Public Sub WEATHER()

'This is intended to help authors of third-party scripts for displaying WXSIM data, 
'or for general interest for WXSIM users.  A few lines irrelevant to this purpose have
'been removed.  The variable wr$ is the weather type 1 and wr2$ is weather type 2,
'which is of secondary interest.  The below is NOT the decision tree for output appearing
'in plaintext.txt.  That is a separate algorithm developed much later in response to
'requests for plain language output from WXSIM for standard time periods such as 6 or
'12 hours.  There are occasionals in which a weather type, such as fog, may appear in
'one of these outputs (scrolling text/latest.csv or plaintext.txt) and not in the other.
'
'c(i) is fractional cloud cover at the ith layer
't(i) is cloud opacity on a 0-5 scale at the ith layer
'ke(i) is temperature at the ith layer
'fg is a fog variable equal to 1 for no fog and approaching 0 for very dense fog
'te is near-surface air temperature in Kelvins
'dn is near-surface dew point in Kelvins
'te is near-surface wet bulb temperature in Kelvins
'rh is near-surface relative humidity in %
'ws is 10 meter wind speed in miles per hour
'
'There are more variables I will not define here
    
skd = 1
For i = 1 To 5
 skd = skd * (1 - c(i) * t(i) / 6)
Next
skd45 = 1
For i = 4 To 5
 skd45 = skd45 * (1 - c(i) * t(i) / 6)
Next

wr$ = "CLEAR"
If skd < 0.97 Then wr$ = "CLR-FAIR"
If skd < 0.94 Then wr$ = "FAIR"
If skd < 0.9 Then wr$ = "FAIR-P.C."
If skd < 0.83 Then wr$ = "P.CLOUDY"
If skd < 0.7 Then wr$ = "P.-M.CLDY"
If skd < 0.6 Then wr$ = "M.CLOUDY"
If skd < 0.5 Then wr$ = "M.C.-CLDY"
If skd < 0.4 Then wr$ = "CLOUDY"
If skd < 0.27 Then wr$ = "DNS.OVCST"
If wr$ = "CLR-FAIR" And al > 0.04 Then wr$ = "SUNNY"
If wr$ = "FAIR" And al > 0.04 Then wr$ = "M.SUNNY"
If (wr$ = "SUNNY" Or wr$ = "M.SUNNY") And hz >= 2 Then wr$ = "HAZY SUN"

wr2$ = ""
fg = 1

dewf = a / a2 * (dn - te + 2.7 + rtc / 4) * 4 / (ws + 6) + 2 * tvp
dewfvly = a / a2 * (dn - (tvy + 0.9) + 2.7 + rtc / 4) * 4 / (ws + 6) + 2 * tvp
If dewf > 0.3 Then wr2$ = "LIGHT DEW"
If dewf > 0.6 Then wr2$ = "MOD. DEW"
If dewf > 0.9 Then wr2$ = "HEAVY DEW"
If dewfvly > 0.3 And tvy - iv2 < 271.3 Then wr2$ = "SCTD.FROST"
If dewf > 0.3 And grasst < 272.1 Then wr2$ = "LT. FROST"
If dewf > 0.6 And grasst < 271.3 Then wr2$ = "MOD. FROST"
If dewf > 0.9 And grasst < 270.5 Then wr2$ = "HVY. FROST"

If fa$ = "n" Or rh < rhs Then fg = 1: e(0) = 1: ga(0) = 0

If fa$ = "y" And rh >= rhs Then
 fg = (1 - rtc / 8) * 0.7 * (rh - rhs) / 9 * (4 - Sqr(Abs(5 - ws))) * (32 - bp) * 0.17 * (18 + q3) / 20
 fg = 1 - fg * (dn / 287) ^ 8 - (tvp - tvp91) / 4 * fsen / 3
 If fg < 0 Then fg = 0
 If fg < 0.3 Then fg = 0.3 - 0.1 * ((0.3 - fg) / 0.3) ^ 1
 fg = fg ^ ((fsen + 2) / 6)
 If fg > 1 Then fg = 1
 fg = 0.5 * (1 - (1 - fg) * w(1) * w(2) * w(3) * w(4) * w(5)) + 0.5 * fg
End If

e(0) = fg ^ 0.3 / (1 + 1.6 * (1 - c(2)) * ip ^ 0.3): ga(0) = (te / 100) ^ 4 * (1 - e(0))
If fg < 0.85 Then wr2$ = "LIGHT FOG"
If fg < 0.63 Then wr2$ = "MOD. FOG"
If fg < 0.35 Then wr2$ = "DENSE FOG"
If ip = 0 And prd < 0.1 And prs < 0.1 Then GoTo 750
ptp = 1: fpt = 1
If ip >= 3 Then wr2$ = "HEAVY RAIN"
If ip < 3 Then wr2$ = "MOD. RAIN"
If ip < 2 Then wr2$ = "LIGHT RAIN"

