559
FNUS73 KLSX 120753
FWSLSX
SPOT FORECAST FOR CHEMICAL FIRE...ST. CLAIR EMA
NATIONAL WEATHER SERVICE SAINT LOUIS MO
253 AM CDT WED AUG 12 2026
FORECAST IS BASED ON FORECAST START TIME OF 0300 CDT ON AUGUST 12.
IF CONDITIONS BECOME UNREPRESENTATIVE, CONTACT THE
NATIONAL WEATHER SERVICE.
DISCUSSION
LIGHT SOUTHERLY WINDS WILL MAKE DISPERSION OF ANY CHEMICALS VERY
DIFFICULT, ESPECIALLY WITH A STRONG INVERSION LIMITING VERTICAL
MIXING THROUGH THE REST OF TONIGHT. AFTER SUNRISE, DAYTIME HEATING
WILL CAUSE VERTICAL MIXING TO GROW, WHICH WILL ALLOW ANY CHEMICAL
TO DISPERSE A BIT MORE EFFICIENTLY THROUGH THE MORNING INTO THE
AFTERNOON. WINDS ALSO BECOME MORE SOUTHWESTERLY AND STRENGTHEN A
BIT. RAIN CHANCES INCREASE TO ABOUT 20% THIS AFTERNOON, WITH A
FEW THUNDERSTORMS THAT THREATEN STRONG WINDS AND HEAVY DOWNPOURS.
IF AN UPDATE IS NEEDED TO THIS FORECAST, PLEASE CALL 636-447-1887
AND SPEAK WITH A METEOROLOGIST.
REST OF TONIGHT
SKY/WEATHER.........PARTLY CLOUDY (20-30 PERCENT).
CWR.................0 PERCENT.
CHANCE OF THUNDER...0 PERCENT.
TEMPERATURE.........80 AT FORECAST START...MIN 79.
RH..................74 PERCENT AT FORECAST START...MAX 77 PERCENT.
SURFACE WINDS (MPH).SOUTHWEST WINDS AROUND 6 MPH.
MIXING HEIGHT.......500 FT AGL AT FORECAST START...OTHERWISE MIN
400 FT AGL.
TIME (CDT) 3AM 4AM 5AM 6AM 7AM 8AM 9AM 10A 11A 12P 1PM 2PM
SKY (%).........25 27 26 31 33 41 32 46 53 45 47 36
WEATHER COV..... SCH SCH SCH
WEATHER TYPE.... RW RW RW
TSTM COV........ SCH SCH SCH
CWR.............0 0 0 10 10 10 10 10 10 10 10 10
CHC OF THDR (%).0 0 0 0 0 0 0 0 0 20 20 20
TEMP............80 79 80 79 79 82 85 88 91 92 93 94
RH..............74 77 74 74 77 74 70 66 62 62 60 58
SURFACE WND DIR.SW SW SW SW SW SW SW W W SW SW SW
SURFACE WND SPD.6 6 6 5 5 6 6 7 7 7 7 7
SURFACE WND GST.12 12 10 9 9 9 10 12 12 12 12 10
MIX HGT (KFT)...0.5 0.4 0.5 0.5 0.7 0.7 1.2 1.7 2.0 2.7 4.3 5.2
TODAY
SKY/WEATHER.........MOSTLY SUNNY (35-45 PERCENT). SLIGHT CHANCE OF
SHOWERS AND THUNDERSTORMS IN THE AFTERNOON.
CWR.................11 PERCENT.
CHANCE OF THUNDER...18 PERCENT.
TEMPERATURE.........MAX 97.
RH..................MIN 55 PERCENT.
SURFACE WINDS (MPH).LIGHT WINDS BECOMING SOUTHWEST 6 TO 7 MPH EARLY
IN THE MORNING.
MIXING HEIGHT.......MAX 5600 FT AGL.
TONIGHT
SKY/WEATHER.........PARTLY CLOUDY (30-40 PERCENT) THEN BECOMING
MOSTLY CLOUDY (55-65 PERCENT) THEN BECOMING
PARTLY CLOUDY (45-55 PERCENT) THEN BECOMING
MOSTLY CLOUDY (45-55 PERCENT). SLIGHT CHANCE OF
SHOWERS AND THUNDERSTORMS EARLY IN THE EVENING.
SLIGHT CHANCE OF SHOWERS AND THUNDERSTORMS
OVERNIGHT, THEN CHANCE OF SHOWERS AND
THUNDERSTORMS AFTER 3 AM.
CWR.................11 PERCENT.
CHANCE OF THUNDER...36 PERCENT.
TEMPERATURE.........MIN 77.
RH..................MAX 82 PERCENT.
SURFACE WINDS (MPH).SOUTH WINDS AROUND 6 MPH EARLY IN THE EVENING
SHIFTING TO THE EAST, THEN SHIFTING TO THE
SOUTHEAST IN THE LATE EVENING AND OVERNIGHT
BECOMING LIGHT.
MIXING HEIGHT.......MIN 500 FT AGL.
FORECASTER...MRB
REQUESTED BY...BRYAN WHITAKER
TYPE OF REQUEST...HAZMAT
.TAG 2619502.0/LSX
.DELDT 08/12/26
.FORMATTERVERSION 2.0.0
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