New Features and Revision History
This section should be very instructive even if Version 2017, Build 1.0 is
the first version you've used.
Version 2017 (Build 1.0, completed February 18, 2017) has the following changes
relative to Version 2016, Build 1.2 (described below):
(1) Added the ability to customize shadowing by mountains, and effects of sloped
terrain in general (on solar radiation)
(2) Fixed a bug which on rare occasions caused the date to revert to the start
date during the forecast (I think only one user ever reported this, but I was
able to reproduce and fix the problem)
(3) Added an option (under Start/Auto run and Other Settings) to omit humidity
(dew point) bias and WXSIM-Lite corrections, which keeping all the temeprature
stuff. This was mainly motivated by one user whose station's hygrometer totally
failed, but I've seen other questionable humidity data in users' files before,
so this may have some wider application.
(4) Created WRETMATE, a companion program (openable either alone or via buttons
in wret.exe, autolearn.exe, or wxsimlite.exe) which allows you to easily manage
the large number of old forecast (.wxf) files which can acculate over time and
potentially make WXSIM-Lite or WRET/Autolearn rather slow in completing their
analyses for bias corrections ("learning"). This new program allows
you to (reversibly quarantine archived forecasts that are too old or have non-standard
names. It also lets you randomly cull the list of forecasts down by a percentage
of your choice (i.e. if you were making forecasts every hour, you could trim
the analysis set down to, say, an average of 5 per day, for quicker processing).
(Note: Version 2016, Build 1.3 was experimental and not officially distributed).
Version 2016 (Build 1.2, June 15, 2016) had the following changes relative
to Version 2016, Build 1.1 (described below):
- A new bug (a division by zero error) had resulted from fix #3 in Build 1.1
(below), for users having selected the (mostly used in Canada) humidex option.
This has now been fixed.
- Protection was added against older version's customized files producing
an invalid property value error in the GFS upper air temperature bias settng
when used with the new version. I had not actually had reports of this, but
ran across it while experimenting with older files to find the problem in
Version 2016 (Build 1.0, June 14, 2016) had the following changes relative
to Version 2016, Build 1.0 (described below):
- In WXSIM, there were sporadic reports of "No READY or GFS data found".
In some cases, at least, this was actually not "true"; data WERE
found, but were judged to be "unbelievable". Specifically, every
now and then GFS reports a relative humidity lower than 1%. I did have a filter
to reject anything that low or lower, but have now eased up on the restriction,
so WXSIM will "believe" values as low as 0.01%. These very low RH's
seem to happen only in upper levels of the atmosphere, so they really won't
hurt the surface forecast, anyway.
- In wret.exe, a couple of people recently reported an error #9 (subscript
out of range). I found this to be because these users had 10,000 or more forecasts
archived! I had not considered that large of a number when dimensioning arrays
(up to 9999), but in fact people running close to 20 forecasts a day for a
year and half can indeed collect that many! That's frankly too many for wret.exe/autolearn
to use anyway, so the oldest forecasts (.wxf) should be placed in another
folder for safekeeping. However, I don't want users to ever have to see the
error, so I've "pre-empted" it, by checking the numebr of forecasts
before the error gets a chance to occur. Now a message box appears, instructing
the user to get the number down under 10,000 by moving the older forecasts
to another folder.
- Protections were added in the functions calculating dew point from vapor
pressure, and dew point from temperature and relative humidity, in order to
handle entered or imported relative humidity values of zero.
Version 2016 (Build 1.0, March 29, 2016) had the following changes relative
to Version 2015, Build 2.1 (described below):
- A bug, which reversed the sign of 'residual' corrections to minimum temperatures
when using WXSIM-Lite, was corrected. The errors were usually only a few tenths
of a degree, but in rare cases could be large enough to make the 'minimum'
higher than the lowest output temperature.
- Modifications were made to the way WXSIM uses learned bias corrections from
cor.txt (i.e. created via autolearn.exe) along with WXSIM-Lite data, so that
out-of-range values are not only limited, but the values to be written into
.wxf files are made so that they would not have led to limit exceedence in
the first place.
- WXSIM now modifies ingested WXSIM-Lite data by taking the values from fdata.txt
and applying a climatological filter, to weakly trend GFS-derived temperatures
and dew points toward seasonal normals.
- Changes were made in wret.exe to modify values from previously used correction
factors if these were determined using earlier versions of WXSIM. This is
because a study of about 20 sites' correction factors with and without autolearn
showed biases due to items 1 through 3, above.
- wret.exe was changed to allow incorporation of learned bias corrections
from the same season as present, from one and two years ago, as analyzed by
autolearn using correc.txt. These data are also adjusted if they come from
periods when an earlier version of WXSIM was used with WXSIM-Lite (i.e. before
this current release date, or more specifically February 20, 2016, when the
first beta version was released).
- The checks for lines of bad GFS data, for both home site and advection,
were made much more robust to shield against implausible (and often error-producing)
values being imported into WXSIM. These bad values have been very rare - usually
only one error in 81 lines of data if they happen at all - and are almost
never on consecutive lines, so the algorithms here replace bad values with
ones interpolated from before and after the line with errors. One error in
a line is deemed reason enough to replace ther whole line.
- An error message in wret.exe, which could result from a corrupt .wxf file,
was enhanced with instructions about how to correct the problem.
- An option (during customization, so this will not affect existing jobs,
unless I custom add the feature to your cty.fdt file) has been added to model
the effect of sloped terrain, so that solar energy absorbed by the surface
takes this into account. Along with this, shading from mountains (usually
just after sunrise or before sunset) is enabled, with two "mountains"
(and "eastern" one and a "western" one) specifiable. WXSIM
tracks solar altitude and azimuth, and can now "eclipse" the sun
at the appropriate times.
- More information was added to a number of error and irregularity messages
(especially the ones reported by wxerr.exe after a WXSIM run completes), in
order to help the user diagnose the problem.
- Information was added to the prompt which appears when the DST (Daylight
Saving Time) box is changed. This prompt offers the opportunity to make the
similar settings in wret.exe and wxsimate.exe the same as in wxsim.exe. However,
this change takes effect only if those programs are closed, as the prompt
now indicates. (This setting can be changed independently in all three programs
Version 2015 (Build 2.1, completed November 3, 2015) has the following changes
relative to Version 2015, Build 2.0 (described below):
- Options for customization were added to enable automatic elevation-based
adjustment for the 'home' METAR and (separately) SYNOP sites' imported temperature
and dew point values. This does not affect customers who ordered before October
24, 2015 and will not often be used in customizations. The purpose of these
additions is to enabled users in mountainous areas, *without* home weather
stations, to get useful initial surface conditions from METAR or SYNOP import.
Version 2015 (Build 2.0, completed August 8, 2015) had the following changes
relative to Version 2015, Build 1.3 (described below):
- A safeguard was added (actually, it had been accidentally disabled in some
earlier version) to avoid forecast errors which could result from use of a
too-small set of historical data when using the learning routine (in autolearn
or wret) in conjunction with WXSIM-Lite.
- The enhanced nocturnal decoupling routine (mainly useful for medium-large
islands, such as New Zealand) has been modified, making it slightly stronger
(hence colder nighttime lows in clear, calm conditions) but also phasing it
in and out with the seasons, as it is needed primarily in winter.
- A warning message was added, if WXSIM imports local station data showing
more than 30 inches (762 mm) of precipitation in the last 30 days, which is
a likely consequence of choosing inches as the units in Weather Display or
Cumuls log files, when in fact they are being recorded in millimeters, in
- wret.exe can now function with autolearn via WXSIMPRO (theoptional multi-sitecontroller
program), so that separate learned bias correction factors can beautomatically
determined for each site.
Version 2015 (Build 1.3, March 10, 2015) had the following changes relative
to Version 2015, Build 1.2 (described below):
- Air density at turbine height was added as a variable to latestturbine.csv
(a file produced only for sites customized for wind turbine predictions).
Version 2015 (Build 1.2, March 10, 2015) had the following changes relative
to Version 2015, Build 1.1 (described below):
- Better error trapping was added to prevent users from attempting forecast
runs using WXSIM-Lite data, if WXSIM-Lite has not yet been used to produce
- A very rare error, which could produce an 'Invalid property value' error
at the very end of a forecast run, has been addressed and probably corrected
(according to initial tests from the users reporting the error). This resulted
from occasional spurious attempts to open the advection form at or near the
end of a forecast run. While the exact cause of this has not been identified,
the protection consists of having the form unload itself if activated after
98% of the forecast run is complete. A log file called adv_activate_error_log
is now created to document occasions on which this protection is called upon,
even when the error is successfully avoided.
- The default bias corrections to GFS data on the 4th tab under Preferences/Settings
have been changed to neutral values, presuming that the new 0.25 degree GFS
data has no known temperature, cloudiness, or precipitation biases.
- The data retrieval program, wret.exe, now has a more informative message
when it traps errors due to misplaced data in log files (such as from Weather
Version 2015 (Build 1.1, January 2, 2015) had the following changes relative
to Version 2015, Build 1.0 (described below):
- Better error trapping was added to prevent users from attempting forecast
runs using WXSIM-Lite data, if WXSIM-Lite has not yet been used to produce
- A very rare error, which could produce an 'Invalid property value' error
at the very end of a forecast run, has been addressed and probably corrected
(according to initial tests from the user reporting the error)
Version 2015 (Build 1.0, December 31, 2014) had the following changes relative
to version 12.12.1 (described below):
- First, a new naming convention has been adopted, using build numbers and
major release years, starting with 2015 being released just prior to that
- Most importantly, WXSIM has been modified to use data from the new companion
program, WXSIM-Lite. That program (included in the WXSIM installation and
upgrade packages) makes forecasts using a different approach, in which GFS
(and later perhaps additional model data) is downloaded, adjusted and interpolated
in various ways, and then saved for later comparison to actual data from a
personal weather station. WXSIM-Lite can then analyze the results to build
a sophisticated set of bias corrections to apply to future forecasts, somewhat
like WXSIM's own 'learning' routine. Months of testing have shown WXSIM-Lite's
temperature forecasts to be generally more accurate - by about 15 percent,
and maybe more for some sites - than WXSIM's own forecasts. However, data
also suggest that WXSIM's forecasts have indepent value, especially for short
term and nighttime forecasts, so the potential exists for mixing of WXSIM
and WXSIM-Lite forecasts to produce forecasts better than either alone (though
only a bit better than WXSIM-Lite's forecasts). This new version of WXSIM
allows WXSIM-Lite's temperature and dew point forecasts to influence WXSIM's
output to a user-specificied extent. This is almost sure to produce the biggest
single improvement in WXSIM's accuracy in many years. It is possible (and
advantantageous) to use WXSIM's own learning feature concurrently with incorporation
of WXSIM'Lite's data. Information is stored in WXSIM's forecasts to indicate
the extent to which WXSIM-Lite's data was mixed in, and this information is
carefully taken into account in later use of learned bias corrections. In
other words, both programs can 'learn' at the same time without conflict or
any need of second-guessing on the part of the user.
- IMPORTANT NOTES: The ability to mix in WXSIM-Lite data is available in WXSIM's
professional mode only. Also, the current plan is for WXSIM-Lite's special
data to become subscription only (at a very low rate, but enough to cover
server and ongoing development costs) at a later date, perhaps in late February,
2015. Meanwhile, the data are temporarily free of charge.
- The Auto Run form under the Start menu item has been expanded and organized
(and renamed as 'Auto Run and Other Settings'), and now includes access to
the form for mixing in WXSIM-Lite data and also control over end-of-forecast
settings formerly accessible only (and perhaps inconveniently) on the Output
- A new option to alter the appearance of WXSIM's main programs has been added
(button on the new 'Auto Run and Other Settings' form). This allows use of
'XP and later Windows Styles', if you are using Windows 7 or later (it actually
causes some bad display of option buttons in XP itself). You can toggle back
and forth between the style options to see what you like best.
- Various cosmetic and informational changes were made, including a new color
scheme for WXSIM's Data Entry form.
- Potential use of imported GFS data has been expanded to include up to 9
days of data (the maximum length of a WXSIM forecast), instead of the previous
7.5 day maximum. This will become relevant when the GFS data downloaded by
WXSIMATE is changed over to the upcoming 0.25 degree resolution version. The
implementation date of this is uncertain as of this writing, but hopefully
will be done by sometime in February, 2015.
- Wording of the convective bulletins about 'Showers unlikely' and 'Showers
very unlikely' has been changed by adding the word 'Convective', so that contradictory-looking
text about showers being unlikely while (stable) rain is forecast will no
- The autolearn.exe program has been updated to version 2.0, which allows
graphs of the history from correc.txt
- The Daylight Saving Time setting (always a pain in the past, I know) is
a bit simpler now. When you change the check box in WXSIM, it should make
the same change in wret.exe and wxsimate.exe as well (that does not work in
reverse, though). I do have a "warning" system in place, which looks
for evidence that the setting does not go with the computer's clock. It's
still a bit complicated, though, because there are reasons (at least for me)
to alter the setting (for example, in wret.exe, if I'm analyzing old forecasts
from another season). So, the change is not made automatically. However, it
should warn you (at least the first time DST status changes) and you can now
make the change globally.
- A small bug was fixed: at the beginning of the forecast, the advection routine
was displaying (though apparently not actually using) a "normal"
temperature (for the time and date), instead of the actual temperature, as
the "home" temperature, against which actual upwind temperatures
are compared to generate an advection profile. This has been corrected so
that the actual temperature at the time is displayed.
Version 12.12.1 (May 3, 2014) had the following changes relative to Version
12.12 (described below):
- The ability to forecast wind speeds at specified heights above the ground,
for use in forecasting wind turbine power output, was added. This additional
data is displayed, along with other relevant data, in a new output file called
latestturbine.csv. This feature is not generally available to all users, but
is something I can customize specifically for the site, based on turbine height,
surface roughness, and (optionally) past wind history.
- Warnings and measures have been added to wret.exe to prevent users from
trying to use 'combined' data in the analysis for learned bias corrections.
The purpose of the 'Combine' box on the comparison to actuals graph is to
allow display of hourly-averaged data, not to develop correction factors.
- A bug in wret.exe, which could cause an 'Invalid procedure call' error,
has been corrected.
- Another bug in wret.exe, which occasionally and mistakenly caused rejection
of data (for developing learned bias corrections) has been corrected. This
was a simply typographical error in a variable name in my code.
- wret.exe now is able to circumvent a problem involving reading of WeatherLink
data. It seems that occasionally, the first couple days of the month (for
one user, anyway) have some garbled data, either due to the .wlk files themselves,
or perhaps to WXSIMATE's interpretation of that data (which is binary "gobble-dee-gook").
