598  
FXUS63 KILX 241747  
AFDILX  
 
AREA FORECAST DISCUSSION...UPDATED AVIATION  
NATIONAL WEATHER SERVICE LINCOLN IL  
1247 PM CDT WED JUL 24 2024  
   
KEY MESSAGES
 
 
- MARGINAL RISK (LEVEL 1 OUT OF 5) TODAY FOR MUCH OF CENTRAL  
ILLINOIS AS A COLD FRONT MAKES ITS WAY ACROSS THE REGION. MAIN  
HAZARD OF DAMAGING WIND GUSTS. 40-60% CHANCE OF SHOWERS AND  
THUNDERSTORMS THIS AFTERNOON.  
 
- HEAT RETURNS NEXT WEEK STARTING MONDAY. BY WEDNESDAY, THERE IS A  
40-60% CHANCE OF HEAT INDICES GREATER THAN 100 DEGREES.  
 

 
   
UPDATE
 
 
ISSUED AT 1024 AM CDT WED JUL 24 2024  
 
A COLD FRONT ORIENTED WEST TO EAST ACROSS THE STATE, TRAILING A  
SURFACE LOW OVER LAKE HURON, WILL BE THE MAIN WEATHER FEATURE  
TODAY AND TONIGHT AS IT EDGES SOUTHWARD THROUGH CENTRAL IL.  
CURRENTLY, A WIND SHIFT IS EVIDENT ROUGHLY ACROSS THE I-74  
CORRIDOR, WITH CLOUD COVER AND SCATTERED SHOWERS AND THUNDERSTORMS  
TO THE NORTH. CONVECTIVE ALLOWING MODELS (CAMS) DEPICT AROUND 2000  
J/KG SBCAPE DEVELOPING THROUGH THE AFTERNOON ALONG THE FRONT,  
COINCIDENT WITH 30-35 KT SFC-6KM BULK SHEAR, WHICH SHOULD BE  
SUFFICIENT FOR SCATTERED STRONG TO SEVERE THUNDERSTORMS THIS  
AFTERNOON AND EVENING BEFORE INSTABILITY SLOWLY WANES OVERNIGHT AS  
THE FRONT SLIPS INTO A LESS SHEARED AREA OVER SOUTHERN IL. SPC  
INDICATES A MARGINAL RISK OF SEVERE STORMS CONTAINING HAIL AND  
LOCALLY DAMAGING WINDS FROM AROUND JACKSONVILLE TO PARIS NORTHWARD  
TODAY. HEAVY RAIN POTENTIAL WILL ALSO BE A THREAT AS SLOW MOVING  
STORMS WITH STORM MOTION ALIGNED ALONG THE FRONT HAVE A TENDENCY  
FOR TRAINING, OR RECURRENT DEVELOPMENT ALONG THE SAME CORRIDORS.  
CAMS DEPICT ISOLATED 2-PLUS INCH RAINFALL ACCUMULATIONS, ALTHOUGH  
GENERAL EXPECTATION IS CLOSER TO A MEAN OF QUARTER TO HALF INCH  
RAINFALL DUE TO ISOLATED TO WIDELY SCATTERED NATURE OF THE  
STRONGER STORMS. OTHERWISE, TEMPERATURES LOOK TO RANGE FROM HIGHS  
IN THE LOWER 80S NORTH OF I-74 WHERE CLOUD COVER IS MORE  
PERSISTENT, TO UPPER 80S FROM I-70 SOUTHWARD WHERE CLEARER SKIES  
LAST LONGER INTO THE AFTERNOON. HAVE MADE ONLY MINIMAL CHANGES TO  
TODAYS HIGHS FROM THE OVERNIGHT FORECAST PACKAGE.  
 