If ip < 1 Then wr2$ = "DRIZZLE"
If ip = 0 Then
 If prd > 0.1 Then wr2$ = "CHNC. DRZL"
 If prd > 0.3 Then wr2$ = "PROB. DRZL"
 If prs > 0.1 Then wr2$ = "CHNC. SHWR"
 If prs > 0.3 Then wr2$ = "PROB. SHWR"
End If

styp = 1
If c(3) * t(3) >= 3 And ke(3) < 271 Then styp = 2
If styp = 2 And ke(3) < 267 Then styp = 3
If c(3) * t(3) < 3 And (ke(3) + ke(2)) < 546 Then styp = 2
If styp = 2 And (ke(3) + ke(2)) < 543 Then styp = 3
If ke(2) > 272 + ip / 3 And styp = 3 Then styp = 2
If ke(2) > 274 + ip / 3 Then styp = 1

fpt = 1
rhfc = ke(2) + ke(3) + 0.4 * rh + 1.4 * (1.4 * te + dp)

If c(1) < 0.3 And ke(2) < 277 And te < 280 Then
 If rhfc < 1488 Then fpt = 3: If te < 273 Then fpt = 4
 If rhfc < 1475 Then fpt = 6
End If

eft = (ke(1) + te + wb) / 3
fp = -2.5 * Atn((ke(2) - 273) / 3) + 273
            
If styp = 1 Then
 If te <= 273 Then fpt = 2
 If eft < fp + 1 Then fpt = 3: If te <= 273 Then fpt = 4
 If ke(2) < 273 And eft < fp Then fpt = 5 'not sure about this one
 If eft < fp - 1 Then fpt = 6
 If te > 280 Or wb > 274.9 Or eft > 276.7 Then fpt = 1 'to protect against crazy warm snow
 If te = 0 Then MsgBox "Zero absolute temperature, indicating a possible data problem.  Please report to the program's author.": fpt = 1 'to protect against crazy random freezing rain
End If

If styp = 2 Then
 fpt = 9
 If te > 277.9 Or wb > 274.3 Or eft > 275 Then fpt = 10
 If te > 280 Or wb > 274.9 Or eft > 276.7 Then fpt = 1
 If te <= 273 Then fpt = 4 'may change this to frz rn/mix
 If eft < fp + 1 Then fpt = 5: If te <= 273 Then fpt = 4 'may change wording to rn/mix
 If eft < fp - 1 Then fpt = 7
 If te > 280 Or wb > 274.9 Or eft > 276.7 Then fpt = 1 'to protect against crazy warm snow
End If

If styp = 3 Then
 fpt = 8
 If (te > 276.6 Or wb > 273.8 Or eft > 273.9) Then fpt = 9
 If (fpt = 8 Or fpt = 9) And (te > 277.9 Or wb > 274.3 Or eft > 275) Then fpt = 10
 If (fpt = 8 Or fpt = 9 Or fpt = 10) And (te > 280 Or wb > 274.9 Or eft > 276.7) Then fpt = 1
End If

If (fpt = 1 Or fpt = 8 Or fpt = 9 Or fpt = 10) Then
 If fpt = 1 And snlvl < el + 700 Then snlvl = 0.55 * snlvl + 0.45 * (el + 700)
 If fpt = 10 Then snlvl = 0.55 * snlvl + 0.45 * (el + 400)
 If fpt = 9 Then snlvl = 0.55 * snlvl + 0.45 * (el + 100)
 If fpt = 8 And snlvl > el - 200 Then snlvl = 0.55 * snlvl + 0.45 * (el - 200)
 fptt = fpt: If fpt = 1 Then fptt = 11
 tfsl = 12 + (snlvl - el - 1000) / 300
 If tfsl > 12 Then tfsl = 12
 If tfsl < 7 Then tfsl = 7
 fptt = CInt(0.33 * tfsl + 0.67 * fptt)
 fpt = fptt: If fpt = 11 Then fpt = 1
End If