It now skips over such stuff until it find reliable data and uses only that.
This affects the autolearn and Auto Select routines, but again, only if you
are using WeatherLink.
- wxsim.exe has a change which should have no effect whatsoever on any existing
customization. This is a customizable feature controlling the extent of mixing
in light winds under strong inversions, primarily in arctic regions. Generally,
the problem (based on data from a site in Yukon, Canada) was that such mixing
was too weak, and this change makes it possible for me to strengthn it, if
needed, in customizing.
- An erroneous message telling the user to uncheck the 'Run optional DOS batch
file' (when it was in fact not checked) in WXSIM has been corrected. Actually,
I am not sure if this bug was present in the official version 12.12, or if
it was only in a beta version since then. Either way, it is now corrected.
- A rarely occurring, but longstanding (several years!) error #6 ('overflow')
in both wxsim.exe and wret.exe has been solved. This error occurred when the
'Shell' command was called to open another program (such as wxsim.exe opening
wret.exe at the end of a forecast). I finally discovered that it was a case
of my having declared the 'task number' to be an integer, but occasionally,
on some computers, the system would assign a number bigger than 32767, which
is the highest integer allowed. I have now declared this variable as 'double
precision', which should totally sove this problem.
Version 12.12 (February 5, 2014) hadthe following changes relative to Version
12.11 (described below):
- A more sophisticated treatment of the learned bias corrections has been
implemented. This modifies the "slope bias correction" in such a
way that there is a smooth tail-off in the effect when departures from normal
temperature are greater than the average amount of departure from normal in
the analysis. Something like this existed in previous version, but the function
was discontinuous in slope and did not reduce the bias sufficiently. This
one reduces it to about a third of the "learned" value when departures
are more than about twice the average amount of departure. Also, a very thorough
statistical analysis of thousands of forecasts, combined with studies using
randomly generated data in Excel, suggested that extending small sample sizes
of data to a larger range of conditions presents a problem: part of the error
in error versus forecast departure from normal is an artifact of using (necessarily)
the forecast departure as a basis, instead of the actual departure as a basis.
Essentially, a too-warm forecast also tends to be an "above normal"
forecast. I have now standardized the slope to be defined as appropriate when
standard deviation of departure from normal is twice the standard deviation
of the error itself. Outside this range, the slope is altered towards being
a bit more "extreme" (allowing greater departures from normal).
I believe this change will allow better transition between seasons, for instance
by anticipating the possibility of larger temperature excursions in the fall,
after a monotonous summer.
- Changes were made in wret.exe to the plots of error versus date and versus
departure from normal, to increase readability and reflect the changes listed
in (1), above.
- Bitmap plots, named errdate.bmp and errdep.bmp, are now made when the plots
mentioned in (2) above are viewed, or when autolearn.exe completes its run
- The default "distance ratio" on the advection form was reduced
from 1.15 to 1.1, as this now appears to make more accurate fits for upwind
- An occasional overflow error (Visual Basic error number 6) resulting from
the use of the Cint function in Visual Basic, with values over 32,767, was
corrected by using Int(x+.5) instead. This error may have existed for a long
time, but the change in the distance ration from 1.15 to 1.1 may have made
it more likely to show up.
- A routine intended to better model mixing out of morning temperature inversions
was found to have bad effects (a brief dip in temperature around noon) on
cloudy days with light winds, mainly in winter at high latitudes. This has
been corrected by phasing the effect out as cloud cover increases.
- Changes were made to hopefully avert a rare printer error in cases when
no printing was requested.
- Changes were made to slightly reduce the diurnal temperature range and also
the rate of air mass modification in colder than normal weather. This was
based on careful study and re-running of forecasts of historical data, mainly
during arctic air outbreaks.
- A sort of climatological filtering has been applied when GFS model data
is being used, so that temperatures past about 2 days into the forecast are
trended slightly towards normal. This "correction" is actually only
about half the theoretically optimum value, so as to preserve some of the
underlying run-to-run variability, but still tone down unrealistic extremes
which crop up at times. The treatment is season and location specific, by
taking into consideration typical standard deviation of error in GFS data
along with typical standard deviation of actual temperature.
- Maximum daily snow depth was added (to the existing average daily snow depth)
in the Supplemental Dat section in the scrolling text output and in latest.txt.
- Internal changes were made in the main forecast module to allow room for
the additional code.
- The learned bias corrections displayed under Preferences/Settings in WXSIM
are now in familiar units (i.e. degrees F or C) instead of the cryptic raw
values diplsayed in previous versions.
- A failure to clear out old data had sometimes caused brief (only in the
first three hours or less of the forecast) excursions, mainly in barometric
pressure, when using GFS data. This has been corrected.
- A very slight increase in the weighting of the "clear thickness maxiumum"
(an estimate of clear sky maximum temperature based on the thickness of the
lowest 130 millibars or so of the atmosphere) was made, so that daily maximum
temperatures will be constrained slightly (a couple of tenths of a degree,
typically) closer to this figure.
Version 12.11 (January 1, 2014) had the following changes relative to Version
12.10.2 (described below):
- An oversight in wret.exe caused (only for users of Cumulus) the Comparison
to Actuals, as well as the learning routines (through Auto Select or
autolearn.exe) to jump back to January, 2013 after December 31, 2013, instead
of proceeding to January, 2014. This has been corrected. Since the change
involves only wret.exe and the official release was just yesterday, I am simply
repackaging the installer with this change, rather than renaming the entire
- Options for sea surface temperature on the Diurnal Breeze form were made
more simple and explicit. There are now option buttons for either using default
sea temperatures or user-entered ones. These settings take effect as soon
as the OK button is pressed, and are saved for future runs until changed.
- The default (climatological) sea temperature now changes with each day of
the forecast, rather than retaining the value from the first day.
- A typographical error in a warning about far-from-normal sea surface temperatures
was corrected: "10.8" Celsius was changed to "6" Celsius.
- Messages about missing local calibration data (from localcal.txt) are now
deferred to the auxiliary external messaging program (wxerr.exe) so that they
will not interrupt auto runs.
- The 'Offset' and 'Range' factors in WXSIM were previously simply stored
values which the user needed to keep consistent with 'Dep' and 'Rng' in wret.exe
(which are used in developing learned bias correction factors through Auto
Select or autolearn.exe). They were not - and still are not - used in any
way in generating a forecast, but are written into latest.wxf as a record
of the user's intent in wret.exe at the time of the forecast. Changes have
been made so that the values shown are read, both at forecast time and when
the form is opened, from wret.exe's initialization file, retini.txt. Also,
the boxes displaying the two values in WXSIM are now disabled for user modification,
since they need to be enetered in wret.exe to be used.
- An unused form (gfsadj, whose functions were incorporated into the tabbed
form under Preferences/Settings several versions ago) was deleted to reduce
- Error trapping was improved in wret.exe to avoid crashes when latest.wxf
is not found.
- Changes were made in the auto select ("learning") routine of wret.exe
to avoid a "file already open" error that was reported by two users.
- Error trapping was improved in wret.exe's comparison to actuals and learning
routines, by displaying the last line read from a potentially faulty weather
station software log file in the error message. This allows the user to quickly
find and correct the problem in the log file. The example motivating this
change was a case of a few dates being out of order in a Weather Display log
file, which caused a 'Subscript out of range' error in wret.exe.
- Minor cosmetic changes were made in wret.exe.
- Appropriate changes were made to WXSIM's blue-text help file.
- A bug which allowed the year to remain the same in .csv files, when January
1 is reached, was fixed. The change also applies to other routines which are
functions of the year, such as climate and solar forcings.
- A bug similar to that above, involving the UTC time stamp in the lastret.txt
file, was fixed in wret.exe. This also now has correct output across the change
to the new year.
- In wret.exe, bitmap graphics are now automatically produced for the error
as function of date and of departure from normal graphs when these are displayed.
Also, these are briefly displayed, closed, and graphics created auto,atically
by autolearn.exe when that program is used.
- Small wording changes were made in the output of wret.exe's auto select
- Small changes were made in the advection form's output for quality of the
curvature fit. Previously, erroneous values for "Spd" and "%"
were briefly shown (but not actually used in the final fit). Also, the advection
site map now shows the number of sites actually used for the fit rather than
the total number found.
- On the data import form, the number of sites found for advection was sometimes
shown too large by one (when MOS runs out and the program defaults to GFS).
This has been corrected.
- A warning message now appears in WXSIM if the status of the DST (Daylight
Saving Time) box does not match the status derived from internal data for
the computer (derived from a comparison of the GMT system time and the adjusted
time on the computer's clock, considering WXSIM's time zone information for
the site). This message occurs only at start-up of WXSIM (as an internal message
box) or in auto run at the end of a forecast (as an external message box which
does not interfere with the forecast). There may be some users who run forecasts
for sites outside of the computer's time zone. To accommodate this, there
is an option to prevent the message from appearing after the first time.
- A possible fix to a problem involving a rare problem of failing to get fresh
GFS data on the first run of the day has been implemented. Actually, the code
for this fix existed in the last two versions, but was probably ineffective
because a variable had not been declared globally; now it has.
- Small cosmetic changes were made to a couple of forms.
Version 12.10.2, (September 23, 2013) had the following changes relative to
Version 12.10.1 (described below):
- One or more causes of an occasional error 52 (bad file name or number) were
corrected. As of this writing, such an error is being reported by only one
user, with the cause seemingly something very system-dependent. If such an
error is still encountered, two possible workarounds are UNchecking 'Minimize
forms', CHECKING 'Omit log files' (both these on the Auto Run form), or (an
almost certain fix) having WXSIM close after auto runs, and be reopened by
a third-party scheduler.
- Wording was improved to be more instructive in the case of messages about
not not having imported model data.
- A bug which often caused failure to use local station data in the calibration
run was corrected. A separate, but related error was fixed in WXSIMATE as
of version 5.3.2, completely correcting this type of error (which had only
very minor effects on most forecasts).
- Autolearn.exe has been updated (now version 1.2) to improve clarity of use
and avoid common user mistakes in connection with wret.exe, which also had
small improvements in wording.
- wret.exe now formats correc.txt properly even with regional and language
settings using commas as decimal separators (previously older data was split
awkwardly into multiple lines).
Version 12.10.1 (August 16, 2013) had the following changes relative to Version
12.10 (described below):
- A new program called AutoLearn has been added to the WXSIM suite. It allows
scheduling of automated "learning" runs (for use in WXSIM's Professional
Mode) by wret.exe, and changes were made in wret.exe to accommodate this.
AutoLearn is actually a separate program, with a registration fee for full-featured
use. In demo mode, it has a fixed 10 day analysis period, which is too short
for optimal results, but can still give users a good look at how it works.
Note that this is for convenience only, as manual use of the AutoSelect feature
in wret.exe accomplishes the same task.
- WXSIM's response to the learned bias correction factors has been fine-tuned.
Testing revealed that, under normal use (including GFS and FOUS data and advection),
the overall temperature correction and the "slope" parameter supplied
only just over half the needed correction on the first try, so that a period
of time two or three times the analysis period (which is often months) would
be needed for essentially full response, by which time short-term and even
seasonal effects would be largely blurred out. The range and dew point factors
were fairly well-tuned already, but all four parameters have now been carefully
adjusted to yield full response on the first use, with or without GFS, FOUS,
or advection data.
- The range of allowed values in the 'slope' correction factor (which influences
the 'pull' towards climatological normal temperatures) has been expanded to
+/- 40% (instead of the previous 25%), in light of data which showed these
more extrme settings are sometimes needed. However, this usually occurs in
rather monotonous weather with few air mass changes, and extrapolation to
more extreme temperature events may not be warranted. For this reason, the
slope factor now contains information about the range of departures from normal
in the anaylsis, and WXSIM uses this to reduce the effect to no more than
+/-20% for temperatures well outside this range, smoothly transitioning to
this figure with increasing departure from normal.
- Minor informational and cosmetic changes were made in both WXSIM and wret.exe.
These include parenthetical information in WXSIM's File menu that retrieving
data means opening wret.exe, and that the Cull/Append routine is seldom used.
In wret.exe, departure from normal is now shown to be an 80%/20% mix of forecast
and actual values (in that order, and as they have been for some time) and
instead of average forecast and actual departure from normal, the mean values
for the cooler and warmer halves of this 80:20 mix are shown.
- Clicking the 'Cumulus' option on the Comparison to Actuals form now enables
entry of text, regardless of prior choice (previously, it was necessary to
have checked Weather Display first - an oversight in the implementation of
Cumulus use for this.
- It was found that, under certain scheduling conditions, auto run could generate
messages that the data were over 24 hours old, on the first run of the day.
This also significantly impacted the accuracy of those forecasts. Changes
have now been made so that this error should no longer occur (though the message
should still appear if the data actually ARE over 24 hours old).
- I discovered (in studying Finnish users' data) an odd shape to the diurnal
temperature curve in the May-July period. The temperature would rise quickly
in the morning, then warm almost linearly until a somewhat too-late high temperature
(about an hour or two later than reality). I traced this to an oversight in
a very old routine which estimates the times of day when the temperature should
be near the daily mean, as these figures help inform the onset of mixing with
daytime heating. I apparently had not tested this at these latitudes near
the solstice, so the problem has been there a long time! This has now been
fixed. The change to wxsim.exe is significant if you live more than 45 degrees
from the equator and are having daylight exceeding 15 hours, the difference
being very minor until you reach about 60 degrees latitude, but very important
near and north of the arctic circle.
- There is now a trap set for errors at the end of an auto run run, at the
point where WXSIM attempts to boot wret.exe to make graphics and the lastret.txt
file. Such errors have been elusive as they seem to be sensitive to other
processes on the computer, because rebooting would sometimes prevent the problems
(which tended to be intermittent anyway). It should catch any error #6 (overflow)
errors and just act like nothing happened (which I think will be OK). It might
catch others, too, with a message, and then hopefully keep going. This error
may have also led to bad .wxf files and errors in wret.exe. Incidentally,
such errors were the reason for the 'Ext boot' option (check box near the
'Graphic' check box on the Output form). This option remains, just in case
it's still ever needed.
- A change was made which should prevent a certain 'file already open' error.
- The document 'Evaluating Temperature Forecast Accuracy in WXSIM'(written
on July 6, so that some of the screen shots are very slightly outdated) was
made part of the standard WXSIM distribution package.
