accordingly.
  

Version 6.4 was finalized on February 19, 2000, and included the following improvements over Version 6.0:

• The ability to use NGM and ETA FOUS data for relative humidity (to model changes in cloud cover), wind, and precipitation was added.
  
• Synchronization between ETA and NGM FOUS data 12 hours apart is now more properly done.
  
• The program now uses a mean boundary layer wind direction estimate in combination with the actual surface wind for advection and other purposes. (This is usually different from before by less than 15 degrees).
  
• The advection site data plotting routine includes an output consisting of a weighted average wind velocity for the advection sites along with the home site, to give a better picture of the overall wind flow and permit appropriate adjustments to wind direction if desired.
  
• The effect of snow cover on temperature was studied in greater depth than before, using 25 years of data for Peoria, IL and Nashville, TN, and eight years of data for Flagstaff, AZ. In light of this new data, the cooling effect was reduced by about 20-30% relative to before.
  
• The effect of recent rainfall on subsequent diurnal temperature ranges was studied in greater detail than before, using 20 years of data for Atlanta, GA. As a result, improvements were made in WXSIM's algorithms, including correction of a minor bug.
  
• The above results were also incorporated into the low-level-thickness derived Estimated Maximum Temperature.
  
• Descriptive terms for precipitation intensity were brought into close agreement with those outlined in the Federal Meteorological Handbook #1.
• The visibility algorithm was modified in light of further research, particularly regarding restrictions due to various types and intensities of of precipitation. In addition, a message box was added to warn the user when the visibility reported in a METAR for the home site is 10SM or 9999, which are often defaults used (such as with automated observing equipment) when the visibility is actually greater.
• Estimated Maximum Temperature and Visibility were added as output variables, in output menu formats 2 and 3, respectively.
• An option called '~Monotone' (approximately monotone) was added to the smooth curve advection data fit. If checked (as it - in effect - was in version 6.0), a very distant data point with climatological normals is included, causing the upwind gradient curves to be either constantly increasing or constantly decreasing in most cases. If not checked, advection may change sign from warm to cold (i.e. a cold frontal passage preceded by warming) or vice versa.
• A couple of minor bugs were fixed.

Version 6.0 included several advancements made since the release of V5.4 about a year ago, as follows:

• Upwind advection sites and (if data was imported) simple station model plots for these sites are now plotted to help you visualize the sources of the advection data.
  
• There is now an option for smooth, least-squares regression fits for advection data, regardless of the number of sites chosen.
  
• There is now an option to select and use all imported METAR and buoy data with a single mouse-click.
• Certain types of ocean buoy data (namely, the format used on Penn State's web page) can now be imported and used.
• A new 'status' bar at the bottom of the data output form keeps the user informed as to whether or not various features (i.e. advection, FOUS, sea breeze, auto cumulus, etc.) are currently active.

Between Version 4.0 and 5.4, a MAJOR data collection and program calibration effort was undertaken. This involved many years' (up to 30 in one case) worth of hourly surface data from several stations, correlated with upper air data using a program written especially for this purpose. (The data sources were the National Climatic Data Center's SAMSON CDROM and North American Upper Air Data 1946-1996 CDROM. I wrote the extraction and analysis program).

V5.4 included many improvements made since the release of V4.0 about two years ago, as follows:

• A new low-level-thickness-based maximum temperature routine
  
• Additions to the help files and the user's guide
  
• Improved handling of slowing of cold air advection by mountains
  
• Maximum daily temperatures at high latitudes in winter, especially with snow cover, were found to be occuring too early in the afternoon. This has been corrected to fit recent data analysis.
• Increased versatility has been added to the customization process to better fit the diurnal temperature curve for arid sites and to better model diurnal wind variations at specific sites.
• The data import feature has been modified slightly to eliminate confusion between METAR and other types of data having station ID in the same field.
• More thorough screening is now available for 'weeding out' in-between-hours METAR reports if desired.
• A bug that sometimes inappropriately deactivated the low stratus routine was corrected, and associated default upper level dew point routines were refined slightly.
• Improved upper air temperature routines
  
• Improved initialization of boundary layer temperatures
  
• Ability to re-generate advection data and upper air adjustments from previous run
  
• Quick new method of driving initial upper air temperatures towards FOUS or RAOB values
  
• Ability to read RUC-2 analysis soundings
  
• Ability to cull through large files to extract relevant data and create smaller, more appropriate files
  
• Much improved ability to import data from web pages with no copying or pasting needed.