784
FNUS73 KOAX 181157
FWSOAX
SPOT FORECAST FOR WILLOW SLOUGH...IOWA DNR
NATIONAL WEATHER SERVICE OMAHA/VALLEY NE
657 AM CDT WED MAR 18 2026
FORECAST IS BASED ON IGNITION TIME OF 1000 CDT ON MARCH 18.
IF CONDITIONS BECOME UNREPRESENTATIVE, CONTACT THE NATIONAL WEATHER
SERVICE.
DISCUSSION
A WIND SHIFT HAS ARRIVED TO NORTHEASTERN MILLS COUNTY THIS
MORNING, WITH LIGHTER WESTERLY WINDS EXPECTED TODAY COMPARED TO
THE GUSTIER SOUTHERLIES FROM YESTERDAY. TEMPS IN THE TWENTIES TO
START THE DAY AT 8 CDT WILL TRANSLATE TO HUMIDITY VALUES OF
75-80% AND MIXING HEIGHTS OF 275 FT AGL WHILE CALM TO 5 MPH WINDS
OUT OF THE WEST BEGIN TO TAKE HOLD. BY NOON, WE'LL BE IN THE
MID 50S, WITH HUMIDITY VALUES NEAR 45-50%, WINDS 10 TO 15 MPH, AND
INCREASED MIXING HEIGHTS TO 1000 FT AGL. CONDITIONS BECOME MOST
CONDUCIVE TO BURNING BY 4 PM, WITH TEMPS NEAR 70, HUMIDITY VALUES
30-35%, WINDS OUT OF THE WEST OF 10-20 MPH, AND MIXING HEIGHTS OF
3000-3500 FT AGL (RESULTING IN FAIR SMOKE DISPERSAL). IF WE END
UP A BIT WARMER THIS AFTERNOON COMPARED TO THE FORECAST, RH VALUES
COULD REACH AS LOW AS 25%.
TEMPERATURES ON THURSDAY WILL BE MAINLY IN THE 70S WITH LOWEST
RELATIVE HUMIDITY RANGING FROM 35 TO 40 PERCENT IN WESTERN IOWA.
WINDS WILL BE FROM THE NORTHWEST OR NORTH AT 5 TO 10 MPH. PEAK
MIXING HEIGHTS BETWEEN 2000 AND 4500 FT ARE FORECAST WITH FAIR TO
VERY GOOD SMOKE DISPERSAL.
STRONGEST POSSIBLE WIND SPEEDS ON DAY OF BURN: 20 MPH
LOWEST POSSIBLE RELATIVE HUMIDITY ON DAY OF BURN: 25 PERCENT
REST OF TODAY
SKY/WEATHER.........SUNNY (15-25 PERCENT).
MAX TEMPERATURE.....AROUND 68.
MIN HUMIDITY........39 PERCENT.
EYE LEVEL WINDS.....LIGHT WINDS BECOMING SOUTHWEST AROUND 4 MPH IN
THE AFTERNOON.
SURFACE WINDS (MPH).SOUTHWEST WINDS 6 TO 8 MPH.
WIND (20 FT)........WEST WINDS 5 TO 6 MPH.
MIXING HEIGHT.......3100 FT AGL.
TRANSPORT WINDS.....WEST 7 TO 12 MPH.
SMOKE DISPERSAL.....POOR (3000 KNOT-FT) EARLY IN THE MORNING
INCREASING TO FAIR (24400 KNOT-FT) IN THE
AFTERNOON.
GFDI................3.
TIME (CDT) 10A 11A 12P 1PM 2PM 3PM 4PM 5PM
SKY (%).........3 23 32 18 11 13 12 17
WEATHER COV.....
WEATHER TYPE....
TSTM COV........
TEMP............40 48 54 60 65 67 68 68
RH..............71 64 60 52 45 41 40 39
20 FT WIND DIR..NW NW W W W SW SW SW
20 FT WIND SPD..3 3 5 5 5 5 6 5
20 FT WIND GUST.5 6 6 6 7 7 10 7
EYE LVL WND DIR.NW NW W W W SW SW SW
EYE LVL WND SPD.2 2 4 4 4 4 4 4
EYE LVL WND GST.4 4 5 5 5 7 5
SURFACE WND DIR.NW NW W W W SW SW SW
SURFACE WND SPD.4 4 6 6 6 6 8 6
SURFACE WND GST.6 7 7 8 9 9 12 9
MIX HGT (KFT)...0.5 0.6 1.1 1.2 1.5 2.1 2.4 3.1
TRANSP WIND DIR.NW NW NW W W W W W
TRANSP WIND SPD.8 7 7 7 8 10 12 12
GFDI............1 1 2 2 3 3 4 3
SDSPL KT-FT/10004 4 5 7 14 21 24 20
TONIGHT
SKY/WEATHER.........MOSTLY CLEAR (20-30 PERCENT) THEN BECOMING
MOSTLY CLOUDY (60-70 PERCENT) THEN BECOMING
PARTLY CLOUDY (30-40 PERCENT).
MIN TEMPERATURE.....AROUND 38.
MAX HUMIDITY........100 PERCENT.
EYE LEVEL WINDS.....SOUTHWEST WINDS AROUND 4 MPH IN THE EVENING AND
OVERNIGHT BECOMING LIGHT.