Version 12.10 (June 30, 2013) had the following changes relative to Version
12.9 (described below):
- The sea breeze routine's warning system for abnormal sea surface temperatures
has been changed so that only discrepancies larger than 6 Celsius degrees
(10.8 Fahrensheit degrees) will trigger a message that actually interrupts
program execution. Discrepanices greater than 3 Celsius degrees (5.4 Fahrenheit
degrees), but no more than 6 C will now trigger only an external message which
does not interrupt the program. Discrepancies larger than 1.5 degrees will
be recorded in the file seatempanomalies.txt.
- Sea level equivalent water temperature, and also normal default values for
water temperature and its sea level equivalent are now displayed on the diurnal
- Small informational and cosmetic changes were made to the Save Data form.
- Internal changes were made regarding the reading of registration codes.
- A bug in the soil data routine, which sometimes caused it to fail to read
station data (especially when less than four depths are used and blanks instead
of "999" were entered in WXSIMATE) was corrected. Slight changes
in the extrapolation of moisture to non-measured depths were made also.
- A message was added to WXSIM's Soil Data Entry form to prevent users from
checking more than 5 agricultural output variables (though all variables are
saved for later viewing in wret.exe).
- Changes were made to the way in which layer relative humidities from NAM
FOUS data (North American users only) are interpreted as cloud cover. In particular,
extensive research showed that, with steep lapse rates (such as in summer),
higher relative humidities are needed to produce overcast conditions (perhaps
because areas of downdrafts produce clearer patches) in levels 2 and 3. The
main effect of this change is that some overcast or mostly cloudy summer forecasts
will now be mostly or partly cloudy instead.
- It was found that - when FOUS and READY or GFS data were used together -
the averaging was (inappropriately) somewhat dependent on the time interval
(a function of the output interval and the number if iterations per interval).
Changes were made in the way FOUS influences cloud cover and precipitation,
so that these discrepancies are reduced to a trivial level, especially if
the time interval is kept to 10 minutes or (preferably) less. This occurs,
for example, with an output interval of 30 minutes and 3 iterations per interval
(while 6 would be better, for a 5 minute interval).
- An internal typographical error in WXSIM, which could have (but probably
never did) affected sunset times in unusual circumstances, was corrected.
- Comparison to actuals is now avaiable in wret.exe for Cumulus. This also
makes it possible to use (in professional mode) the "learning" routine
- Informational changes (an extra decimal place, number of forecasts analyzed,
time to complete the run, etc.) were made to the Auto Select results in wret.exe.
- Major improvements were made to wret.exe's Comparison to Actuals and Auto
Select routines. A wealth of statistical data is (optionally) displayed, both
graphically and as text on the comparison graphs. These include not only net
and mean absolute errors, but root-mean-square errors and standard deviation
of error, as averages over periods ranging from a day to 30 minutes.
- More information was added to the Auto Select output in wret.exe, such as
indicators of four different types of reasons for data rejection, and user
input regarding criteria for rejection. Also, message boxes have been added
for guidance in the use of this routine.
- A UTC date/time stamp was added to the end of each line of data in lastret.txt
(produced by wret.exe), mainly to help developers of php scripts for displaying
WXSIM forecast data graphically.
- Minor formatting changes were made to lastret.txt's output, including a
one decimal place (instead of a whole number) for sea level pressure in millibars
(hectopascals) and an extra space in front of lifting condensation level if
its value reaches or exceeds 10,000 (this should happen only if using feet
- Error handling has been improved in wret.exe, so that when it encounters
a corrupt forecast file (caused by improper closure of WXSIM - by the user,
due to an error, or due to a power outage), it advises the user of the reason
for the error and gives instructions for how to remedy it (previously it just
gave an error message and crashed the program).
- Very minor cosmetic and informational changes (i.e. punctuation and spelling)
were made to both wret.exe and wxsim.exe.
Version 12.9 (March 4, 2013) had the following changes relative to Version
12.8.11 (described below):
- A protection has been added to handle the possibility of the site specified
in custinit.txt not having corresponding METAR code and name with any site
in cty.fdt. Previously, error messages such as "Dew point cannot exceed
temperature" may have appeared in such cases (which would be extremely
rare, indicating probably file corruption).
- The messages "Dew point cannot exceed temperature" and "Unrealistic
barometric pressure" are now skipped in auto run mode, while the dew
point is quietly set to the temperature and the barometric pressure to the
world-wide sea level mean. These changes also occur even if the messages do
appear (in manual mode).
- The routine for writing the latest.csv file was inappropriately combining
weather types 1 and 2 and writing this as type 1 (while correctly writing
type 2). This has been corrected.
- A check on program startup (upon loading site data) has been added to see
if the computer uses commas as a decimal separator. If so, the setting 'Use
semicolons for .csv files' defaults to true (checked, on the Auto Run form)
in order to avoid errors in the writing of the .csv files.
- The function for calculating distance to the sun was fine-tuned, yielding
a slightly smaller difference between perihelion and aphelion and a shift
of a bit less than a day. The maximum effect on solar radiation is at the
surface is no more than as 3 watts per square meter, and resulting temperature
effects in the program are on the order of a tenth of a degree. The main reason
for the change was to make solar radiation outputs as accurate as possible.
Also, I did a fresh study of the solar radiation model, and found that the
only changes appropriate were the above.
- A carefully devised function for the 11 year solar irradiance cycle was
constructed, including an assumption that over the next cycle or two, the
sun may enter a relatively quiet phase, perhaps approaching that of the Dalton
minimum in the early 1800's. The peak-to-valley variation of about 1 watt
per square meter is assumed to decrease to about 0.7 w/m^2, with a drop in
the average by about 1 W/m^2. I assumed (with little basis, other than comparison
to the Dalton and Maunder minima) that this dip may last about 50 years. Actually,
direct effects of this on temperature are trivial (on the order of a tenth
of a degree) compared to other sources of error. I mainly included it in case
it is of further interest later.
- The "use global warming" option has been updated, based on a recent
(last 12 years or more) leveling-off of the previously rising global mean
temperature. This "flat" stretch is documented in both the NASA
GISTEMP and Hadley Center HADCRUT data. It may be partially explained by recent
small decreases in solar activity, both as part of the normal cycle and changes
in the cycle itself. To incorporate this, I applied the solar cycle model
described in (6), and also applied a gentle concave up curvature whereas earlier
I had it linear. It still produces about 3 Celsius degrees of warming between
1965 and 2100, but with only a slight rise before 2020.
- This is really an addition to WXSIMATE, not WXSIM per se, but is relevant
enough to mention here: WXSIMATE can now read data from the program Cumulus,
by Sandaysoft, in addition to the previous set of software packages with which
it is compatible: Davis WeatherLink, Brian Hamilton's Weather Display, Ambient's
Virtual Weather Station, and Quimisur (a Spanish company). At this time, the
use of Cumulus is limited in three ways: (1) the "compare to actuals"
tool in wret.exe is not functional for Cumulus, (2) the associated "learning"
routine are not functional in wret.exe, and (3) soil temperature and moisture
data are not read. (2) and (3) are features of WXSIM's professional mode and
therefore do not affect use in standard mode. So, standard mode is very nearly
full-featured for use with Cumulus. I may add some or all of these features
in the future, but do not have any current goals for when this might get done.
- Reports from high-latitude users (i.e. Finland) indicated that WXSIM was
reducing snow depth too rapidly in sub-freezing weather. Investigation, backed
by research such as in this study: http://www.igsoc.org:8080/annals/26/igs_annals_vol26_year1998_pg125-130.pdf
showed that the main problem was not melting or sublimation, but overly rapid
compaction of the snow under its own weight. Changes were made to generally
reduce this rate, and also make it temperature dependent (slower compaction
at lower temperatures).
- A change was made which should fix the occasionally reported 'forgetting'
of the 'RAOB' and 'READY or GFS' check box settings on the data import form
(assuming the problem found was the only cause). When unrecognized and not
corrected, this problem led to messages about no model data being found, and
the resulting forecasts were generally poor.
- A variety of messages which previously interrupted program execution, awaiting
a user response, have now been handed over to a new, small program (included
in the WXSIM upgrade and demonstration packages) dedicated to their display.
This allows WXSIM to continue and complete the forecast and yet assures that
the users knows about the problem(s), which are usually about missing data.
The messages are also displayed in a text file called msglog.txt.
- A program called trimlog.exe has been included in the package (but not given
a Desktop icon at this point). This is a tool for users of the Weather Display
program who may find import into WXSIMATE to be slow. Trimlog can run on its
own scheduler to produce much smaller versions of the Weather Display log
files, allowing import time to be cut by a factor of almost 10.
Version 12.8.11 (July 16, 2012) had the following changes relative to Version
12.8.10 (described below):
- The 'suspicious initial wind data' message in auto run now appears only
under more extreme conditions, 32 mile per hour discrepancy as opposed to
16, though values over 16 are still reduced to 16 before use.
- A limit was placed on the lapse rate between levels 3 (approximately 700
mb, for most sites) and 4 (500 mb), to keep it a bit short of the dry adiabatic
lapse rate. The value used is slightly dependent on surface elevation and
is based on considerable research of historical RAOB soundings. Also, a bug
in a beta release of this version has been corrected in the final one here.
- For sites with actual (not adjusted to sea level) surface pressures below
970 mb, the Total Totals Index (TT) has been modified by mixing it with an
alternate definition (called HLTT or High Level Total Totals) in which 700
mb replaced the original 850 mb in the formula. The K, KO, and Showalter indices
are modified similarly but indirectly, based on the change between TTI and
HLTT. This indirect method was used because, while I did have some data correlating
TT, HLTT, and convective threat, I did not have separate data correlating
700 mb version of the other indices with such threats. The new indices are
equal to the old ones with surface pressure above 970 mb, and gradually transition
to the high level versions as a surface pressure of 850 mb is reached. This
change was made because some moderate to high elevation sites were getting
overly aggressive convective indices.
- The 'reduce superadiabatic' routine was modified to have less effect for
surface pressures below 970 mb (that is for higher elevation sites). When
the previous version was used for these sites, high temperatures became somewhat
too warm and the air too unstable. The effect now transitions gradually from
its original value for surface pressures above 970 mb, to half that around
945 mb, to very small but non-zero values at much lower pressures.
- The READY/GFS bias correction (top of tab 4 under Preferences/Settings)
has been modified so that, while the initial temperature correction is the
same as before (with a given setting), the trend part is reduced to 0.67 of
its original value. This was done to correct a tendency, in long range (over
a week) forecasts for too-large of a drift to occur. For instance, while an
input positive value of, say 0.5, would produce only a modest temperature
for the first few days, later in the forecast the change would become too
large. The change shouldproduce more consistent day-to-day temperatures (aside
from a multitude of other effects, of course).
- A bug, which could produce a 'file already open' error after a message about
GFS data being for the wrong site, has been fixed (the message can still appear,
but hopefully not the error that could follow it).
- Many new avenues of communication have been opened between WXSIM and the
optional multi-site controller program, WXSIMPRO. One example is a short file
called wxsimopen.txt, which should consist of the number 1 if WXSIM is open,
and 0 if it is not. Also, WXSIMPRO can now optionally have WXSIM default to
climatological normal sea surface temperatures instead of retaining values
from an earlier run. Messages related to this in both programs have had wording
changes. Most of these changes are not visible when not using WXSIMPRO.
- A change was made in the Retirevel program (wret.exe) to enable the Auto
Select routine to successfully bridge across from one month to another (previously,
for VWS data, forecasts spanning months were rejected from the analysis).
Months were already bridged successfully for Weather Display and WeatherLink
data, at least.
Version 12.8.10 (December 19, 2011) had the following changes relative to Version
12.8.9 (described below):
- A bug, which could occasionally cause an 'invalid property value' error,
has been fixed. This error would occur if WXSIMATE somehow (perhaps through
some kind of interruption) failed to finish writing the localcal.txt file.
It is still possible WXSIMATE may do this, but there is only a trivial loss
of data which would have no perceptible effect on WXSIM's forecast. Now WXSIM
should be able to handle this situation without error or interruption.
Version 12.8.9 (November 23, 2011) had the following changes relative to Version
12.8.8 (described below):
- The wret.exe module's 'Auto Select' routine for determining learned bias
correction factors has been improved in two ways. First, a careful study of
the effect of corrections motivated a change in how the 'tendency towards
normal' factor is determined. These factors should now be slightly more conservative,
and accurate, than before. Second, the heavier weighting of more recent data
is now an option (the 'Weight recent more' box must be checked for this),
with the default being to weight all data equally. The equal weighting is
a bit 'safer', but unseasonal spells may still call for the heavier recent
- A few places in wret.exe allowed values to be printed in lastret.txt with
enough digits to run columns together (an earlier attempt to correct this
still left loopholes where the figures 100.0 and 10.0 could appear). This
has been corrected.
- Minor changes were made to the help file, such as noting that the NGM model
is no longer in production (as of 2009).
Version 12.8.8 (July 19, 2011, and August 12 for the wret.exe module), and
has the following changes relative to Version 12.8.7 (described below):
- The default value (and only value in standard mode) for the minimum level
1-3 sky cover necessary to allow external-model-based precipitation was changed
from the previous 40% to 20%.
- The minimum 12-hour precipitation probabilities for "possible"
and "likely" thunder have been changed from 15% and 25%, to 10%
and 20%, respectively, thus making appearance of thunder slightly more likely
in the plain text output. This would be most noticeable for precipation probabilities
between 10 and 15%, where the former "Precipitation showery or intermittent"
wording will change to "Scattered thundershowers possible".
- In wret.exe, the number of decimal places for precipitation rate and total
precipitation has been reduced in the case of large numbers (i.e. 100 mm or
more) which would run into other columns if the original decimal places were
- In wret.exe, horizontal visibility's units are now dependent on the temperature
unit choice instead of the previous thickness unit choice. When Fahrenheit
is in use, visibility units are now miles; with Celsius, they are in kilometers.
Also, if the visibility (in either unit system) has a value less than 10,
one decimal place will be displayed. (Previously it was a whole number in
- In wret.exe, you may now check up to 15 temperature items and 15 'other
data' items. As before, only the first 5 of each will be displayed on the
screen, but the entire set will appear in lastret.txt. Also, some minor formatting
changes were made in lastret.txt, to remove some of the excess spaces when
fewer than the maximum number of items are selected.
- In wret.exe, two new temperature values were added: the maximum and minimum
temperatures from which daily max and min values are obtained. Around the
time of the maximum, the difference between the new max value and the most
likely 1.5 meter temperature (the main forecast value) is an indication of
the amplitude of the largest short-term fluctuations likely (though the new
min value at the time of the max is less meaningful, and often a bit warmer
than the lowest temperature due to short-term fluctuations). Around the time
of the daily minimum, the difference between the new min value and the 'main'
temperature indicates fluctuation amplitude, with the max value a bit less
meaningful. In short, these are simply values from which daily max and min
temperatures can be extracted.
