890  
FNUS73 KLOT 312050  
FWSLOT  
 
SPOT FORECAST FOR CHICAGO ROAD RX...USFS  
NATIONAL WEATHER SERVICE CHICAGO IL  
250 PM CST WED JAN 31 2018  
 
FORECAST IS BASED ON IGNITION TIME OF 1500 CST ON JANUARY 31.  
IF CONDITIONS BECOME UNREPRESENTATIVE...CONTACT THE NATIONAL WEATHER  
SERVICE.  
 
PLEASE CONTACT OUR OFFICE AT (815) 834-0666, IF YOU HAVE QUESTIONS  
OR CONCERNS WITH THIS FORECAST.  
   
DISCUSSION
 
 
A STRONG COLD FRONT WILL MOVE ACROSS THE AREA EARLY THURSDAY  
MORNING, RESULTING IN A WIND SHIFT FROM LIGHT WESTERLY TO  
MODERATELY STRONG AND GUSTY FROM THE NORTHWEST. SOME CLOUDINESS IS  
EXPECTED BEHIND THE FRONT, BUT SKIES SHOULD BECOME MOSTLY SUNNY  
BY AFTERNOON. TEMPERATURES WILL BE NEARLY STEADY THROUGH THE DAY  
THURSDAY WITH SLOWLY FALLING DEWPOINTS LEADING TO FALLING RELATIVE  
HUMIDITY LEVELS. MIXING WILL BE ABOVE 1700 FT THROUGH THE DAY ONCE  
THE COLD FRONT MOVES THROUGH EARLY IN THE MORNING.  
   
REST OF TODAY
 
 
SKY/WEATHER.........MOSTLY CLOUDY.  
TEMPERATURE.........43 AT IGNITION...MAX 43.  
RH..................57 PERCENT AT IGNITION...MIN 52 PERCENT.  
WIND (20 FT)........WINDS WEST AT 11 MPH AT IGNITION...OTHERWISE  
WEST WINDS 7 TO 12 MPH.  
CHANCE OF PCPN......10 PERCENT.  
LAL.................NO TSTMS.  
MIXING HEIGHT.......2100 FT AGL AT IGNITION...OTHERWISE 900-2100 FT  
AGL.  
TRANSPORT WINDS.....WEST 18 TO 23 MPH.  
MIXING TEMP 1700FT..N/A.  
SMOKE DISPERSAL.....GOOD /40700 KNOT-FT/ AT IGNITION. MAX...GOOD  
/40700 KNOT-FT/.  
 
TIME (CST) 3PM 4PM 5PM  
SKY (%).........87 87 86  
WEATHER COV.....  
WEATHER TYPE....  
TEMP............43 42 40  
RH..............57 60 64  
20 FT WIND DIR..W W W  
20 FT WIND SPD..11 8 6  
20 FT WIND GUST.20 15 15  
MIX HGT (KFT)...2.1 1.5 0.9  
TRANSP WIND DIR.260 260 270  
TRANSP WIND SPD.23 21 18  
CHC OF PCPN (%).0 0 10  
LAL.............1 1 1  
VRATE KT-FT/100041 27 15  
   
TONIGHT
 
 
SKY/WEATHER.........MOSTLY CLOUDY THEN BECOMING PARTLY CLOUDY THEN  
BECOMING MOSTLY CLOUDY.  
TEMPERATURE.........MIN 23.  
RH..................MAX 88 PERCENT.  
WIND (20 FT)........WEST WINDS 5 TO 6 MPH EARLY IN THE EVENING  
BECOMING LIGHT, THEN BECOMING WEST 5 TO 7 MPH  
EARLY IN THE MORNING.  
CHANCE OF PCPN......0 PERCENT.  
LAL.................NO TSTMS.  
MIXING HEIGHT.......100-300 FT AGL.  
TRANSPORT WINDS.....WEST 8 TO 16 MPH DECREASING TO 3 TO 7 MPH IN  
THE LATE EVENING AND OVERNIGHT.  
MIXING TEMP 1700FT..N/A.  
SMOKE DISPERSAL.....POOR (300 KNOT-FT).  
 