If fpt = 2 Then
 ptp = 2
 If ip >= 3 Then wr2$ = "ICE STORM"
 If ip < 3 Then wr2$ = "FRZ. RAIN"
 If ip < 1 Then wr2$ = "FRZ. DRZL"
 If ip = 0 Then
  If prd > 0.1 Or prs > 0.1 Then wr2$ = "CH. FRZ.RN"
  If prd > 0.3 Or prs > 0.3 Then wr2$ = "PR. FRZ.RN"
 End If
End If

If fpt = 3 Then
 ptp = 2
 wr2$ = "RAIN/SLEET"
 If ip = 0 Then
  If prd > 0.1 Or prs > 0.1 Then wr2$ = "CH. RN/SLT"
  If prd > 0.3 Or prs > 0.3 Then wr2$ = "PR. RN/SLT"
 End If
End If

If fpt = 4 Then
 ptp = 2
 wr2$ = "SLT/FRZ.RN"
 If ip = 0 Then
  If prd > 0.1 Or prs > 0.1 Then wr2$ = "CH. SLT/FR"
  If prd > 0.3 Or prs > 0.3 Then wr2$ = "PR. SLT/FR"
 End If
End If

If fpt = 5 Then
 ptp = 2
 wr2$ = "SLEET/MIX"
 If ip < 1.7 Then wr2$ = "LT.SLT/MIX"
 If ip > 2.5 Then wr2$ = "HVY.SLT/MX"
 If ip = 0 Then
  If prd > 0.1 Or prs > 0.1 Then wr2$ = "CH.SLT/MIX"
  If prd > 0.3 Or prs > 0.3 Then wr2$ = "PR.SLT/MIX"
 End If
End If

If fpt = 6 Then
 ptp = 3
 If ip <= 1.9 Then wr2$ = "LT. SLEET"
 If ip > 1.9 Then wr2$ = "MOD. SLEET"
 If ip > 2.8 Then wr2$ = "HVY. SLEET"
 If ip = 0 Then
  If prd > 0.1 Or prs > 0.1 Then wr2$ = "CHNC.SLEET"
  If prd > 0.3 Or prs > 0.3 Then wr2$ = "PROB.SLEET"
 End If
End If

If fpt = 7 Then
 ptp = 3
 wr2$ = "SLEET/SNOW"
 If ip < 1.6 Then wr2$ = "LT.SLT/SNW"
 If ip > 2.4 Then wr2$ = "HVY.SLT/SN"
 If ip = 0 Then
  If prd > 0.1 Or prs > 0.1 Then wr2$ = "CH.SLT/SNW"
  If prd > 0.3 Or prs > 0.3 Then wr2$ = "PR.SLT/SNW"
 End If
End If

If fpt = 8 Then
 ptp = 3
 If ip <= 0.7 Then wr2$ = "SN. FLURRY"
 If ip > 0.7 Then wr2$ = "LIGHT SNOW"
 If ip > 1.32 Then wr2$ = "MOD. SNOW"
 If ip > 2.05 Then wr2$ = "HEAVY SNOW"
 If ws > 20 And te < 266 And ip > 1.5 Then wr2$ = "BLIZZARD"
 If ip = 0 Then
  If prd > 0.1 Or prs > 0.1 Then wr2$ = "CHNC. SNOW"
  If prd > 0.3 Or prs > 0.3 Then wr2$ = "PROB. SNOW"
 End If
End If

If fpt = 9 Then
 ptp = 2
 wr2$ = "SNOW/RAIN"
 If ip < 1.5 Then wr2$ = "LT. SNW/RN"
 If ip > 2.3 Then wr2$ = "HVY.SNW/RN"
 If ip = 0 Then
  If prd > 0.1 Or prs > 0.1 Then wr2$ = "CH. SNW/RN"
  If prd > 0.3 Or prs > 0.3 Then wr2$ = "PR. SNW/RN"
 End If
End If

If fpt = 10 Then
 ptp = 2
 wr2$ = "RAIN/SNOW"
 If ip < 1.8 Then wr2$ = "LT. RN/SNW"
 If ip > 2.6 Then wr2$ = "HVY.RN/SNW"
 If ip = 0 Then
  If prd > 0.1 Or prs > 0.1 Then wr2$ = "CH. RN/SNW"
  If prd > 0.3 Or prs > 0.3 Then wr2$ = "PR. RN/SNW"
 End If
End If

750 If ip > 0 Then pef

If Len(wr$) < 10 Then
 Do: wr$ = wr$ & " ": Loop Until Len(wr$) = 10
End If
wr$ = wr$ & wr2$ & "  "