- In both WXSIM and wret.exe, the upper end of the convective sensitivity
adjustment has been extended to +2 instead of the previous +1.
- In both WXSIM and wret.exe, minor cosmetic changes and changes to the help
file were made.
- In both WXSIM and wret.exe, summaries at the end of the text display now
show 24-hour max and min temperatures to the nearest tenth of a degree, instead
of the previous whole degree. This should not be understood as a claim of
higher accuracy, but the decimal places might be interesting for comparisons
or identifying trends in the program's behavior.
- In wret.exe, after the message that too many temperatures (or 'other data')
options are checked, the program will automatixcally uncheck the last item
you check, thus preventing errors that would occur if you proceeded without
heeding the message.
- This item was actually present in 12.8.7, but I forgot to list it below:
A check box on the Auto Run form allows you to have the date listed along
with the day of the week in the plain text output.
- Numerous improvements and additions were made to the agricultural module.
Soil moisture is now reported in soil moisture tension as well as percent
by volume, with these being functions of each other as well as of soil type.
Both soil moisture and temperature can now be imported (via WXSIMATE Version
5.0) from either WeatherLink (for up to 5 depths) or Weather Display (for
one depth, and possibly more in some later version), and this can work in
auto mode as well as manually. Irrigation can now be planned on the Interrupt
Planner, and this, along with soil moisture tension, can be plotted in wret.exe
as well as output in WXSIM itself.
- Several small cosmetic, organizational, and wording changes were made in
- An occasionally encountered bug producing a "division by zero "
error has been corrected. This problem most likely occurred only if local
calibration data was being used, and required a rather special set of circumstances,
so that it was sporadic in nature.
- In addition to the changes listed in (12), the algorithm for the default
soil moisture (as a function of location, season, and recent precipitation)
has been improved considerably.
- In wret.exe, a bug - which caused text and lastret.txt display of all soil
moistures to be that at depth 1 - has been corrected.
- Bugs which could cause division by zero or invalid property value problems
were fixed. These were associated with interpretation of local station calibration
data in localcal.txt.
- Output format of certain variables to lastret.exe in wret.exe, such as severe
weather indices, was changed so that values of -10 or more negative are rounded
off to whole numbers, so that columns of data won't run together.
Version 12.8.7 (June 10, 2011) had the following change relative to Version
12.8.6 (described below):
- The results of a recent careful study on thunderstorm activity as a function
of various stability parameters (especially the K and Total Totals indices)
using many U.S. surface and upper air sites' historical data (spanning up
to 25 years) - combined with information from two large studies in Europe
(Germany and the Netherlands) was used to substantially improve WXSIM's convective
bulletins. A very thorough description of this improved algorithm is now included
in this manual.
- Slight changes were made in the wording of convective bulletins. Also, the
following plain text convective output now consists of:
" Precipitation showery or intermittent."
" Scattered showers possible."
" Scattered thundershowers possible."
" Scattered thunderstorms likely."
" Scattered thunderstorms likely, some possibly severe."
" Thunderstorms very likely, some possibly severe."
" Thunderstorms very likely, some severe."
" Severe thunderstorms likely, with possible tornados."
These were removed:
" Thunderstorms likely, some severe."
" High risk of severe thunderstorms and possible tornados."
- The plain text convective bulletins now take into account thresholds of
12 hour probability of precipitation. This helps screen out occasional contradictory
information (such as thunderstorms "likely" when rain chances are
below 20%), though it may cause some inconsistency with the scrolling convective
bulletins, most likely in that a few convective bulletins may be more aggressive
than the final plain text output. If this is found to occur frequently, a
small downward adjustment in the convective sensitivity may be in order, since
the final plain text forecast incorporates a bit more information than do
- The automatic level 2 cloud cover minimum of 60% during precipitation has
been reduced to 45%. This could increase temperatures very slightly on afternoons
with light shower activity, but a recommended slight change in the GFS temperature
and cloud cover bias (see #6, below) may just about exactly cancel this out
- A major review and readjustment of the routines for finding heights and
thicknesses of the various pressure levels was conducted. The changes made
include updating the virtual temperature calculation to an official published
equation (previously it was a fairly good, empirical one I had developed),
including level 3 and 4 relative humidity values (values up through level
2 were already incorporated, but above that default values had been used),
establishing new ways of averaging the limited temperature data to best characterize
layer average values, and (importantly) removing an altitude-based correction
to the acceleration due to gravity, so it is now a constant 9.80665 m/s/s,
as appears to be standard for the geopotential (as opposed to geometric) heights
that are standard in imported model data.
- A thorough review of GFS temperature verification results, from this site:
- strongly suggests that a cold bias which existed a few years ago has been
largely corrected. For this reason, the default value for the upper level
temperature bias correction has been changed from 0.5 to 0 (professional version
users will need to change this manually, but the change will be automatic
for standard version users). Also, verification results from about 1200 forecasts
over the last year here in Atlanta suggest that GFS biases in cloud cover
and precipitation (a previous year of data had suggested the model was too
cloudy and wet) have also largely disappeared, so the bias correction setting
for cloud cover, precipitation intensity, and precipitation intensity skew
have been changed from the previous -3, 90, and 2, to -1, 95, and 1, respectively.
This will generally increase cloud cover by about 4% and precipitation by
about 5%. Professional mode users should consider their own accumulated experience
as local effects can be important here.
- More thorough data on 700 mb relative humidity in WXSIM was made accessible
- The forest effect on snow cover was increased somewhat.
- A bug in wret.exe that caused values of UV index to be too high was corrected.
- In light of new data, the UV index algorithms in WXSIM was revised generally
downward by about 7 or 8 percent, and the elevation effect part of this was
- The UV index algorithm used for display on the main Data Entry form of WXSIM
was found not to be consistent with the one used in the output. These two
instances of UV index now share a common algorithm.
- An option was added in wret.exe to include a numerical convective parameter
in the lastret.txt file (created when 'View Text' is selected).
- The default dew point depressions, as functions of layer cloud cover, were
changed for levels 2 through 5. In particular, cloud cover of less than 10%
now gives dew point depressions tending towards 14, 18, 16, and 15 degrees
Celsius for levels 2 through 5 respectively. This was based on averages of
all soundings from Athens, Georgia, for days with less than 10% average total
cloud cover, over a 6 year period.
- A new setting was added to the Local Data Import form, allowing specification
of a minimum sun altitude (default 10 degrees) for using estimated cloud and
haze data from WXSIMATE. This is useful because low sun angles yield relatively
unreliable solar-radiation-based cloud and haze estimates. The setting specifically
refers to sun altitude 30 minutes before the forecast initialization time,
because the default time span used in WXSIMATE (for collecting solar radiation
data for this purpose) is the hour leading up to the forecast time.
- A new setting on tab 4 of the Preferences/Settings form allows specification
of a threshold value for combined level 1 through 3 cloud cover (in percent),
below which precipitation will not be forecast, even if present in FOUS data
or on the Interrupt Planner. This is probably most useful in cases where the
orographic downslope effect is in use; the reduced cloud cover in such cases
may well be accompanied by an elimination of precipitation. The default value
(and only value for standard mode) is now 40%. If precipitation was previously
supposed to be forecast at a certain time, a small increase in cloud cover
may be observed in the forecast as a vestige of what would otherwise have
- The 'Reduce superadiabatic' feature was modified by weakening the effect
slightly, so that even with it active, the near-surface temperature lapse
rate will be allowed to exceed dry adiabatic by a slight amount - and by slightly
more than before.
- The 'enhanced maritime effect' was expanded to include a reduction in the
cooling effect of precipitation, considering the fact that the nearby or surrounding
sea is not made any more wet by rain falling on it, and thus removing a component
of evaporative cooling that would exist for an inland site.
- A protection was added against a very rarely encountered report of freezing
rain with temperatures well above freezing.
Version 12.8.6 (March 11, 2011) had the following change relative to Version
12.8.5 (described below):
- A protection in wret.exe, against trying 'comparison to actuals' or 'auto
select' when more than 5 items are checked in either the 'temperature and
thicknesses' or the 'other data' section, has been changed to allow up to
10 items, which is the maximum anyway (5 of which would show only in lastret.exe).
Previously, if such a run was attempted with more than 5 items checked, the
program simply did nothing. Now it will complete the requested task.
- A safeguard was added in wret.exe against a 'division by zero' error during
an 'auto select' run, in the rare case that the average departures from normal
of the warmer and colder halves of the data points are identical. Now such
an occurrence will simply generate a slope of zero for the temperature error
as a function of departure from normal.
- A new feature was added to Preferences/Settings, allowing the user to specify
a description the density of forest (especially evergreen) in the surrounding
area, for modification of the effect of snow cover. Some consideration had
been given to this already, in the form of a ground cover parameter included
in the customization. However, this appears not to have been sufficient for
describing situations such as dense fir forest in high northern latitudes,
where the dark trees considerably mitigate the cooling effect of the otherwise
high albedo (reflectance) snow cover. Any setting entered by the user is saved
- A small problem with snow:water ratio as used during the calibration run
was corrected (it had defaulted to a value of 2 in most cases). This change
will have only a very small effect on forecasts.
Version 12.8.5 (February 19, 2011) had the following change relative to Version
12.8.4 (described below):
- A sophisticated and carefully researched new algorithm replaces the former
one for estimating wind gusts. The new routine takes into account the user's
choice of definition of gusts (i.e. higest wind in a 10 minute period, versus
highest in a 60 minute period) and allows adjustment of gust factors by the
user, who can also specify the lowest speed wind gust to be reported in the
plain text output.
- A caption, just under the site information on the Data Entry form, now displays
whether professional mode is OFF or ON, and whether auto run is OFF or ON.
- A bug, which caused small errors in the drawing of the upwind direction
(thick arrow and dotted curve) on the advection sites map, has been corrected.
This would mainly have been noticed in manual mode (or in auto run if you
were watching very closely) and different flow curvatures were being tried.
It did not affect auto run forecasts, but could have influenced user decisions
when experimenting with flow curvature choices manually.
- A bug, which could cause the program to get into an endless loop of saying
"Calibration Run" if the cor.txt file was corrupt, has been fixed.
Now, such corrupt files (how it got corrupted is yet to be determined) will
be identified as such, the user will be notified by a message box, and the
run will be allowed to complete, using default correction factors of 0, 1,
0, and 0. At the same time, a more centralized error trapping method was instituted,
to hopefully make identifying any future run time errors easier.
- A protection was added to guard against unrealistic wind values that could
result if either the localcal.txt or localdat.txt files were somehow corrupted
during or after an import of local station data using WXSIMATE. This protection
was added in response to the only reported case of the problem, which produced
a brief period of abnormally strong winds.
- A bug, which could cause an 'invalid property value' error if the Stop AM
Rain refinement was chosen, has been fixed. The error probably appeared mainly
in the winter season, and this is a summer season feature, which is probably
why the bug took so long to show up. Note that this feature boots up with
default times, except in auto run, where the settings are remembered from
the last run.
- Wind chill wording was changed to include both the lowest and highest values
of each 12 hour forecast period (when colder than a threshold of -3 C), with
the term "ranging from
- The snow remembering routine was changed to avoid errors which could occur
with certain Windows regional settings which use decimal separators other
than periods. If the old format is encountered, a message will alert the user
to this fact, with instructions to temporarily disable the routine to let
a new forecast run, at which point it can be re-enabled.
- Wind gusts over 1 and 10 minute and 1 and 6 hour periods were added to the
display options in the retrieval module (wret.exe).
- A bug (which may have existed for many years) involving wind chill in wret.exe
was corrected. This bug had caused erroneous graphical and text display of
wind chill values when wind speed units were other than miles per hour.
- Now up to 10 items from the temperature-related options, and also 10 from
the 'other' data options, can be chosen in wret.exe. Only 5 from each group
can be displayed as text or plots, but the others will appear in the lastret.txt
file. If you do choose more than 5, the program will decide which 5 to display,
as currently there is no mechanism for making this specification.
- Choices for data to display in wret.exe have been rearranged into more logical
- Protection in the form of a message box (manual mode only) and reasonable
default values was added for extreme wind speeds from potential misinterpretation
of METAR or other ingested wind data.
- Megajoules per square meter were added (to Watt x hours per square meter
and Langleys) as an option (under Preferences/Solar Energy Units) for output
total daily solar radiation. A similar addition was made to wret.exe (the
- Precipitation and total solar radiation units were added to the hard copy
printouts available for Plots in wret.exe.
Version 12.8.4 (January 11, 2011) had the following changes relative to Version
12.8.3 (described below):
- A bug, discovered in the 'snow remembering' routine just introduced, has
- The formatting of the snow depth box on the snow/ice entry form has been
changed to round off to the nearest hundredth (this change prompted by the
appearance of decimal values in this form in some cases after use of the 'snow
Version 12.8.3 (January 11, 2011) had the following changes relative to Version
12.8.2 (described below):
- Further testing of item #7 for 12.8.2, below showed errors in the normal
diurnal range of some sites. This turned out to be due to mathematical errors
out in about the 12th digit, perhaps due to to the precision and type of the
variables involved. Normally such a problem would be trivial, but a condition
(whether or not the variable's value was exactly zero) that had been set made
the effect much larger. This has been corrected with a protection against
the resulting extreme values. Now both old customizations and future ones
should function properly.
Version 12.8.2 (January 10, 2011) had the following changes relative to Version
12.8.1 (described below):
- The tolerance for triggering a message about sea surface temperature being
out of range was increased from 2 Celsius degrees (3.6 Fahrenheit degrees)
to 3 C (5.4 F).
- A typo ("Relativelymild") in the plain text output was corrected.
Also, freezing rain wording for metric units had "above ground"
added, for consistency with imperial units.
- Wind chill during the daytime periods in the plain text forecast was changed
to reflect the *warmest* value during the day, with wording such as "Wind
chill colder than
- The (somewhat rarely used) READY data turns out to have changed format slightly
at some point, which led to WXSIM omitting precipitation while parsing. This
has been corrected, and simultaneously, arrays have been expanded to handle
the 3-hourly READY data out to 192 (instead of the previous 180) hours.
- A bug (starting with Version 12.8.1), which kept wret.exe from recognizing
old correction factors in forecasts, has been corrected.
- Start and ending times for the forecast run itself were added to the latest.txt
(and archived versions) file.
