704  
FXUS63 KILX 260605  
AFDILX  
 
AREA FORECAST DISCUSSION...UPDATED AVIATION  
NATIONAL WEATHER SERVICE LINCOLN IL  
105 AM CDT SAT JUL 26 2025  
   
KEY MESSAGES
 
 
- A LOW PROBABILITY (5-15% CHANCE) OF SEVERE WEATHER EXISTS NORTH  
OF THE I-70 CORRIDOR BOTH TODAY AND SATURDAY.  
 
- A HEAT ADVISORY IS IN EFFECT ALONG AND SOUTH OF A QUINCY TO  
PARIS LINE THROUGH SATURDAY. THE OPPRESSIVE HEAT WILL SPREAD  
BACK NORTHWARD ACROSS ALL OF CENTRAL ILLINOIS SUNDAY THROUGH  
TUESDAY AS HEAT INDEX VALUES ONCE AGAIN REACH 105-115.  
 
- MUCH COOLER WEATHER IS ON TAP FOR THE MIDDLE AND END OF NEXT  
WEEK...WITH A HIGH PROBABILITY (50-70% CHANCE) THAT HIGHS DROP  
BELOW 80 DEGREES BY NEXT THURSDAY.  
 

 
   
UPDATE
 
 
ISSUED AT 839 PM CDT FRI JUL 25 2025  
 
A FEW CLUSTERS OF THUNDERSTORMS CONTINUE ACROSS CENTRAL ILLINOIS  
THIS EVENING, THOUGH HAVE SEEN A DOWN-TICK IN THE OVERALL  
INTENSITY OVER THE PAST HOUR OR SO. EXPECT THE SEVERE THREAT TO BE  
LOW OVERNIGHT AS THE BOUNDARY LAYER CONTINUES TO STABILIZE WITH  
LOSS OF DAYTIME HEATING AND INCREASING MLCIN. THAT BEING SAID,  
STORMS STRETCH BACK ACROSS PORTIONS OF MISSOURI AND KANSAS WITH  
SEVERAL MODELS SUGGESTING THAT CONVECTION MAY FILL BACK IN AS THE  
LOW LEVEL JET STRENGTHENS TO OUR WEST LATE THIS EVENING. AS STORMS  
TRACK NORTHEAST INTO CENTRAL ILLINOIS OVERNIGHT, SLOW STORM  
MOTIONS AND SOME POSSIBLE TRAINING MAY RESULT IN SOME VERY  
LOCALIZED HEAVY RAIN AND POTENTIAL FLOODING, ESPECIALLY NEAR THE  
ILLINOIS RIVER VALLEY WHICH EXPERIENCED SOME HEAVY RAIN EARLIER.  
 
DEUBELBEISS  
 

 
   
DISCUSSION
 
 
ISSUED AT 217 PM CDT FRI JUL 25 2025  
 
A SLOW-MOVING FRONTAL BOUNDARY STRETCHES FROM TOPEKA, KANSAS, TO  
CHICAGO, ILLINOIS. SOUTH OF I-70, A REMNANT OUTFLOW FROM THIS  
MORNINGS CONVECTION IS VISIBLE ON SATELLITE AND RADAR. BOTH  
BOUNDARIES WILL BE THE FOCUS FOR SCATTERED THUNDERSTORMS THIS  
AFTERNOON.  
 
A SEASONABLY HOT AND HUMID AIRMASS IS PRESENT, WITH TEMPERATURES  
IN THE MID-TO-UPPER 80S AND DEWPOINTS IN THE MID-70S. THE RAP  
ANALYZES MODERATELY BUOYANT BOUNDARY LAYER CONDITIONS (1500-2500  
J/KG MLCAPE) ACROSS CENTRAL AND SOUTHEAST IL. MODEST DEEP-LAYER  
SHEAR (< 25 KTS) WILL LIMIT SEVERE WEATHER COVERAGE. HOWEVER,  
STEEP LOW-LEVEL LAPSE RATES (> 8 C/KM) AMID MODERATE BUOYANCY  
COULD SUPPORT MULTI-CELL CLUSTERS CAPABLE OF DAMAGING DOWNBURST  
WINDS THROUGH EARLY EVENING.  
 
