694
FNUS73 KLSX 212235
FWSLSX
SPOT FORECAST FOR PLANK HOLLOW RXB...MISSOURI DEPT OF CONSERVATION
NATIONAL WEATHER SERVICE SAINT LOUIS MO
435 PM CST WED JAN 21 2026
FORECAST IS BASED ON IGNITION TIME OF 1700 CST ON JANUARY 21.
IF CONDITIONS BECOME UNREPRESENTATIVE, CONTACT THE
NATIONAL WEATHER SERVICE.
DISCUSSION
SOUTHWESTERLY SURFACE WINDS ARE EXPECTED TO VEER OUT OF THE NORTHWEST
THIS EVENING BY 9 P.M. TEMPERATURES START OUT IN THE LOW TO MID-40S,
COOLING TO THE 20S BY MIDNIGHT. INVERSION HEIGHTS WILL REMAIN VERY LOW
(500-1000 FEET OR LOWER) THIS EVENING AND STRENGTHENS WITH THE LOSS OF
SURFACE HEATING. THIS WILL COUPLE WITH POOR VENTILATION RATES, RESULTING
IN POOR SMOKE DISPERSION THAT REMAINS SLIGHTLY OFF THE SURFACE AND
CONTINUES TO LOWER THROUGH LATE EVENING. RELATIVE HUMIDITY INCREASES
FROM AROUND 40 PERCENT NEAR SUNSET TO 60-70% THROUGH MIDNIGHT. MINIMUM
RH VALUES DROP TO AROUND 30 PERCENT THURSDAY WITH MIXING HEIGHT PEAKING
AROUND 3,000 FEET, BUT VENTILATION RATES REMAIN FAIR TO POOR WITH LIMITED
TIME FOR OPTIMAL BURNING FROM LATE MORNING TO EARLY AFTERNOON.
REST OF TODAY
SKY/WEATHER.........SUNNY (0-5 PERCENT).
TEMPERATURE.........43 AT IGNITION...MAX 50.
RH..................36 PERCENT AT IGNITION...MIN 31 PERCENT.
EYE LEVEL WINDS.....WEST WINDS 2-3 MPH. 0.4 FACTOR USED.
WIND (20 FT)........WINDS WEST AT 5 MPH AT IGNITION...OTHERWISE
WEST WINDS AROUND 5 MPH.
MIXING HEIGHT.......500 FT AGL AT IGNITION...OTHERWISE 500 FT AGL.
TRANSPORT WINDS.....WEST AROUND 9 MPH.
SMOKE DISPERSAL.....POOR /600 M/S-M/ AT IGNITION. MAX...POOR /600
M/S-M/.
TIME (CST) 5PM 6PM 7PM 8PM 9PM 10P 11P MID 1AM 2AM 3AM 4AM
SKY (%).........2 2 2 2 5 10 6 13 18 20 26 27
WEATHER COV.....
WEATHER TYPE....
TSTM COV........
TEMP............43 39 38 36 35 35 33 32 30 28 27 25
RH..............36 40 42 45 47 49 53 56 58 58 57 62
20 FT WIND DIR..W SW W W W W NW NW NW N N N
20 FT WIND SPD..5 4 5 5 5 5 6 6 5 4 3 2
20 FT WIND GUST.13 11 13 13 14 14 17 17 15 12 11 10
EYE LVL WND DIR.W SW W W W W NW NW NW N N N
EYE LVL WND SPD.2 2 2 2 2 2 3 3 2 2 1 1
EYE LVL WND GST.6 5 6 6 6 6 8 8 7 6 5 5
MIX HGT (KFT)...0.5 0.3 0.3 0.3 0.5 0.5 0.5 0.6 0.7 0.5 0.4 0.4
TRANSP WIND DIR.W W W W W NW NW N N N N N
TRANSP WIND SPD.9 12 13 14 14 16 17 15 12 10 9 8
VRATE KT-FT/1K..4 3 4 4 6 7 8 7 7 5 4 3
VENTRATE CAT....PR PR PR PR PR PR PR PR PR PR PR PR
TONIGHT
SKY/WEATHER.........MOSTLY CLEAR (15-25 PERCENT).
TEMPERATURE.........MIN 24.
RH..................MAX 65 PERCENT.
EYE LEVEL WINDS.....LIGHT WINDS INCREASING, BECOMING NORTHWESTERLY
AT 2-4 MPH, OCCASIONALLY GUSTING AROUND 15 MPH.
0.4 FACTOR USED.
WIND (20 FT)........LIGHT WINDS EARLY IN THE EVENING BECOMING WEST
AROUND 5 MPH, THEN SHIFTING TO THE NORTHWEST 5
TO 6 MPH WITH GUSTS TO AROUND 17 MPH LATE IN
THE EVENING BECOMING LIGHT.
MIXING HEIGHT.......MIN 300 FT AGL.
TRANSPORT WINDS.....WEST 12 TO 16 MPH SHIFTING TO THE NORTH AROUND
7 MPH EARLY IN THE MORNING.
SMOKE DISPERSAL.....POOR (380 M/S-M).
THURSDAY
SKY/WEATHER.........SUNNY (15-25 PERCENT).
TEMPERATURE.........MAX 42.
RH..................MIN 27 PERCENT.
EYE LEVEL WINDS.....LIGHT AND VARIABLE.
WIND (20 FT)........LIGHT WINDS.
MIXING HEIGHT.......MAX 2800 FT AGL.
TRANSPORT WINDS.....NORTH 3 TO 7 MPH SHIFTING TO THE WEST LATE IN
THE AFTERNOON, THEN SHIFTING TO THE NORTHEAST
AROUND 3 MPH LATE IN THE AFTERNOON.
SMOKE DISPERSAL.....POOR (200 M/S-M).
FORECASTER...MAPLES
REQUESTED BY...MATTHEW PETER
TYPE OF REQUEST...PRESCRIBED
.TAG 2600831.0/LSX
.DELDT 01/21/26
.FORMATTERVERSION 2.0.0
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