- A parameter has been added for future customizations that will permit slightly
better matching of some sites' climatological diurnal temperature ranges (thus
affecting displayed normal max and min temperatures).
- A bug (discovered as I was testing (7), above), which allowed inaccuracies
of perhaps a degree or two in the displayed normal max and min temperatures
(by not fully determining the normal diurnal range as intended) has been corrected.
This has virtually no effect on forecasts and had only a very slight effect
on the quality of some customizations. Earlier customizations affected by
this will now show more accurate climatological temperature data.
- Top layer (the top one centimeter) soil temperatures are now initialized
more accurately due to improved interpolation and extrapolation algorithms.
- A new parameter, called 'Base insulating effect', has been added to the
soil data form. The need for this arose as I did additional testing on both
summer and winter soil temperatures in various scenarios, using data from
the Soil Climate Analysis System (SCAN). This appears needed to represent
thermal effects (mostly simple insulation, I believe) apparently due to grass
turf ground cover. It should probably be set to zero for truly bare ground,
but otherwise, values around 2 seem about right for a wide range of conditions.
- A option to 'Initialze with previously forecast snow cover' (on the first
'tab' of the Preferences/Settings form) has been added. This allows WXSIM
to start a new forecast using the snow cover from the last forecast run, specific
to the date and time of the new forecast. You can still override this by entering
the new snow cover directly, but this feature will be very useful if you must
be away from the computer during a series of forecasts where snow is accumulating
and/or melting. In this case, the snow/ice cover refinement does not need
to be active (hightlighted red), though is may be.
Version 12.8.1 (December 30, 2010) had the following changes relative to Version
12.8 (described below):
- The interface for many of the settings was considerably rearranged, by creating
a new form, under a new item called 'Settings' (under Preferences on the main
menu bar). On this form is a combination of the former text width form, the
minimum UV and precip form, the fog and frost options form, and the model
bias form. Some items from the Interrupt Planner were also duplicated for
easy access, especially for users doing mainly auto runs.
- Sliders were added (to the form in (1), above - professional mode only)
to control the strength of the 'allow decoupling' and 'additional maritime
- Site and date specific temperature variation data has been added to this
- The ability to specify upslope, downslope, and lake-effect directions for
wind has been added. These features, available only in professional mode,
can alter cloud cover and precipitation amounts derived from imported model
data in order to model effects on a scale smaller than that of the model (mainly
GFS) data. Proper use of this feature will require study on the part of the
user over time, and controls are provided to allow the user to tweak these
settings based on accumulated experience.
- Optional wind and temperature descriptors have been added for the plain
text output. The wind part is fairly straightforward ("breezy" for
>12 mph, "windy" for >17, and "very windy" for >25).
The temperature part is very sophisticated, taking into account not only actual
temperature, but also wind chill values and number of standard deviations
from normal specific to the site and date.
- Wording rules for precipitation in the plain text output have been changed
so that probablilities or amounts will not be mentioned unless there is a
specific reference to precipitation or at least a chance of convection in
- Changes were made to wxsim.exe which now allow use of newly created (using
wret.exe) bias correction factors without having to restart WXSIM.
- Changes were made in wret.exe so that, if the "learning" option
is turned off in WXSIM, the effective correction factors for those forecasts
will be considered to be the default values.
- Protections (in the form of message boxes) were added to wret.exe so that
users are much less likely to take an incorrect sequence of actions which
might have led to an error.
- A bug, which could occasionally carry over precipitation from the end of
one forecast to the first line of text of the next, has been corrected.
- A possible 'Invalid property value' error when using imported precipitation
data has been averted.
- An oversight which on rare occasions could allow METAR reports of runway
condition to be misread as temperature and dew point (possibly leading to
'dew point cannot exceed temperature' message) has been fixed.
- Another METAR import bug which could also very rarely lead to a dew point
being read as a barometric pressure (hence triggering an 'unrealistc barometric
pressure' message) has been fixed.
Version 12.8 (November 30, 2010) had the following changes relative to Version
12.7.5 (described below):
- A new suite of calculations of agricultural interest, such as soil temperature
and moisture, and evapotranspiration, was implemented, and is available in
professional mode. A new menu item in the main program was added to accommodate
user defined choices of output. These new output variables (23 in all) can
also be viewed as plots or text in the retrieval module (wret.exe). Further
refinements and features can be expected in upcoming versions.
- A message box which was new to Version 12.7.5, but which I forgot to document
below, was causing problems for some users. This message was intended to detect
if another version of WXSIM was open, and alert the user to that fact. In
some cases, the message appeared inappropriately and interfered with auto
runs. This "new" feature has now been removed, as it may have caused
more problems than it avoided.
- Two problems with temperature forecasts for island, coastal, or near coastal
areas were addressed (a typical, but not unique problem region being New Zealand).
One is that of too-high maximum temperature forecasts, mainly in spring. The
other is that of too-warm minimum temperature forecasts on calm clear nights,
just about any time of year, but perhaps most prominently in winter. The first
problem was identified as an inappropriate lack of marine influence when winds
were from the "inland" direction, especially when water is not too
far in the direction (as on an island). The solution is an optional sea-breeze-like
influence (but without modification of wind), which can operate either with
or without the existing sea breeze routine (the effects are roughly additive).
The other problem was addressed by increasing the effects of the existing
'allow decoupling' routine (check box on the Interrupt Planner), using an
additional component to the routine which specifically increases diurnal temperature
range. Both of these routines are influences by a new input on the form reached
by selecting 'Min UV and Precip, Sea Breeze, and Advection item under parameters.
This new item lets you define a distance to the far side of an island or peninsula,
up to 100 miles (161 km) distant.
- A significant problem with the "learning" routine ('auto select')
in wret.exe was discovered and corrected. This was actually making forecasts
*worse* for some users. It manifested in the slope of the error versus departure
from normal line. The earlier "correction" was exactly backwards,
and either made too-extreme forecasts more extreme, or too-moderate forecasts
even more moderate (in terms of departure from normal seasonal mean temperature).
One indication of the problem was frequent appearance of a message that the
slope correction was 'out of range' and would be 'limited' (which is a good
thing, as the limitation kept the problem from getting too far out of hand.
- A number of cosmetic and display changes were made in wret.exe, including
the addition of mean temperature of a forecast period on the graph showing
temperature errors versus day of forecast. Also, the "proposed"
line on the graph of temperature error versus departure from normal now has
a more clear meaning. It now shows the correction that will be made in practice
if the proposed values are accepted.
- The text width scroll bars in both wxsim.exe and wret.exe were given greater
ranges, in order to accommodate different font sizes and resolutions that
may be available with newer versions of Windows.
- On the Text Width, Heat Index, and Frost Options form (under Parameters),
users can specify a choice of conditions under which to display frost as an
output in the plain text output. This includes an option to mention frost
only if it is "climatologically significant", meaning unusual enough
for the season to be "newsworthy". This decision is guided by WXSIM's
own internal estimate of the climatological probability of ground frost occurring
on the current date. NOTE - This feature has already been present since about
Version 12.7.2, but I forgot to describe it sufficiently before. ANOTHER NOTE
- I have become aware that, in many countries "frost" refers speficically
to the occurrence of freezing temperatures. This is NOT the meaning in WXSIM,
where it instead refers to a form of condensation (more properly, "deposition")
of water ice onto surfaces like grass or cars. "Heavy" frost, here,
means a lot of the white stuff, not necessarily especially low temperatures.
Version 12.7.5 (July 2, 2010) had the following changes relative to Version
12.7.4 (described below):
- Changes were made to the plain text output decision algorithm, mainly to
prevent mention of precipitation chances below 20 percent when the 'Omit trace
amounts or very slight chances of precipitation' box is checked. This is actually
a second attempt at the fix in 12.7.3, which still had a loophole and was
not fully successful.
- A bug was discovered in the sea breeze routine, in which it wrongly used
north as a default water direction when reactivated during auto run. This
has been fixed, as was a closely related problem involving the mountain/valley
breeze routine, where is had been 'forgetting' the diurnal breeze amplitude.
- The Diurnal Breeze form (containing both the sea breeze and mountain/valley
breeze controls) now had a 'Reset Defaults' button, which if clicked populates
the form with the originally customized data, including current seasonal sea
surface temperature (adjusted to site level, as always, with a lapse rate
of about 3.5 degrees F per 1000 feet or 6.5 degrees C per kilometer).
- There is now a message box which warns the user if, in auto run, the retrieved
(at boot up) water temperature is different from the default climatological
value by more than 4.5 degrees F (2.5 degrees C). This si intended to prevent
the problem of unseasonal default water temperatures being used in the forecast
when users do not reset the value reasonably often.
- A very small bug, which could make temperature forecasts on subsequent runs
using identical data different by perhaps a couple tenths of a degree, has
been fixed. It was due to an inconsistency in how the 'air mass temperature'
was determined the first time through, versus on subsequent runs.
Version 12.7.4 (July 1, 2010) had the following change relative to Version
12.7.3 (described below):
- Change #3 under Version 12.7.2 (below) was discovered to cause an occasional
error #5 (invalid procedure call or argument). This has been corrected, while
preserving the new parsing ability introduced in Version 12.7.2.
Version 12.7.3 (July 1, 2010) had the following change relative to Version
12.7.2 (described below):
- A change in the plain text output algorithm, introduced in 12.7.2, caused
a change in the output in the case of using the 'Omit trace amounts or very
slight chances of precipitation' box on the 'Minimum UV Index and Precipitation
for Display, etc.' box. It should now behave as before.
Version 12.7.2 was completed on June 29, 2010 and has the following changes
relative to Version 12.7.1 (described below):
- An isolated instance of failure to recognize commas as potential decimal
separators (in certain Windows regional settings) was corrected.
- An option (mainly for Canadian users) to use humidex instead of heat index
was added, and can be accessed under Preferences on the same form as text
width. Humidex was also added to wret.exe's optional outputs.
- METAR barometric pressures failing to use standard prefixes ("A",
"SLP", or "Q") are now read anyway. Also a default pressure
of 29.92 inches of mercury (1013.2 millibars or hectopascals) is now assumed
at the beginning of METAR import in case no pressure reading is found.
- WXSIM now detects other open copies in the same folder, or instances of
failure to close the program properly, and alerts the user to this with the
choice to proceed or quit (and perhaps either use or close any other open
- WXSIM now optionally includes frost descriptions in the nighttime forecast
- The frost decision routine was modified using additional data, including
information on the difference between 'grass' temperature (within 10 cm of
the surface) and 1.5 meter "shelter temperature", from http://www.knmi.nl/publications/fulltexts/hisklim7.pdf.
- The plain text output (saved as plaintext.txt and also incorporated in some
other products) now includes (optionally, if Convective Bulletins are enabled
under Preferences) mention of showers, thunder, or severe weather if WXSIM
considers the probability sufficiently high, even if imported model data doesn't
suggest measurable precipitation.
- A new option, activated by checking the new 'Allow decoupling' box on the
Interrupt Planner form, permits WXSIM to decrease both maritime temperature-moderating
influence and the strength of warm air advection when the strength of (mainly
nocturnal) temperature inversions exceeds a certain, rather weak, threshold
value. This effect increases with the strength of the inversion and is therefore
strongest on clear, calm nights. It is most significant in coastal and near-coastal
areas and its main effect is to lower nighttime low temperature forecasts.
This change was motivated by reports of too-warm overnight lows, mainly in
coastal areas, under clear conditions with light winds.
- Made minor cosmetic and help files changes.
Version 12.7.1 (February 20, 2010) had the following changes relative to Version
12.7 (described below):
- Provided error handling in case a printer is not declared. Now, a message
will appear explaining the need to do so, along with instructions for how
to do so in control Panel.
- Fixed a bug which could cause errors in the station precipitation amount
in Comparison's in wret.exe for users of Weather Display
- Made minor cosmetic changes.
Version 12.7 (February 15, 2010) had the following changes relative to Version
12.6.3 (described below):
- A 'subscript out of range' error that could have occurred when importing
GFS data that is initialized after the forecast (which can happen only if
you are running forecasts after the fact) has been averted.
- Another 'subscript out of range' error that could have occurred when importing
GFS advection data for a different site has been averted. A message box will
now appear alerting the user to import fresh GFS advection data relevant to
the current site.
- The optional GFS temperature and dew point plots on the Output form's graph
now have correct colors for the current background color (an earlier coding
problem had led to low-contrast displays).
- Thunder and severe convection outputs (the same ones displayable in wret.exe)
are now written to the main (not 'daily') .csv output file. Column headings
help describe these roughly 0-5 scales.
- An option has been added to the Auto Run form to execute a user-defined
DOS batch file after auto runs or after the user clicks 'Repeat' after a manual
run. Possible uses might include converting a .bmp file to a more compact
format (like .png) using another program, uploading files to the internet,
or a combination of such actions. A sample batch file, called latestbmppng.bat,
is provided in the demo package to instruct IrfanView Version 3.2 (see www.irfanview.com
if you are interested in obtaining this program) to convert the optionally
produced graphic latest.bmp to latest.png in the c:\wxsim folder.
- An option has been added (to the Minimum UV Index and Precip form) to adjust
the effectiveness of diurnal breezes (sea breeze or mountain-valley breeze).
This affects the diurnal wind vector component and also (in the case of sea
breeze) the direct effect on temperature. It is strongly recommended that
users research their forecast bias histories before considering any such alterations.
- Another option added to the above form adjusts the effectiveness of cold
or warm advection. It is strongly recommended that users research their forecast
bias histories before considering any such alterations. The only locations
I know of at present that seem to warrantthis intervention are in southern
- Various cosmetic changes were made, including adding program-specific icons
to the forms in both wxsim.exe and wret.exe, and changing the background color
of the help forms in both programs from yellow to a less harsh tannish-orange.
- Changes were made to the vertical lines on both the regular and comparison
plots in wret.exe. On the regular plots, the bright blue vertical lines (which
did not consistently mark days) were made a darker blue, and with other dark
blue lines form an unobtrusive finer scale (easily interpreted only when showing
2,3,4,6, or 8 days) than the gray lines marking midnights. The comparison
plots' blue lines were removed and, instead, the dark gray lines now show
midnights while the light gray lines show every six hours.
- The fog sensitivity wording was changed to put the default value of 45
(instead of the previous 50) in the middle of the 'normal' range. Also, the
description is now highlighted in red if it is outside the range of 'low-normal'
to 'high-normal'. Similar behavior was also built in to the new diurnal breeze
and advection adjustments, (6) and (7), above.
