New Features and Revision History

This section should be very instructive even if 11.8.7 is the first version you've used.

Version 11.8.7 was completed on June 27, 2008 and has 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 http://www.emc.ncep.noaa.gov/gmb/STATS/STATS.html.
• 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.

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

• 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.

• 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.')

• 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).

• 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 http://facstaff.uww.edu/travisd/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).

• 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.

• 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).

• 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 http://moe.met.fsu.edu/buoydata/data/.
• 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.

• 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.

• 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

  UV sensitivity to atmospheric conditions: http://sedac.ciesin.org/ozone/rtm/uvsens.html

  Solar erythemal ultraviolet radiation: http://www.iac.ethz.ch/en/research/chemie/tpeter/www_uv.html

  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: http://woudc.ec.gc.ca/e/ozone/Curr_allmap_g.htm

• 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.

• 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.

• 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.

• 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 at http://williams.best.vwh.net/ftp/avsig/gcircle.pdf).
• 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.

• 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.

• 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 at http://www.met.fsu.edu/weather/text_weather.
• 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.

• 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).

• 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.

• 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.

• 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 7.2.9 (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, 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.

• 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.
  

• 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.

• 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.

• 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.