TIME (CST) 6PM 7PM 8PM 9PM 10P 11P MID 1AM 2AM 3AM 4AM 5AM  
SKY (%).........86 85 84 83 83 83 83 74 65 75 74 73  
WEATHER COV.....  
WEATHER TYPE....  
TEMP............37 36 35 34 32 31 30 30 29 29 28 27  
RH..............72 79 82 85 88 88 88 85 85 85 85 85  
20 FT WIND DIR..W W W W W W W W SW SW W W  
20 FT WIND SPD..6 5 4 4 4 4 4 4 4 4 5 6  
20 FT WIND GUST.10 10 5 5 5 5 5 5 5 10 10 10  
MIX HGT (KFT)...0.3 0.2 0.2 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1  
TRANSP WIND DIR.270 270 270 260 260 260 260 260 250 240 250 270  
TRANSP WIND SPD.16 13 8 5 3 3 5 5 5 5 6 7  
CHC OF PCPN (%).0 0 0 0 0 0 0 0 0 0 0 0  
LAL.............1 1 1 1 1 1 1 1 1 1 1 1  
VRATE KT-FT/10004 3 1 0 0 0 0 0 0 0 1 1  
   
THURSDAY
 
 
SKY/WEATHER.........MOSTLY CLOUDY THEN BECOMING PARTLY CLOUDY THEN  
BECOMING MOSTLY SUNNY.  
TEMPERATURE.........MAX 25.  
RH..................MIN 37 PERCENT.  
WIND (20 FT)........NORTHWEST WINDS 12 TO 16 MPH. GUSTS UP TO 30 MPH  
IN THE LATE MORNING AND AFTERNOON.  
CHANCE OF PCPN......0 PERCENT.  
LAL.................NO TSTMS.  
MIXING HEIGHT.......100-1900 FT AGL INCREASING TO 2300-3900 FT AGL  
IN THE LATE MORNING AND AFTERNOON.  
TRANSPORT WINDS.....WEST 10 TO 16 MPH INCREASING TO NORTHWEST 22 TO  
26 MPH IN THE MORNING.  
MIXING TEMP 1700FT..19.  
SMOKE DISPERSAL.....POOR TO GOOD (900-43400 KNOT-FT) INCREASING TO  
GOOD TO EXCELLENT (52200-77500 KNOT-FT) IN THE  
LATE MORNING AND AFTERNOON.  
 
TIME (CST) 6AM 7AM 8AM 9AM 10A 11A 12P 1PM 2PM 3PM 4PM 5PM  
SKY (%).........72 61 50 38 30 21 13 10 7 4 6 7  
WEATHER COV.....  
WEATHER TYPE....  
TEMP............27 24 23 22 22 22 21 21 20 20 19 17  
RH..............81 77 68 62 52 45 43 39 39 37 37 40  
20 FT WIND DIR..W W NW NW NW NW NW NW NW NW NW NW  
20 FT WIND SPD..8 10 13 15 16 16 15 15 15 15 14 14  
20 FT WIND GUST.15 20 25 25 30 25 25 25 25 25 25 20  
MIX HGT (KFT)...0.1 0.7 1.7 1.9 2.3 2.6 3.0 3.3 3.6 3.9 3.6 3.3  
TRANSP WIND DIR.280 290 310 320 320 310 310 310 310 310 310 310  
TRANSP WIND SPD.10 16 22 26 26 24 23 23 23 23 23 23  
CHC OF PCPN (%).0 0 0 0 0 0 0 0 0 0 0 0  
LAL.............1 1 1 1 1 1 1 1 1 1 1 1  
VRATE KT-FT/10001 10 25 43 52 57 59 65 71 78 72 67  
 

 
FORECASTER...IZZI  
REQUESTED BY...JESSE HOH  
TYPE OF REQUEST...PRESCRIBED  
.TAG 1801311.0/LOT  
 
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