Version 12.6.3 (November 22, 2009) had the following changes relative to Version
12.6.2 (described below):
- A change was made to avoid an 'input past end of file' error (#62) when
WXSIM tries to access GFS data for advection, and it's not present. This error
generally occurred if the 'GFS for advection' box in WXSIMATE was not checked
(it generally should be checked, as this is a valuable source of data for
most users). Now the program should silently close the file with missing data
without producing an error.
- A cosmetic error introduced accidentally in 12.6.2 (the 2 PM check box on
the auto run form had been shifted in front of the 1 PM check box, rendering
the latter invisible) has been fixed.
Version 12.6.2 (November 21, 2009) had the following changes relative to Version
12.6.1 (described below):
- The ~Monotone check box on the advection form was replaced by
a Mono scroll bar which allows mixing of the monotone and not
monotone fits in various ratios, from 0% monotone to 100% monotone (in increments
of 10%). The default value is 50%, which is generally a good compromise between
getting the closest fit to the data points and avoiding unrealistic extrapolations.
This setting is not saved. The 50% default is also used in auto run, unless
Enforce monotone is checked on the auto run form, or there is
a strong inversion. In these cases, the fit will be 100% monotone, meaning
the advection profiles for temperature and dew point will not have any slope
- The GFS advection data across longitude 180 degrees (see #1 below) is now
active on Chris McMahons site, and the feature is now fully operational.
Version 12.6.1 (November 14, 2009) had the following changes relative to Version
12.6 (described below):
- Support was added for advection across longitude 180 degrees (such as in
New Zealand with winds from the east), in anticipation of expanded coverage
in the GFS files for advection produced by Chris McMahon.
- Colors were changed for the temperature and dew point displayed by the 'Show
GFS' button on the Output form. Previously (by mistake) they were not matched
properly with the blue or gray backgrounds of the graph. They now will be
displayed with the same colors as WXSIM's forecast values, but with thicker
- A scale was added for the wind speed arrows on the advection data maps.
- Minor informational and cosmetic changes were made to the Auto Run form.
Version 12.6 (September 19, 2009) had the following changes relative to Version
12.5.4 (described below):
- Support was added for a new set of GFS data kindly downloaded and culled
by Chris McMahon. This is GFS data, but now for a 20 x 20 degree grid surrounding
the home site, so that GFS may now be used for advection data, both initially
and after wind shifts. This feature should be especially useful for users
outside North America (since they do not have MOS for after wind shifts),
but also for North American users more than 2 or 3 days into a forecast, when
MOS runs out. It will also be helpful for users on islands or near coastlines,
as data from ocean locations will be available (the extent depending on my
original allotment of surface advection sites in the customization).
- GFS data can be used to fill out the main Data Entry form values, with most
of it coming from the new data set, except for barometric pressure, which
uses the previously existing set. This is not the best way to fill out this
form, since local METAR, synoptic, or home station data would be more timely
and accurate. However, for remote sites with no surface data available, this
should initialize the program well enough for a good forecast in most cases.
- A time series of GFS temperature and dew point data is now extracted, and
can be displayed by clicking the new 'Show GFS' button on the Output form.
This makes an interesting, direct comparison with WXSIM's own forecast on
the Output form's graph.
- Internal changes in the auto run routine were made, which may reduce or
eliminate the possibility of certain errors (especially number 52, 'Bad file
name or number'). This change avoids opening the FOUS and RAOB data display
forms, which should keep things simpler for Windows as it tries to thread
the actions properly.
- A warning was added to all the options under the Start menu to prevent users
from starting a new forecast without clearing the Ouput form from a prior
run. This eliminates one possible cause of Error #52 (see above).
- A new, very small form consisting of a progress bar and percentage figure
(appearing in the lower left part of the screen, just above theWindows 'Start'
button) has been added, to display the percentage of the forecast complete
so far, as it runs.
- There is now an option to 'Minimize forms' on the Auto Run form. This causes
almost all forms to be minimized during auto runs. The exceptions are the
small progress bar form (see above), the file import progress bar form (which
appears intermittently, and in this case is moved to the lower left part of
the screen, just above the new progress bar form). And - in the case of 'Run
Immediately' - the Data Entry form. In a scheduled auto run, Data Entry will
start out minimized if the program just booted, and will otherwise remain
minimized once it has been manually minimized. These changes should enable
users to perform other tasks on the computer while WXSIM runs, with only minimal
- Choice of surface data source (METAR, SYNOP, or GFS) is now saved only after
import of data for the home site, and no longer after advection data imports.
The reason for this is the complexity of choices now that all these (plus
MOS) are now supported.
- The retrieval program wret.exe now checks for completeness of the initialization
file retini.txt to trap errors resulting from damage (which a few users have
seen, though the cause is at present not known). If damage (usually missing
lines) is detected, wret.exe displays an error message to that effect and
then attempts to restore the file using a backup file, retinibak.txt, which
in turn is created as a copy of retini.txt if the latter is not damaged. Therefore,
just one successful load of the program is sufficient to establish the backup
file. Meanwhile, a copy of any damaged retini.txt file is saved as retinibad.txt.
- A new check box, 'Close program after auto run', has been added to the Auto
Run form. If checked, this will cause the program to shut down right after
the run is finished. The intention here is to save users, who use System Scheduler
(or similar) to open the program, the trouble of also using such an external
program to close WXSIM.
- Changes were made to wret.txt to allow comparison of precipitation forecast
to actual values, and also to include averages as well as maximum and minimum
values in the analysis of this plus existing items. NOTE: In order to analyze
precipitation for past forecasts, WeatherLink users will need to run Import
Data in WXSIMATE for all past months for which analysis is desired. This is
best done by manually entering a date (make sure the Scheduler is OFF) early
in the *following* month so that a file will be created for the entire previous
(desired) month. Start in the past and work forward one month at a time. After
this, the latest two monthly files will be updated (including precipitation)
every time Import Data is run, so no further corrective actions will be needed.
- A small cosmetic change was made to allow better readability of weather
types in the saved bitmap plots in wret.exe.
- In wret.exe, the default directory for the WXSIMATE-derived VWS and WeatherLink
data files is now forced to the current (boot-up) directory of wret.exe for
using the Comparison feature. This was already almost the case, but there
was a loophole that might have allowed the path name to change in some cases
of analyzing forecasts in other directories. The forecasts may be located
wherever you like, but wxsim.exe, wret.exe, and wxsimate.exe must all be located
in the same folder (usually c:\wxsim).
- Capacity for number of combined forecasts in 'Compare to Actuals' in wret.exe
has been increased from 999 to 9999.
- A bug that could allow a 'File already open' error in wret.exe - when changing
weather station software types and/or directories in wret.exe for Compare
to Actuals - has been fixed.
- Changes were made in wret.exe to allow proper display and use of certain
items which may have been affected by regional and language setting in Windows
which use commas as a decimal separator. There now should be no problems in
the program related to this.
- A change was made in WXSIM to hopefully preclude the possibility of a #Nul#
value appearing for the diurnal range multiplier in the .wxf files.
- A change was made to allow a tolerance of 1 in either direction on 6 digit
WXSIM registration codes, due to an apparent computational uncertainty in
the encryption algorithm.
- Changes were made to avoid errors in case certain small, optional files
skiplog.txt) exist but are empty.
- Clarified language on Auto Compare form in the Retrieval Module
- A safeguard was added to prevent an error which could have occurred while
using GFS advection data.
- Specified that the 'Retrieval Module (wret.exe) not found' error message
really require that error code instead of assuming that this was the only
such error that could occur.
Version 12.5.4 (July 8, 2009) had the following changes relative to Version
12.5.3 (described below):
- A bug which could occur after pressing 'Start Fresh' on the Output form
has been fixed.
- Options were added to the Auto Run form, allowing omission of either the
log files (log.txt and latestlog.txt) or the comma separated variable files
(latest.csv and latestdaily.csv), or both, from the forecast run. These files
are not essential to operation and their accessing (mainly in auto mode) may
trigger sporadic 'Bad file name or number' errors (#52) on certain computers.
The reason for this is not clear, but may be associated with having a number
of other programs (perhaps especially Terminate Stay Resident, or "TSR"
programs) active. If you encounter such errors, checking one or both of these
new boxes may solve the problem.
- The wording of the command buttons has been altered slightly to be more
descriptive, and the (new wording) 'Disable Auto Run But Keep Settings' button
now allows any changes you made to settings to be saved, both within the current
session and on exit, for later boot-ups.
- The 'Activate scheduler on next boot up' option now not only "sticks"
(as it did before) upon leaving the Auto Run form, but also "stays stuck"
when the Auto Run form is reactivated.
Version 12.5.3 (June 29, 2009) had the following changes relative to Version
12.5.2 (described below):
- A bug, which caused the program to stall if both the 'skip this screen'
and 'start scheduler on next bootup' options were check, has been fixed.
Version 12.5.2 (June 25, 2009) had the following changes relative to Version
12.5.1 (described below):
- There is now a search option in the On-File Sites form, to locate a desired
site by METAR, Name, State, or Country. This is mainly for the me (the author)
so that I can more quickly find sites in my list of over 600. It may also
be somewhat useful for the few users who have several sites.
- The data is now read using separate commands for month, day, and year, so
that more date formats should now be supported. The two options for display
are still MM/DD/YY and DD/MM/YY. (This change was actually implemented in
12.5.1, but I forgot to include it in the list below)
- There is now an option to archive forecast files in a directory other than
that of the main program. You must first create the folder. Then, after running
a WXSIM forecast, click Save. Then, on the form that appears, browse to and
select the desired folder and save the forecast to it. This change will be
remembered for future saved forecast, including automatically archived ones.
- There is now a check box on the splash screen (of the pretty sunset) allow
you to skip that screen in the future. This was already possible in auto mode
using the 'Start scheduler on next boot-up' option, but it can now be done
without automatically starting the scheduler.
- A bug, which sometimes caused errors (mainly #52: 'Bad File Name or Number')
in auto run (for those not booting WXSIM with a third program such as System
Scheduler) has been fixed. Now, running WXSIM continuously through auto runs
should be much more reliable than before.
Version 12.5.1 (March 23, 2009) had the following changes relative to Version
12.5 (described below):
- A bug, which allowed the time step (determined by output interval and iterations
per interval) to influence the effect of the new temperature (slope) bias
correction factor, has been fixed.
- Values of the new bias correction factors, if used, are now included in
the log.txt or latestlog.txt files (right after urban heat island effect).
- A bug, which occasionally allowed data on a second line of a synoptic report
to be mistaken for a station code, has been fixed.
Version 12.5 (March 21, 2009) had the following changes relative to Version
12.4.5 (described below):
- WXSIM can now read bias correction factors, determined from comparisons
of archived forecasts with actual results (if you have a home weather station
working with WXSIMATE). These are activated by checking the 'Use learned bias
corrections' box on the form which appears when you click 'READY/GFS bias
factors' on the Import form. Note: This feature is restricted to the professional
mode, which all customers who ordered before July 23, 2008 already have. Upgrading
from standard to professional mode costs $50 as of this writing.
- The retrieval module now has the ability to create the correction factors
(for temperature and dew point) referred to above. The relevant new command
buttons are 'Set as Earliest Date', 'Auto Select', and 'Omit'.
- New blue text help items have been added in wxsim.exe and wret.exe to explain
the new learned bias correction features.
- A change was made to wret.exe's Weather Display log file parsing mode, to
handle uncommon log files which omit decimal points in zero rainfall values.
Previously, this could trigger an error at line 578. Also, reading of values
with commas as decimal separators was more widely enabled, hopefully avoiding
some occasional errors.
- Minor cosmetic changes were made.
- WXSIMATE no longer downloads NGM FOUS or NGM MOS, as these no longer exist
as of March 3, 2009. You can still import them into WXSIM from old data files
in case you ever want to dorun retrospective historical runs.
Version 12.4.5 (January 17, 2009) had the following changes relative to Version
12.4.4 (described below):
- A bug in the TTAA (RAOB) parsing system, which could occasionally result
in bad sounding data, has been fixed. This error involved reading a wind field
with a direction of 300 or 305 as a height field for the 300 mb level.
- TTAA parsing was improved to read wind speeds of over 100 knots.
- The range of the temperature controls below the sounding on the upper air
form has been increased from +/-20 Celsius degrees to +/-35. The previous
range had allowed occasional invalid property value errors (#380) in extreme
weather, when 1-Click was pressed, or in auto run.
- An attempt was made to eliminate errors, mainly overflow (#6), occasionally
seen when wret.exe is called in auto run or by clicking the Repeat button.
Specifically, some DoEvents commands were added to the code, to hopefully
get Windows to handle events completely, in the order the code attempts to
execute them. Feedback on whether this attempt was successful would be helpful,
as I cannot seem to replicate the errors.
Version 12.4.4 (January 16, 2009) had the following changes relative to Version
12.4.3 (described below):
- A typo in wret.exe's sounding plots was corrected ('850-500 mb thickness'
was changed to '1000-850 mb thickness').
- Even more safeguards were instituted to prevent loss of import file name.
Note that if the name is somehow temporarily lost, the replacement name will
be c:\wxsim\wdata.txt, so that is a good name to use anyway.
- A new check box, labeled 'ext boot', was added to the Output form as an
option under 'Graphic'. If checked, wret.exe will NOT be run (as it normally
would be to make graphics in auto run or right after clicking "Repeat');
instead wret.exe will simply be prepared to make the graphics and close the
next time it is booted, either manually or by an external program such as
System Scheduler. The reason for this option is an elusive (perhaps dependent
on some unknown condition in Windows) error (#6, Overflow) that some users
have encountered at times. This new check box provides an alternative way
to automatically generate the same plots and soundings. The help files were
also updated accordingly.
- The diagnostic file replog.txt, which was used to narrow down possible causes
of the Overflow error described above, was omitted.
Version 12.4.3 (January 14, 2009) had the following changes relative to Version
12.4.2 (described below):
- More protections were instituted against loss of import file name.
- A bug capable of causing an 'index out of bounds of array' error, especially
in subfreezing weather at sites near sea level, was fixed.
- The retrieval module's sounding bitmap naming convention was changed to
simple serial numbers, instead of skipping. You can still specify a skip interval
to determine which soundings are produced, but the numbering is now simpler.
Version 12.4.2 (January 13, 2009) had the following changes relative to Version
12.4.1 (described below):
- Further work was done to prevent erroneous reports of missing initial surface
- Additional protections were instituted against loss of import file name
Version 12.4.1 (January 12, 2009) had the following changes relative to Version
12.4 (described below):
- A bug (accidentally introduced in 12.4) which caused occasional repeated
lines of text on the output page has been fixed.