TONIGHT, BETTER COVERAGE OF SHOWERS AND THUNDERSTORMS WILL EVOLVE  
FURTHER NORTH NEAR THE FRONTAL BOUNDARY AS A MODEST (20-25 KT)  
LOW-LEVEL JET IMPINGES FROM THE SOUTH. HIGH-RESOLUTION GUIDANCE  
HIGHLIGHTS A CORRIDOR OF CONVECTION DEVELOPING NEAR THE FRONTAL  
BOUNDARY FROM KANSAS CITY TO CHICAGO. HIGH MOISTURE CONTENT (PW >  
2") AND SLOW STORM MOTIONS BRING A POSSIBILITY OF LOCALIZED FLASH  
FLOODING. THE 12Z HREF QPF 6-HR PMM SHOWS POCKETS OF 1.5"-2"  
OVERNIGHT, MAINLY NORTH OF THE IL RIVER VALLEY, WHERE THE 6-HR  
FLASH FLOOD GUIDANCE MAY BE EXCEEDED. A FLOOD WATCH HAS BEEN  
ISSUED FOR KNOX, STARK, AND MARSHALL COUNTIES DUE TO THE HIGH  
PROBABILITY OF HEAVY RAINFALL.  
 
ADDITIONAL THUNDERSTORM ACTIVITY IS ANTICIPATED LATE SATURDAY  
MORNING AND THROUGH THE AFTERNOON AS A CONVECTIVELY-INDUCED  
SHORTWAVE/MCV MOVES ACROSS CENTRAL AND NORTHERN IL. ROBUST PWATS  
AND A LINGERING LOW-LEVEL JET WILL AGAIN FAVOR LOCALIZED POCKETS  
OF +1"/HR RAINFALL RATES. A LOW SEVERE-WEATHER RISK ALSO EXISTS  
SOUTH OF THE FRONTAL BOUNDARY AND NEAR ANY RESIDUAL OUTFLOWS.  
 
THE CONTINUED HOT AND HUMID CONDITIONS HAVE PROMPTED AN EXTENSION  
AND EXPANSION OF THE HEAT ADVISORY THROUGH SATURDAY AFTERNOON.  
HEAT INDEX VALUES OF 100-105 F WILL BE COMMON NEAR AND ESPECIALLY  
SOUTH OF THE I-72/DANVILLE CORRIDOR. THIS ADVISORY WILL LIKELY BE  
EXTENDED INTO SUNDAY, WITH A POSSIBLE EXTREME HEAT WATCH FOR  
MONDAY AND TUESDAY ACROSS PARTS OF CENTRAL AND SOUTHEAST IL. BY  
THEN, THE FRONTAL BOUNDARY WILL HAVE SHIFTED NORTH, MITIGATING  
RAIN/CONVECTIVE POTENTIAL AND ASSOCIATED TEMPERATURE BUSTS. DAILY  
HEAT INDEX VALUES MONDAY AND TUESDAY ARE FORECAST TO SPIKE NEAR  
110 F.  
 
A MAJOR PATTERN CHANGE WILL OCCUR BY THE MIDDLE OF NEXT WEEK AS  
THE HEAT DOME BREAKS DOWN AND AN EXPANSIVE AREA OF CANADIAN HIGH  
PRESSURE SINKS INTO THE UPPER MIDWEST AND GREAT LAKES. DAILY HIGHS  
THURSDAY AND FRIDAY MAY NOT EXCEED 80 DEGREES.  
 
MJA  
 

 
   
AVIATION
 
(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)  
ISSUED AT 105 AM CDT SAT JUL 26 2025  
 
CLUSTERS OF CONVECTION CONTINUE TO LIFT NORTHEASTWARD ACROSS  
CENTRAL ILLINOIS EARLY THIS MORNING...MAINLY ALONG AND JUST NORTH  
OF THE I-72 CORRIDOR. BASED ON CURRENT RADAR TRENDS, HAVE  
MAINTAINED THUNDER AT KSPI/KDEC THROUGH 07Z, AT KCMI THROUGH 08Z,  
AND AT KBMI THROUGH 09Z. ONCE THIS ACTIVITY EXITS, ATTENTION WILL  
TURN TO ADDITIONAL CONVECTION FORMING UPSTREAM N/NE OF KANSAS  
CITY. THESE STORMS WILL GRADUALLY SPREAD NE OVERNIGHT AND WILL  
LIKELY IMPACT NORTH-CENTRAL ILLINOIS AFTER 10Z. HAVE THEREFORE  
ADDED A PROB30 FOR THUNDER AT KPIA/KBMI BETWEEN 10Z AND 14Z. AFTER  
THE EARLY MORNING SHOWERS DIMINISH, SCATTERED STORMS WILL  
REDEVELOP ALONG OLD OUTFLOW BOUNDARIES DURING PEAK HEATING.  
PINPOINTING THIS ACTIVITY IS CHALLENGING AT THIS TIME RANGE, BUT  
HAVE GENERALLY MAINTAINED PROB30 FOR THUNDER AT ALL TERMINALS FOR  
THE AFTERNOON.  
 
BARNES  
 

 
   
ILX WATCHES/WARNINGS/ADVISORIES
 
 
FLOOD WATCH THROUGH THIS EVENING FOR ILZ027-028-030.  
 
HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR ILZ049>057-061>063-  
066>068-071>073.  
 

 
 

 
 
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