37  
 

 
   
DISCUSSION
 
 
ISSUED AT 246 AM CDT WED JUL 24 2024  
 
GOOD MORNING, ILLINOIS! WE HAVE SOME AREAS OF DENSE FOG AGAIN THIS  
MORNING ACROSS PORTIONS OF CENTRAL AND SOUTHEASTERN ILLINOIS. THE  
FOG SHOULD START DISSIPATING AS THE SUN RISES. SMOKE FROM CANADIAN  
WILDFIRES WILL ALSO IMPACT THE REGION TODAY, RESULTING IN HAZY  
LOOKING SKIES AND REDUCE AIR QUALITY. AT TIMES, YOU MAY BE ABLE TO  
SMELL SMOKE. A COLD FRONT IS EXPECTED TO PASS THROUGH THIS  
AFTERNOON, BRINGING STORM CHANCES WITH IT. AFTER TODAY/TONIGHT,  
THERE IS A DRY PERIOD TO END THE WORK WEEK AS AS SURFACE HIGH SETS  
UP OVER THE GREAT LAKE REGION. MORE CHANCES FOR PRECIPITATION MOVE  
IN SUNDAY AND LINGER INTO THE NEW WEEK.  
 
THE STORMS TODAY DO HAVE THE POTENTIAL TO BE STRONG TO SEVERE, AND  
PRODUCE HEAVY RAINFALL. MUCAPE VALUES OF 1500-2500 J/KG, BULK SHEAR  
OF 30-40 KNOTS, AND FORCING FROM A COLD FRONT WILL SUPPORT SCATTERED  
STRONG-TO-SEVERE STORMS THIS AFTERNOON. MAIN HAZARD BEING DAMAGING  
WIND GUSTS BUT SOME HAIL CAN'T BE COMPLETELY RULED OUT. THE MAIN  
PERIOD OF INTEREST IS 2PM TO MIDNIGHT TODAY. THE FORECAST SOUNDINGS  
STILL SHOW A LONG, SKINNY CAPE PROFILE WITH PWATS OF AROUND 1.6".  
STORM MOTIONS WILL BE QUITE SLOW (20-25 KNOTS) AND PARALLEL TO THE  
FRONT. THE INSTABILITY GRADIENT STILL IS PARALLEL TO THE BULK WIND  
VECTORS. THIS ALL ADDS UP TO BEING A GREAT SET UP FOR FLASH FLOODING  
FROM TRAINING AND SLOW STORM MOTIONS. THE LPMM HAS POCKETS OF 2  
INCHES ACROSS THE AREA.  
 
TEMPERATURES CONTINUE TO HEAT UP THIS WEEK. HIGHS IN THE MID TO  
UPPER 80S LAST INTO SUNDAY. HOWEVER, WE GET BACK INTO THE 90S BY  
MONDAY-WEDNESDAY, LINGERING INTO MIDWEEK. HEAT INDICES POP UP INTO  
THE 100S MONDAY ACROSS ILLINOIS RIVER VALLEY (& NORTH) AND IN THE  
SOUTHEAST. BY WEDNESDAY, THERE IS A 40-60% CHANCE OF HEAT INDICES  
GREATER THAN 100 DEGREES.  
 
COPPLE  
 

 
   
AVIATION
 
(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON)  
ISSUED AT 1247 PM CDT WED JUL 24 2024  
 
SCATTERED SHOWERS AND THUNDERSTORMS WILL AFFECT THE CENTRAL IL  
TERMINALS UNTIL AROUND 00Z AS A COLD FRONT GRADUALLY SAGS  
SOUTHWARD THROUGH THE AREA. A FEW ISOLATED STRONG TO SEVERE STORMS  
WILL BE POSSIBLE, WHILE LATEST OBSERVATIONS FAVOR BRIEF MVFR TO  
IFR CONDITIONS IN THUNDERSTORMS. VFR CONDITIONS EXPECTED TO  
RETURN BY AROUND 00Z, WITH PERHAPS A FEW THUNDERSTORMS LINGERING  
IN THE VICINITY OF THE I-72 TERMINALS KSPI, KDEC, AND KCMI. WINDS  
LIGHT AND VARIABLE NEAR THE FRONT, BECOMING N-NE 5-10 KTS LATE  
THIS AFTERNOON OR EVENING THROUGH THURSDAY MORNING.  
 
37  
 

 
   
ILX WATCHES/WARNINGS/ADVISORIES
 
 
NONE.  

 
 

 
 
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