- Another bug, which caused an erroneous report of missing initial surface
data, has been fixed.
- A change was made to further ensure preservation of import file names in
the event of errors, including the file not being found.
- A new log file, called replog.txt, was introduced into the code associated
with the Output form's Repeat button, to help track down the cause of a reported
overflow error (#6) which I have not been able to replicate. Any users who
encounter this error should send this file to email@example.com.
Version 12.4 (January 8, 2009) had the following changes relative to Version
12.3 (described below):
- Snow level was added as an output, in menu option #8, in the plain text
output and as an output to .wxf files. This item is calculated by working
downwards through the atmosphere until the first freezing level is found,
and integrating temperature above freezing with respct to height until an
amount of melting energy, based on the precipitation rate, in encountered.
The heavier precipitation, the further below the freezing level it melts.
Snow level is defined here as the level at which a large majority (perhaps
90 percent) of the precipitation is snow, though this is a difficult and somewhat
uncertain variable to calculate anyway. However, it should still be quite
useful for users in mountainous areas. Display parameters can be set on the
new, expanded version of the fog sensitivity form, under.
- The precipitation type algorithm was tweaked in light of further research
and to better coordinate with the new snow level output.
- Slight changes were made to the melting effect of frozen precipitation.
This cooling was reduced by about 10% for sno or snow/rain mixtures. Also,
an error which reversed the melting effects of 'snow/rain' and 'rain/snow'
- The latest.csv file (and any archived or saved versions of it) has been
augmented to include freezing level and snow level. These are listed on the
far right side.
- The retrieval module, wret.exe, was expanded to accommodate snow level,
which is now displayed in the 'thickness' category. The graphical displays
in this category are now more precisely labeled on the plots.
- The sounding plots in the retrieval module were changed to include snow
level, and also to display height, temperature, and pressure on the graph
at the tip of the mouse cursor, to enable more precise examination of the
- The retrieval module now allows production of bitmaps of soundings, by checking
both the 'Save Bitmap' and 'Inc Soundings' boxes on the Plots form.
- The retrieval module's bitmaps are now cropped to reduce the size. They
can be converted to other formats, such as PNG, by using a third-party program
such as IrfanView (www.irfanview.net).
- Changes were made to reduce the likelihood of an error (other than File
not Found or Bad File Name or Number) causing a deletion of the name of the
file to import.
GFS data consisting of zeros (as may happen if that system fails to actually
parse the data) is now treated as being simply absent. This may reduce the
possibility of any errors resulting from such an event.
- Additional notations have been added to the plain text output to indicate
when WXSIM fails to find various data types - such as GFS, READY, or METAR,
SYNOP, or local station data - to serve as a warning of possible inaccuracy
in the forecast.
- An error log (wretlog.txt) was created for the retrieval module (wret.exe)
to help diagnose any future errors occurring in that program.
Version 12.3 (November 30, 2008) had the following changes relative to Version
12.2 (described below):
- The boot up default values for wind speed, haze, and level 2 and 4 cloud
cover now represent rough climatological normals for the site. Also, if no
temperature data is manually entered or imported (via METAR, SYNOP, or from
local station data), temperature and dew point will default to climatological
normals for that time of day under the given wind and cloud conditions. This
makes more reasonable auto forecasts in the rare cases in which data is missing.
It also allows for easy production of climatological normal temperature curves
in a research or educational mode.
- Handling of date formats is now more versatile, allowing use of yyyy-mm-dd
format (used in Sweden, Poland, and perhaps some other places). There are
still only two format choices (month/day/year and day/month/year) under Preferences,
but WXSIM will now at least correctly populate the entry form on boot-up regardless
of Windows regional settings.
- A bug which caused errors and loss of import form settings, after failure
to find GFS or READY data in auto mode, has been fixed. In auto mode, no warning
will appear to alert the user to the lack of data, but a message will be included
in the latestlog.txt file (and the forecast may be rather monotonous).
Version 12.2 (November 12, 2008) had the following changes relative to Version
12.1 (described below):
- A new feature was added (on the Interrupt Planner) for specifying the number
of hours permitted to pass between advection prompts. This is intended to
facilitate updates to advection data (mainly using MOS, which is available
only for North American sites) in cases where wind shifts remain below the
specified tolerance. A good default figure is about 30 hours.
- An option was added (on the Output Form) to specify saving of only the .wxf
files when archiving forecasts. This is intended to minimize disk space usage
for users archiving large numbers of forecasts. Manually saved forecasts will
continue to be saved as all five file types even when automatically archived
- Improved error handling and messages have been provided for the case of
clicking 'Get Data' on the Import form with a blank or non-existent file name
in the box.
Version 12.1 (October 4, 2008) had the following changes relative to Version
12.0 (described below):
- A problem, which could produce 'Invalid property value' errors after importing
home weather station data showing very heavy rain, has been corrected.
- A new safeguard was added, against bad METAR wind speeds imported during
autorun (for the home site). It defaults them to 7 (mi/hr, km/hr, or whatever
your units are), though this can then be overwritten with your own local station
Version 12.0 (July 23, 2008) had the following changes relative to Version
11.8.7 (described below):
- Slightly increased thresholds for mentioning fog in the plain text output.
- Expanded use of 'slight chance of' precipitation to include the lower part
of the range previously covered by 'chance of'.
- Added an option (under Preferences, along with the existing minimum UV index
threshold) for omitting mention of very light or low probability precipitation
from the plaintext output.
- Added site, date, and time information to the Comments section of saved
- Slightly reduced severity of convective bulletin outputs for Northwest European
mode (in both wxsim.exe and wret.exe)..
- Added information on some forms, including clarification of the use of certain
- Made numerous changes to facilitate the use of different registration codes
for different levels of use: standard and professional.
- Changed the demo cty.fdt file to include just two sites: Atlanta - which
illustrates professional mode - and Marks Point, Australia, which shows standard
- Updated price structuring to cover four combinations of mode and of level
of customization (basic and enhanced).
- Updated surface and upper air databases used in customizing WXSIM.
- Changed the TM for the intended WXSIM trademark to ® indicated the recent
registration of WXSIM with the United States Trademark and Patent Office.
Version 11.8.7 (June 27, 2008) had the following changes relative to Version
11.8.6 (described below):
- Added the ability to read Dobson unit values for up to 10 days, to be used
in UV index calculations. These values can be obtained from web sites (see
blue text help for Ozone on Data Entry form) and used to create a simple data
file. A sample of such a file, dobunitsAtl.txt, is now included in WXSIM's
distribution and upgrade packages.
- The UV index algorithm now includes reflected radiation off of snow cover,
plus some consideration of surface type (forest, grass, desert, etc.).
- Changed the interpolation scheme for determining level 1 temperatures from
GFS or READY data, in order to avoid some bad results that could previously
occur when surface pressures are very low.
- Made forecast log show correct version number.
- Allowed for comma as the decimal separator in the Distance Ratio item on
the Advection form.
Version 11.8.6 (February 23, 2008) had the following changes relative to Version
11.8.5 (described below):
- MOS advection in auto run after wind shifts now defaults to using smooth
curve fit, with 'enforce monotone' if you so chose on the Auto Run form. Previously,
it defaulted to a best fit line, which appears to have subdued temperature
advection after sharp frontal passages too much.
- The retrieval module (wret.exe, accessible from the main program via File/Retrieve)
now enables comparison of previous forecast with Ambient's Virtual Weather
Station software, in addition to Weather Display and WeatherLink.
- The help files were updated to reflect the above changes.
Version 11.8.5 (January 21, 2008) had the following changes relative to Version
11.8.4 (described below):
- The suffix 'NDV' (No Directional Variation) is now understood by the METAR
parsing routine, as applied to visibility reports.
- The 'maximum distance' value (which you can control with a scroll bar on
the Advection form) now applies to the cutoff time for advection (when you
can choose to continue with a decay). Previously the maximum distance simply
determined which points to leave out of the curve fit. This change should
help limit temperature excursions in cases of sparse, inappropriately fit
data, especially in auto run, when you are not there to oversee the profile.
- The auto run form has a new check box option for enforcing the monotone
condition on smooth curve fits in initial regional data advection in auto
run mode. Otherwise, WXSIM decides between monotone and not monotone fits
based on the amount of temperature inversion, with monotone applied only if
a significant inversion exists. As in (2) above, this change is intended to
reduce strongly curved advection profiles, which can result from sparse data
(such as near coasts).
- The help files were updated to reflect (2) and (3) above, and generally
explain auto run advection options better.
Version 11.8.4 (January 14, 2008) had the following changes relative to Version
11.8.3 (described below):
- Checks were added to prevent use of regional data advection in auto run
mode when no sites (METAR, SYNOP, or MOS) are found more than one fifth the
maximum advection site distance (which you can set on the Advection form).
This should prevent some unrealistic temperature excursions that were occurring
in auto run, mainly for some near-coastal sites.
- Regional data advection is now weakened in cases of poor flow curvature
fits. Specifically, flow fits of 90 percent or better remain as they were.
Flow fits below 90 percent are weakened in such a way that, for example, a
45 percent fit now has 71 percent as much effect as previously.
- The message box saying that MOS data has run out now appears even if the
user makes repeated attempts to use this data; previously it had appeared
only the first time). In such cases, the Import form is now closed to allow
immediate access to the Advection for, to allow a new choice.
- The "sleet/mix" precipitation type no longer contributes to above
ground freezing rain accumulation.
- The summary.txt file is now saved in the directory in which WXSIM was first
booted up (usually c:\wxsim), which could in some cases be different from
the current directory at the time the file is saved.
- The version number in the log file was updated to 11.8.4 (it had been left
as 11.8.2 in Version 11.8.3).
Version 11.8.3 (December 27, 2007) had the following changes relative to Version
11.8.2 (described below):
- The auto haze routine was improved based on a recent analysis of up to 25
years of visibility data for a few U.S. cities. Generally, the haze amount
is somewhat less sensitive to wind speed and recent precipitation than before.
Also, a new algorithm allows the initial (input or imported) visibility and
associated haze value to decay towards the auto haze amount, rather than abruptly
changing to it.
- A new output file, called summary.txt, is now produced with each forecast
and placed in the directory with WXSIM. This file is a copy of the "Summary"
, "Supplemental data", "Nightime lows and daytime highs",
and "Totals" which appear in the original forecast.
- The criteria for the plaintext output's phrases "temperatures rising
after midnight" and "temperatures falling in the afternoon"
have been changed slightly, so that average temperatures must rise or fall
by at least 0.3 Celsius degrees (0.54 Fahrenheit degrees) to trigger inclusion
of these phrases. This will prevent the phrases from appearing when temperatures
are almost steady.
Version 11.8.2 (December 1, 2007) had the following changes relative to Version
11.8.1 (described below):
- A bug, preventing second and subsequent scheduled auto runs with WXSIM remaining
open, had appeared first in version 11.8. This resulted from a mismatch between
a timer in the program and the way it was being read. It has been fixed.
- A bug which prevented MOS data from being read on the first try after a
"MOS not started yet" message, has been fixed.
- Additional diagnostic items were added to the log file.
Version 11.8.1 (November 25, 2007) had the following changes relative to Version
11.8 (described below):
- A bug introduced by a changed yesterday was fixed. In particular, users
with day/month/year format would see an error message about the month being
greater than 12 pop up incorrectly. The protection feature still exists, but
the problem at boot up has been eliminated.
- Additional small changes were made to prepare for the multi-site controller
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
- 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
- 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
- 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
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
- The help file wxsimhelp.doc was updated to include information on the READY/GFS
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
- The METAR signifier "NCD" is now recognized, as meaning "no
- 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
- 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
- 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
- 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
- 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
datas 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
- 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):
Version 11.0.2 (August 5, 2006) and has the following changes relative to Version
11.0.1 (described below):
- The retrieval module's comparison feature was expanded to include input
from Davis WeatherLink files, via a new feature in WXSIMATE which saved files
in text format as they are read for local station import.
- The ability was added to list the files being compared and/or combined in
the retrieval module.
- Compared and/or combined data in the retrieval module in the retrieval module
can now be saved as a spreadsheet-viewable .csv file.
- The 'Combine' check box now maintains its state (checked or unchecked) between
comparison retrievals in the retrieval module.
- The second weather text item now appears in WXSIM's saved forecast .csv
files (it was intended to appear in earlier versions, but failed to).
- The column headings in WXSIM's saved .csv files are now left-justified (instead
of right-justified), to make them more visible.
- Enabled printing of plain text forecast with 'Graph and Summaries' option
(in addition to the other options).
- A bug, which could cause repeated dates when retrieving forecasts made using
daylight savings time, was fixed.
Version 11.0.1 ( August 2, 2006) had the following changes relative to Version
11.0 (described below):
- 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
- 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
- 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
- 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
- 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
- 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
- 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
- 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
- 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
- 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
- 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
- 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
' 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
- 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
- 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
- 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):
Version 9.5 (December 29, 2004) had the following changes relative to Version
9.4 (described below):
- The extended advection map data, including information for coloring water
blue, was inadvertantly omitted from at least some of the recently released
packages (probably startng with Version 9.3). They are included now.
- NOAA just changed the ETA model's name to NAM. WXSIM can now handle this,
and is still able to import old ETA data as well. All references to 'ETA'
in the help files were also changed to 'NAM'.
- Small changes in the documentation were made, including the option of paying
for WXSIM or WXSIMATE via PayPal.
Version 9.4 (December 14, 2004) had the following changes relative to Version
9.3 (described below):
- Minimum and maximum relative humidity for each day was added to the 'Summary'
output. Similarly, average relative humidity for all complete days was added
to the 'Totals'.
- Spacing between numbers was improved in the 'AM Lows and PM Highs' output,
so that the values would more dependably line up underneath the day headings,
even in the case of single digit values (common when using Celsius in winter).
The same correction was applied to the Retrieval module.
- Minor cosmetic changes were made to both the main module and the retrieval
- Minor changes were made in the help files for both the main module and the
- A change was made to accomodate 'FW' (few clouds) as a sky cover type in
the MOS parsing routine. (When encountered previously, this had triggered
a message which said 'Bad sky cover data. Assuming clear.')
Version 9.3 (December 10, 2004) had the following changes relative to Version
9.2 (described below):
- The text box for the name of the data file to be imported has now been enabled,
meaning you can now type directly into it as an alternative to selecting it
from the drive, directory, and file list boxes below. This may be faster if
you save a lot of old data files which you might have to scroll through. Also,
an error trap for bad file names has been added.
- A small bug affecting the displayed solar and UV radiation on the Data Entry
form has been fixed. This bug had allowed imported READY data to alter to
sun angle used in these displays, though the resulting errors never appeared
in forecast output.
