939  
FXUS63 KILX 221729  
AFDILX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE LINCOLN IL  
1229 PM CDT FRI SEP 22 2017  
   
UPDATE
 
 
ISSUED AT 1048 AM CDT FRI SEP 22 2017  
 
HOT AND MUGGY WEATHER ACROSS THE MIDWEST CONTINUES AS HIGH  
PRESSURE DOMINATES THE EASTERN HALF OF THE US. SOUTHERLY WINDS  
AND PLENTY OF SUNSHINE WILL KEEP THE HOT CONDITIONS IN PLACE  
THROUGH THE FIRST WEEKEND OF AUTUMN. SOME MINOR CU DEVELOPMENT  
POSSIBLE TODAY, OTHERWISE IT IS A VERY QUIET FORECAST. NO MAJOR  
UPDATES TO THE FORECAST ANTICIPATED AT THIS TIME.  
 

 
   
SHORT TERM
 
(TODAY AND TONIGHT)  
ISSUED AT 207 AM CDT FRI SEP 22 2017  
 
MAIN STORY FOR THIS FIRST DAY OF FALL REMAINS WITH THE HEAT.  
AN UPPER LEVEL RIDGE REMAINS FIRMLY IN PLACE OVER THE MIDWEST  
THIS MORNING, AND 850 MB TEMPERATURES ARE ABOVE THE 90TH  
PERCENTILE FOR THIS TIME OF YEAR. TEMPERATURES LIKELY TO AGAIN  
REACH INTO THE 92-94 DEGREE RANGE IN MUCH OF THE FORECAST AREA,  
WITH A FEW RECORD HIGHS POSSIBLE. CU-RULE SUGGESTS SOME SCATTERED  
CUMULUS DEVELOPMENT OVER MAINLY THE EAST HALF OF THE FORECAST  
AREA. SEVERAL OF THE HIGH-RESOLUTION MODELS ARE HINTING AT SOME  
ISOLATED SHOWERS FORMING IN THIS AREA BY EARLY AFTERNOON. HOWEVER,  
GIVEN THE STRENGTH OF THE RIDGE AND LITTLE IN THE WAY OF FORCING,  
WILL KEEP THE FORECAST DRY FOR NOW.  
   
LONG TERM
 
(SATURDAY THROUGH THURSDAY)  
ISSUED AT 207 AM CDT FRI SEP 22 2017  
 
NO REAL CHANGE IN THE FORECAST PHILOSOPHY THROUGH THIS PERIOD.  
THROUGH EARLY NEXT WEEK, THE STRONG UPPER RIDGE OVER THE EASTERN  
U.S. REMAINS THE DRIVING FORCE, WITH HIGH TEMPERATURES REMAINING  
IN NEAR RECORD TERRITORY IN THE LOWER 90S. TEMPERATURES START  
EASING OFF A BIT ON TUESDAY WITH MORE CLOUD COVER, BUT I WOULD NOT  
BE SURPRISED TO SEE THAT DAY TRENDING UPWARD AS WELL.  
 
UPPER PATTERN FINALLY STARTS TO BREAK DOWN AROUND MIDWEEK, AS A  
STRONG SHORTWAVE EJECTS NORTHEAST OUT OF THE ROCKIES INTO THE  
UPPER MISSISSIPPI VALLEY. MAIN QUESTION REMAINS WITH THE SPEED OF  
THE COLD FRONT PASSING THROUGH ILLINOIS. THE ECMWF FADES OUT ANY  
ASSOCIATED RAINFALL AS IT PASSES TUESDAY EVENING, WHILE THE GFS  
KEEPS SHOWERS GOING WITH A WEDNESDAY PASSAGE. THE CANADIAN MODEL  
IS THE ODD ONE OUT, HOLDING THE RIDGE MUCH LONGER UNTIL THURSDAY.  
IN ANY EVENT, RAIN CHANCES ARE NOT ESPECIALLY HIGH, BUT THE  
HIGHLIGHT WILL BE A SIGNIFICANT COOLDOWN.  
 

 
   
AVIATION
 
(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON)  
ISSUED AT 1229 PM CDT FRI SEP 22 2017  
 
VFR THROUGHOUT FORECAST. SOUTHERLY WINDS DOMINATE...WITH SOME  
MORE VARIABILITY IN CMI/DEC/BMI UNDER LESS OF A PRESSURE GRADIENT.  
FEW CU TODAY, DISSIPATING AT SUNSET, THEN FEW/SCT CIRRUS. WINDS  
STILL LIGHT AND SOUTHERLY OVERNIGHT, THOUGH SOME VARIABILITY WILL  
REMAIN POSSIBLE AS THE INVERSION SETS UP. SOME PATCHY VISIBILITY  
DROPS WILL ALSO BE POSSIBLE AS HAVE BEEN FOR THE LAST FEW NIGHTS,  
BUT NOTHING WIDESPREAD EXPECTED, AND CERTAINLY NOT ENOUGH TO DROP  
FLIGHT CATEGORY.  
 

 
   
CLIMATE
 
 
ISSUED AT 200 AM CDT FRI SEP 22 2017  
 
RECORD HIGHS THROUGH THE WEEKEND:  
 
LOCATION FRI SAT SUN  
-------- ------- ------- -------  
BLOOMINGTON 94/1930 92/1937 94/1933  
CHAMPAIGN 95/1891 94/1891 94/1891  
CHARLESTON 95/2005 93/2010 93/1933  
DECATUR 94/2005 92/2007 93/1933  
GALESBURG 92/1988 89/1937 90/2007  
OLNEY 96/2010 94/1960 94/2010  
PEORIA 93/1930 92/1937 92/2007  
SPRINGFIELD 95/2005 93/2007 93/2007  
 

 
   
ILX WATCHES/WARNINGS/ADVISORIES
 
 
NONE.  

 
 

 
 
UPDATE...HJS  
SHORT TERM...GEELHART  
LONG TERM...GEELHART  
AVIATION...HJS  
CLIMATE...GEELHART  
 
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