SURFACE WINDS (MPH).SOUTHWEST WINDS AROUND 6 MPH IN THE EVENING AND
OVERNIGHT BECOMING LIGHT.
WIND (20 FT)........WEST WINDS AROUND 5 MPH SHIFTING TO THE SOUTH
EARLY IN THE EVENING, THEN BECOMING LIGHT AFTER
3 AM.
MIXING HEIGHT.......300 FT AGL.
TRANSPORT WINDS.....SOUTHWEST 8 TO 9 MPH BECOMING 7 TO 10 MPH IN
THE LATE EVENING AND OVERNIGHT, THEN SHIFTING
TO THE WEST 7 TO 9 MPH AFTER 3 AM.
SMOKE DISPERSAL.....POOR (2100 KNOT-FT).
GFDI................2.
TIME (CDT) 6PM 7PM 8PM 9PM 10P 11P MID 1AM 2AM 3AM 4AM 5AM
SKY (%).........19 29 54 68 64 71 82 65 51 40 35 32
WEATHER COV.....
WEATHER TYPE....
TSTM COV........
TEMP............68 64 61 56 54 52 51 49 48 46 45 43
RH..............41 46 52 64 65 71 72 75 75 82 85 91
20 FT WIND DIR..SW SW S S S S S SW SW W NW NW
20 FT WIND SPD..5 5 5 5 5 5 5 5 5 4 4 4
20 FT WIND GUST.6 6
EYE LVL WND DIR.SW SW S S S S S SW SW W NW NW
EYE LVL WND SPD.4 4 4 4 4 4 4 4 4 3 3 3
EYE LVL WND GST.
SURFACE WND DIR.SW SW S S S S S SW SW W NW NW
SURFACE WND SPD.6 6 6 6 6 6 6 6 6 5 5 5
SURFACE WND GST.7 7
MIX HGT (KFT)...0.9 0.6 0.5 0.5 0.5 0.4 0.4 0.4 0.4 0.4 0.3 0.4
TRANSP WIND DIR.W SW SW S S S SW SW SW W W NW
TRANSP WIND SPD.9 9 8 7 9 10 10 9 9 7 8 9
GFDI............3 2 2 1 1 1 1 1 1 1 1 1
SDSPL KT-FT/100012 5 3 3 4 4 4 4 3 3 3 3
THURSDAY
SKY/WEATHER.........MOSTLY SUNNY (25-35 PERCENT).
MAX TEMPERATURE.....AROUND 72.
MIN HUMIDITY........44 PERCENT.
EYE LEVEL WINDS.....LIGHT WINDS BECOMING NORTHWEST AROUND 4 MPH.
SURFACE WINDS (MPH).LIGHT WINDS BECOMING NORTHWEST 6 TO 8 MPH.
WIND (20 FT)........LIGHT WINDS BECOMING NORTH 5 TO 7 MPH.
MIXING HEIGHT.......2900 FT AGL.
TRANSPORT WINDS.....NORTH 7 TO 12 MPH.
SMOKE DISPERSAL.....POOR (2500 KNOT-FT) EARLY IN THE MORNING
INCREASING TO FAIR (20900 KNOT-FT) IN THE
AFTERNOON.
GFDI................3.
TIME (CDT) 6AM 7AM 8AM 9AM 10A 11A 12P 1PM 2PM 3PM 4PM 5PM
SKY (%).........38 44 34 25 20 17 16 16 17 17 18 20
WEATHER COV.....
WEATHER TYPE....
TSTM COV........
TEMP............41 40 39 43 52 57 62 66 69 71 72 72
RH..............95 95 100 97 76 67 59 53 48 45 44 45
20 FT WIND DIR..NW NW N N N N N N N NW NW NW
20 FT WIND SPD..4 5 5 5 5 6 6 6 6 6 6 5
20 FT WIND GUST. 6 6 6 7 8 10 10 10 10 8 7
EYE LVL WND DIR.NW NW N N N N N N N NW NW NW
EYE LVL WND SPD.3 4 4 4 4 4 4 4 4 4 4 4
EYE LVL WND GST. 5 5 5 5 6 7 7 7 7 6 5
SURFACE WND DIR.NW NW N N N N N N N NW NW NW
SURFACE WND SPD.5 6 6 6 6 8 8 8 8 8 8 6
SURFACE WND GST. 8 8 8 9 10 12 12 12 12 10 9
MIX HGT (KFT)...0.4 0.4 0.4 0.5 0.8 1.0 1.5 1.9 2.4 2.8 2.9 2.3
TRANSP WIND DIR.NW N N N N N N N N N N NW
TRANSP WIND SPD.10 9 10 12 12 10 12 9 7 7 8 7
GFDI............1 1 1 1 1 2 3 3 4 4 4 3
SDSPL KT-FT/10003 4 5 6 8 11 13 15 19 21 21 15
FORECASTER...PETERSEN
REQUESTED BY...ZAC RIPPERGER
TYPE OF REQUEST...PRESCRIBED
.TAG 2606040.0/OAX
.DELDT 03/18/26
.FORMATTERVERSION 2.0.0
.EMAIL ZAC.RIPPERGER@DNR.IOWA.GOV
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