- Several, mainly cosmetic changes were made, including the wording and positions
of the Introduction, Registration and License forms.
- A setup/installation program called setupwxm.exe was created (using Inno
Setup), to serve as the primary mode of distribution for this new version.
A similar setup program, setupwmt.exe, was created for distribution of WXSIMATE
Version 1.4 (compiled on December 10, 2004).
Version 9.2 (October 18, 2004) had the following changes relative to Version 9.1
- 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
- Changes were made to ensure compatibility of local data import with the
latest version (1.3) of WXSIMATE.
- Slight cosmetic changes were made, including a new icon, wider text and
list boxes on the Data Import form, and a more thorough explanatory note on
the Save Data form.
- An error trap was added to prevent runs with zero barometric pressure (i.e.
resulting from incomplete METAR data being imported).
Version 9.1 (July 31, 2004) had the following changes relative to Version 9.0
- 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
- A more versatile format for the files localcal.txt and localdat.txt (produced
by WXSIMATE) was adopted and allowed for in WXSIM, so as to avoid errors that
occured in German language Windows settings. This error had resulted from
conflicts between periods and commas as decimal points, and is now avoided
by storing values as large integers.
- Slight cosmetic changes were made to some forms.
Version 9.0 (July 7, 2004) had the following changes relative to Version 8.9.1
- Improvements were made to the advection map backgrounds. The data now covers
the entire world, and some additional details and resolution have been added
- mainly large lakes and bays, mainly in North America. Also, bodies of water
are now displayed blue (before, all backgrounds were white).
- The program now saves the name of the last imported data file, and displays
it as the default the next time you use the program. This can save time in
selecting the file for import, especially if you use the same name each time
(though if you intend to archive the data, this may not be the best choice).
Version 8.9.1 (January 24, 2004) had the following changes relative to Version
8.9 (described below):
- WXSIM can now use data from a new companion program, WXSIMATE, which can
greatly speed and ease collection of data from internet sources, and also
allows import of many data types from home weather stations (at this point
only those using Davis WeatherLink 5.0 and later). WXSIM can also open WXSIMATE
if the latter is present in the same directory.
- The calibration run is now able to use WXSIMATE data to simulate conditions
leading up to the present. This may increase forecast accuracy somewhat, especially
on days when large changes in cloud cover, wind speed, or precipitation have
occured since the last 'midpoint' of the diurnal temperature curve.
- A new 'Refinement' item has been added: "Stop AM Rain". This addresses a
problem that has existed ever since WXSIM began using external model data
several years ago. In particular, much of the warm season rain in many areas
consists of heat-induced afternoon and evening thundershowers. The 3 or 6
hour resolution model data (NGM, ETA, or GFS) as used by WXSIM, however, often
started rain in the late morning or early afternoon, prematurely cutting off
heating and underforecasting the high temperature. This new option lets you
specify the earliest and latest times for rain to occur. Carefully devised
location and season-dependent default times are provided, but can be overridden.
- A couple of related bugs involving the Interrupt Planner, particularly when
using READY data or clicking changes, have been resolved. These sometimes
caused parts of the data to dissapear on subsequent runs.
- Recall of the Monotone and Best Fit check box values, after clicking 'Use
Previous' on the advection form, may not have worked properly in some earlier
versions. This has been fixed.
- The activation indicator for 'Sea Breeze' at the bottom of the Output form
now properly indicates 'Mtn/Vly Breeze' if the mountain/valley breeze routine
is in use instead of the sea breeze one.
- A very minor bug was discovered, in which second and later imports of FOUS
data would automatically be active without the user authorizing it by clicking
the 'Use FOUS' button. Now, any additional FOUS imports must be freshly authorized.
Also, the 'Clear' button below the Use FOUS button now says 'Clear FOUS'.
- Several minor cosmetic changes were made to a number of forms, including
enlargement of the raw surface data view box accessed from the Import form.
Also, the 'Scanning for METAR' message now properly says 'Scanning for MOS'
that is the case.
- This is not a change in the program itself, but note that FSU now provides
the buoy data formerly available at PSU. The new web address is 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
- A minor, rarely encountered bug - in which the program failed to remember
the latest choice of synoptic versus METAR as the default surface data type
- was corrected.
Version 8.9 (November 8, 2003 had the following changes relative to Version 8.9(described
- 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
- 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
- A new 'Superimpose' button on the plotted data form in wxrw1.exe now allows
plotting of multiple forecasts on the same graph, for comparison. There is
also a new check box allowing the user to specify whether or not subsequent
plots are to use thicker lines, to distinguish them from earlier ones.
- A minor bug that sometimes caused omissions of convective bulletins in wxrw1.exe's
text output was fixed.
- The starting time of a saved forecast was added to the identifying information
when selecting a file to view in wxrw1.exe. Also, the text color of this identifying
information was changed from gray to black to improve readability.
Version 8.8.2 (September 5, 2003) had the following changes relative to Version
8.8.1 (described below):
- Most of the commonly viewed forms in both the main program (wxsimw.exe)
and the retrieval module (wxrw1.exe) were enlarged significantly, from about
640x480 to 800x600 pixels, allowing much larger graphics and in many cases
more space between controls.
- The optical effects of clouds were altered slightly, based mainly on careful
studies I did using NOAA's SAMSON data and nearly two solid months of METAR
data for KATL correlated with measurements of solar radiation archived every
10 minutes using a Davis Vantage Pro weather station I recently installed
at Woodward Academy, where I teach. I also did some analysis of hundreds of
forecast I've logged over the years using WXSIM, to see if days with small-medium
diurnal ranges (and therefore likely partly to mostly cloudy) had these diurnal
ranges suppressed in the forecast; they did, though the effect was slight,
but corroborated the need for at least a small change. The main effect of
these changes is a modest reduction in the default opacity of clouds (including
the auto cumulus and stratus routines as well as clicked and interrupt input
and imported METAR or synoptic data), given areal coverage, especially under
partly to mostly cloudy skies. Some of the reason for this is consideration
of sunlight reflected off the sides of clouds (the cloud gap effect), which
had not been previously taken into account. The main effect here is a small
(about 1 degree C or nearly 2 degrees F) increase in diurnal range on partly
to mostly cloudy days. Another small change is that cirrus clouds now have
enhanced reflectivity with lower sun altitudes.
- While doing the studies above, I found that clear days had very slightly
too much diurnal range, by perhaps 2% (about half a degree F) on average.
Slight changes were made to correct this.
- In conjunction with the studies mentioned above, in (2), solar radiation
(visible, in Watts per square meter) was made an output, also saved in .wxf
files for use in the retrieval module. The solar radiation is based largely
on the Davis data from my school, but also from the SAMSON data, especially
a period of actual (not modeled) measurements from the Georgia Institute of
Technology, mainly in 1981. This output takes into account sun angle, distance
from sun, haze, clouds, and elevation.
- Ultraviolet Index is now also output, along with solar radiation, in a new
output menu suite (#9). UV index is based largely on data from the Vantage
Pro station at my school, but also from other sources, such as
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
- 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
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
- 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
Version 8.8 (July 15, 2003) had the following changes relative to Version
8.7.2 (described below):
Version 8.7.2 (June 14, 2003) had the following changes relative to Version 8.7.1
- 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
- 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
- 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
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
- 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
- Changes and additions to the help file were made in light of the above
- 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):
Version 8.5 (December 27, 2002) had the following changes relative to Version
8.4.2 (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
- A change was made in the reading of '6 hour' precipitation totals in 3-hour
output READY data (such as AVN short range). I had assumed previously that
the values listed in the file were actually 6 hour totals, but I've been informed
by Glenn Rolph (the site's webmaster) that the figures are derived by subtraction
of successive 3-hourly data, so that, in effect, they are 3 hourly totals.
This means that, until now, WXSIM's precipitation totals - when derived from
3-hourly AVN data - were only about half of what they should have been (perhaps
more like 3/4 if FOUS products were used in the run as well). Now WXSIM should
mirror the AVN totals listed on READY's meteogram graphic (unless FOUS data
is mixed in). The AVN datasets are being renamed GFS, but they should be read
by WXSIM in the same way as the AVN.
Version 8.4.2 (May 31, 2002) had the following changes relative to Version 8.4.1
- 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
- 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.
Version 8.4.1 (May 4, 2002) had the following changes relative to Version 8.2.9
- A bug that prevented complete culling of synoptic and METAR files in some
cases (for recent, large customizations) was corrected.
- A change was made to enable import of a certain (European, primarily?)
RAOB format that had been rendered unreadable by a recent change on FSU's
interactive text web page.
- A small change to the retrieval program (wxrw1.exe) now saves the user's
choice of North American or Northwest European stability indices upon exit.
Version 8.2.9 was completed on March 3, 2002 and had the following changes relative
to Version 8.2.6 (described below):
- WXSIM can now read NGM and ETA FOUS data from FSU's newly (May 3) reorganized
web page, which presents the data with leading spaces not present before.
WXSIM can still read any format that it could before. The new FSU page is
- 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
- 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
- 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
- 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)
- 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
Version 8.2.6 was completed on February 24, 2002 and had the following changes
relative to Version 8.2.5:
- A change was made to improve operation of the 'Reduce superadiabatic' option
when FOUS data is also in use.
- A bug in the regional advection routine was corrected. This started with
a misnamed variable in Version 8.2.4 and caused fairly small, but sometimes
significant errors in the adjustment of data for advection sites. It tended,
in general, to reduce the effectiveness of both cold and warm air advection.
- Fairly small adjustments, motivated by testing on both recent and historical
data, were made involving the handling of unseasonably cold air. In particular,
the diurnal temperature range in cold air masses was increased slightly, and
the rate of air mass modification (in this case, warming) was made more dependent
on the depth of the cold air mass; deeper cold air now modifies more slowly
relative to shallow cold air than before (though shallow cold air may now
modify more quickly than in earlier versions).
Version 8.2.5 was (February 18, 2002) had the following changes relative to Version
- 900 or 950 mb relative humidities can now be imported from READY as a substitute
for 925 mb, which is not available in some models (i.e. ETA 91 km).
- A message box now appears after READY import if multiple models were found
and mixed. It also tells which items were averaged.
- A bug, which sometimes made the import form look for home site data when
it should be seeking advection data, was corrected. This bug had occured if
multiple attempts to access the import form were made from the advection form.
- A shower toggle interrupt item was added. Pressing 'p' (or accessing Interrupts/Precipitation/Toggle
Showers) during the forecast run toggles the FOUS and/or Interrupt Planner
shower option on and off.
- The following changes were made to the Retrieval program: Up to 10 days
of data can be retrieved, and the last choice of skew versus rectangular detailed
sounding plots is saved on exit.
Version 8.2.4, finalized January 20, 2002, has the following changes relative
to Version 8.1 (described below):
- 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'
- 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
- 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):
Version 7.3, finalized April 12, 2001, includes one change from Version 7.2.9,
in response to a small change in the format of READY meteogram data: the year
is now four digits instead of two. Version 7.3 properly reads the new format as
well as the older ones.
- 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
- 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
- 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:
Version 7.2.8 (finalized March 17, 2001) corrected a problem which allowed the
duration of READY data to interfere with that of FOUS data. Version 7.2.7 (March
17, 2001) allowed for import of new, slightly differently formatted (in the date/time
section - already corrected in version 7.2.6 - and now also in the forecast hour
line) READY meteogram data, though it can still import the older formats, too.
Version 7.2.5 (January 25, 2001) added the option of dots as date separators,
as used in some parts of Europe. Also, an oversight, which had allowed the chosen
time interval to influence the effect of the (optional) Recent Temperatures/Last
4 Days input, was corrected. Version 7.2.3 (January 11, 2001) corrected a rarely
encountered division by zero error that happened when importing READY meteogram
data if the V component of wind was exactly 0.00. Version 7.2.2 (January 9, 2001)
improved handling of the effect of nearby moderate-sized bodies of water for certain
sites. Version 7.2.1 (December 31, 2000) corrected a minor RAOB import bug in
Version 7.2 that had caused erroneous 1000 mb heights when that height was below
- 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
- 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
Version 7.1.3, finalized November 5, 2000, contained the following changes from
- 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
- 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
- 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
- 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
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
Version 7.0 was finalized on August 18, 2000, and included the following improvements
over Version 6.4:
Version 6.4 was finalized on February 19, 2000, and included the following improvements
over Version 6.0:
- 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
- Revisions and improvements to the retrieval program (WXRW1.EXE), including
minor bug corrections, the addition of a comments section, and saving of settings
- 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
- The standard of using commas for decimal points (in certain European countries)
is now supported, if Windows is set accordingly.
Version 6.0 included several advancements made since the release of V5.4 about
a year ago, as follows:
- 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
- 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
- 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
- There is now an option for smooth, least-squares regression fits for advection
data, regardless of the number of sites chosen.
- There is now an option to select and use all imported METAR and buoy data
with a single mouse-click.
- Certain types of ocean buoy data (namely, the format used on Penn State's
web page) can now be imported and used.
- A new 'status' bar at the bottom of the data output form keeps the user
informed as to whether or not various features (i.e. advection, FOUS, sea
breeze, auto cumulus, etc.) are currently active.
Between Version 4.0 and 5.4, a MAJOR data collection and program calibration effort
was undertaken. This involved many years' (up to 30 in one case) worth of hourly
surface data from several stations, correlated with upper air data using a program
written especially for this purpose. (The data sources were the National Climatic
Data Center's SAMSON CDROM and North American Upper Air Data 1946-1996 CDROM.
I wrote the extraction and analysis program).
V5.4 included many improvements made since the release of V4.0 about two years
ago, as follows:
- A new low-level-thickness-based maximum temperature routine
- Additions to the help files and the user's guide
- Improved handling of slowing of cold air advection by mountains
- Maximum daily temperatures at high latitudes in winter, especially with
snow cover, were found to be occuring too early in the afternoon. This has
been corrected to fit recent data analysis.
- Increased versatility has been added to the customization process to better
fit the diurnal temperature curve for arid sites and to better model diurnal
wind variations at specific sites.
- The data import feature has been modified slightly to eliminate confusion
between METAR and other types of data having station ID in the same field.
- More thorough screening is now available for 'weeding out' in-between-hours
METAR reports if desired.
- A bug that sometimes inappropriately deactivated the low stratus routine
was corrected, and associated default upper level dew point routines were
- Improved upper air temperature routines
- Improved initialization of boundary layer temperatures
- Ability to re-generate advection data and upper air adjustments from previous
- 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