673  
FNUS73 KLSX 201214  
FWSLSX  
 
SPOT FORECAST FOR SIOUX PASSAGE UNITS...ST. LOUIS COUNTY PARKS FORESTRY  
NATIONAL WEATHER SERVICE SAINT LOUIS MO  
614 AM CST WED JAN 20 2021  
 
FORECAST IS BASED ON IGNITION TIME OF 1000 CST ON JANUARY 20.  
IF CONDITIONS BECOME UNREPRESENTATIVE, CONTACT THE  
NATIONAL WEATHER SERVICE.  
   
DISCUSSION
 
 
WARMER TEMPERATURES ARE EXPECTED TODAY WITH SOUTHWEST WINDS GUSTING TO  
NEAR 20 MPH. A DRY COLD FRONT WILL MOVE THROUGH THE REGION THURSDAY  
NIGHT, WHICH WILL BRING TEMPERATURES BACK DOWN TO NEAR NORMAL FOR FRIDAY.  
 
   
REST OF TODAY
 
 
SKY/WEATHER.........SUNNY (15-25 PERCENT).  
TEMPERATURE.........32 AT IGNITION...MAX 46.  
RH..................63 PERCENT AT IGNITION...MIN 49 PERCENT.  
WIND (20 FT)........WINDS SOUTH AT 5 MPH AT IGNITION...OTHERWISE  
SOUTH WINDS 5 TO 10 MPH.  
EYE LEVEL WINDS.....2 TO 4 MPH, USING AN ADJUSTMENT FACTOR OF 0.4.  
HAINES INDEX........4 OR LOW POTENTIAL FOR LARGE PLUME DOMINATED  
FIRE GROWTH AT IGNITION...MAX 4.  
MIXING HEIGHT.......1300 FT AGL AT IGNITION...OTHERWISE MAX 2200 FT  
AGL.  
TRANSPORT WINDS.....SOUTHWEST 6 TO 10 MPH INCREASING TO SOUTH 16 TO  
20 MPH IN THE AFTERNOON.  
SMOKE DISPERSAL.....POOR /1040 M/S-M/ AT IGNITION. MAX...MARGINAL  
/5590 M/S-M/.  
 
TIME (CST) 10 AM NOON 2 PM 4 PM 6 PM 8 PM  
SKY (%).........3 6 12 17 38 55  
WEATHER COV.....  
WEATHER TYPE....NONE NONE NONE NONE NONE NONE  
TSTM COV........  
TEMP............32 39 45 46 41 40  
RH..............63 54 49 49 62 62  
20 FT WIND......S 5 S 8 S 9 S 9 S 9 SW 9  
20 FT WIND GUST.9 13 16 17 14 15  
EYE LEVEL WIND..S 2 S 4 S 4 S 4 S 4 SW 4  
EYE LVL WND GST.4 6 7 8 6 7  
MIX HGT (KFT)...1.3 1.6 2.2 1.2 0.9 1.2  
TRANSPORT WIND..SW 6 SW 10 SW 18 S 17 S 20 SW 22  
HAINES INDEX....4 4 4 4 4 4  
VRATE KT-FT/1K..7 15 36 18 15 23  
VENTRATE CAT....POOR POOR POOR POOR POOR POOR  
   
THURSDAY
 
 
SKY/WEATHER.........SUNNY (5-15 PERCENT).  
TEMPERATURE.........MAX 51.  
RH..................MIN 44 PERCENT.  
WIND (20 FT)........WEST WINDS 5 TO 8 MPH.  
EYE LEVEL WINDS.....2 TO 3 MPH, WITH AN ADJUSTMENT FACTOR OF 0.4.  
HAINES INDEX........3 TO 5 OR VERY LOW TO MODERATE POTENTIAL FOR  
LARGE PLUME DOMINATED FIRE GROWTH.  
MIXING HEIGHT.......MAX 2800 FT AGL.  
TRANSPORT WINDS.....WEST 15 TO 20 MPH.  
SMOKE DISPERSAL.....POOR (1040 M/S-M) EARLY IN THE MORNING  
INCREASING TO FAIR MAX (7040 M/S-M) IN THE  
AFTERNOON.  
 

 
 
FORECASTER...MRM  
REQUESTED BY...JASON PRATTE  
TYPE OF REQUEST...PRESCRIBED  
.TAG 2100903.0/LSX  
.DELDT 01/20/21  
.FORMATTERVERSION 1.0.26  
 
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