End Sub

======================================================================================

List of plaintext.txt words or terms:

WXSIM text forecast for
initialized at
feet
meters
above sea level.
above ground.
Rest of tonight
Low 
Minimum freezing level
Minimum snow level
High
Maximum freezing level
Maximum snow level
night
Today
Tonight
This afternoon
in the morning
in the afternoon
after midnight
, then
, becoming
, but temperatures falling in the afternoon.
, but temperatures rising after midnight.
around
, gusting to
, occasionally gusting to
near calm
Breezy
Windy
Very windy
cold
cool
relatively cool
very cold
unusually cold
unusually cool
extremely cold
exceptionally cold
exceptionally cool
near record cold
near record low temperatures
warm
mild
relatively mild
unusually warm
unusually mild
exceptionally warm
exceptionally mild
near record warmth
near record cool temperatures
with
and
hot
very hot 
extremely hot
exceptionally hot
unusually hot
near record heat
Wind chill ranging from
to
Wind chill as low as
Wind chill around
scattered light frost possible.
areas of light frost likely.
light to moderate frost.
moderate to heavy frost.
Heat index
Humidex
up to
UV index up to
Chance of precipitation
percent.
Chance of precipitation less than 20 percent.
Chance of precipitation near 100 percent.
Precipitation mostly
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.
Precipitation (liquid equivalent) mostly
Snow
Ice (on ground)
Snow or ice (on ground)
less than a tenth of an inch.
around a tenth of an inch.
less than a quarter of an inch.
around a quarter of an inch.
between a quarter and half an inch.
around half an inch.
between half an inch and one inch.
around an inch.
between 1 and 2 inches.
around 2 inches.
between 2 and 3 inches.
around 3 inches.
between 3 and 5 inches.
between 4 and 6 inches.
over six inches.
No
accumulation expected.
Little or no
accumulation about a quarter inch.
accumulation about half an inch.
accumulation about an inch.
accumulation 1 to 2 inches.
accumulation around 2 inches.
accumulation 2 to 3 inches.
accumulation 2 to 4 inches.
accumulation 3 to 5 inches.
accumulation 4 to 6 inches.
accumulation 5 to 8 inches.
accumulation 6 to 10 inches.
accumulation 8 to 12 inches.
accumulation 12 to 16 inches.
accumulation 15 to 20 inches.
accumulation 20 inches or more.
Above-ground freezing rain accumulation up to
inches.
Little if any freezing rain accumulation.
less than 2 mm.
around 2 mm.
between 2 and 5 mm.
around 5 mm.
between 5 and 10 mm.
around 10 mm.
between 10 and 20 mm.
around 20 mm.
between 20 and 30 mm.
around 30 mm.
between 30 and 50 mm.
between 40 and 60 mm.
over 60 mm.
accumulation less than one cm.
accumulation about a cm.
accumulation 1 to 2 cm.
accumulation about 2 cm.
accumulation 2 to 3 cm.
accumulation 2 to 4 cm.
accumulation 3 to 5 cm.
accumulation 4 to 6 cm.
accumulation 5 to 8 cm.
accumulation 6 to 10 cm.
accumulation 8 to 12 cm.
accumulation 12 to 16 cm.
accumulation 15 to 20 cm.
accumulation 20 to 30 cm.
accumulation 30 to 40 cm.
accumulation 40 to 50 cm.
accumulation 50 cm or more.
mm.
clear
sunny
mostly clear
fair
mostly sunny
fair to partly cloudy
partly to mostly sunny
partly cloudy
partly to mostly cloudy
mostly cloudy 
mostly cloudy to cloudy
cloudy
dense overcast
clear except for a few wispy clouds
sunny, with just a few wispy clouds
mostly clear, with just a few high thin clouds
sunny, with just a few high thin clouds
fair, but some high thin clouds
mostly sunny, but some high thin clouds
mostly fair, but some high cloudiness
partly to mostly sunny, but some high cloudiness
patchy light fog
light to moderate fog
moderate fog
moderate to dense fog
dense fog
a mix of
a slight chance of
a chance of
likely
very likely
north
north-northeast
northeast
east-northeast
east
east-southeast
southeast
south-southeast
south
south-southwest
southwest
west-southwest
west
west-northwest
northwest
north-northwest
 * THIS FORECAST WAS MADE IN AUTOMATED MODE AND MAY BE LESS ACCURATE THAN OTHERWISE *
rain
freezing rain 
sleet
snow