648  
FXUS63 KILX 271033  
AFDILX  
 
AREA FORECAST DISCUSSION...UPDATED AVIATION  
NATIONAL WEATHER SERVICE LINCOLN IL  
533 AM CDT SUN JUL 27 2025  
   
KEY MESSAGES  
 
- A HEAT ADVISORY IS IN EFFECT FOR ALL OF CENTRAL AND SOUTHEAST  
ILLINOIS TODAY AS AFTERNOON HEAT INDEX READINGS CLIMB INTO THE  
100 TO 105 DEGREE RANGE. EVEN HOTTER CONDITIONS ARE EXPECTED FOR  
MONDAY AND TUESDAY.  
 
- A SIGNIFICANT PATTERN CHANGE WILL ALLOW A STRONG COLD FRONT TO  
PASS THROUGH THE REGION ON WEDNESDAY...FOLLOWED BY MUCH COOLER  
TEMPERATURES IN THE UPPER 70S AND LOWER 80S THURSDAY THROUGH  
SATURDAY.  
 
 
   
SHORT TERM  
(TODAY THROUGH MONDAY)  
ISSUED AT 328 AM CDT SUN JUL 27 2025  
 
A WEAK 20-25KT 850MB LOW-LEVEL JET ORIENTED FROM KANSAS/OKLAHOMA  
NORTHEASTWARD INTO ILLINOIS IS INTERACTING WITH AN OUTFLOW BOUNDARY  
TO PRODUCE PERSISTENT CLUSTERS OF THUNDERSTORMS ALONG A BOWLING  
GREEN, MISSOURI TO LITCHFIELD, ILLINOIS LINE EARLY THIS MORNING.  
MRMS RADAR ESTIMATES RANGE FROM 2-4 INCHES ACROSS THIS AREA...WITH  
ISOLATED POCKETS IN EXCESS OF 7 INCHES. MEANWHILE FURTHER NORTH OF  
THE MAIN CONVECTION, SCATTERED SHOWERS/THUNDERSTORMS HAVE  
DEVELOPED IN THE ILLINOIS RIVER VALLEY SOUTH OF PEORIA AND ARE  
TRACKING EASTWARD TOWARD THE I-55 CORRIDOR. THESE CELLS ARE  
CONSIDERABLY WEAKER AND LESS ORGANIZED THAN THOSE TO THE SOUTH AND  
THEREFORE DO NOT POSE A WIDESPREAD FLOODING RISK. AS A RESULT,  
HAVE OPTED TO CANCEL THE FLOOD WATCH. THE ACTIVITY MAY SPREAD AS  
FAR EAST AS I-57 BY DAYBREAK: HOWEVER, AREAL COVERAGE WILL TEND TO  
DECREASE AS THE NOCTURNAL JET WEAKENS BY MID-MORNING. AFTER THAT,  
SCATTERED SHOWERS/STORMS WILL RE-DEVELOP BY PEAK HEATING...ESPECIALLY  
ALONG/SOUTH OF I-70 IN CLOSER PROXIMITY TO A LINGERING OUTFLOW  
BOUNDARY. WHILE SBCAPES WILL EXCEED 3000J/KG THIS AFTERNOON, 0-6KM  
SHEAR WILL BE LESS THAN 20KT...LEADING TO LITTLE OR NO STORM  
ORGANIZATION. THEREFORE THE SEVERE WEATHER RISK IS MINIMAL...WITH  
A FEW CELLS PRODUCING LOCALLY HEAVY DOWNPOURS AND GUSTY WINDS.  
THE MAIN WEATHER STORY TODAY WILL BE THE HEAT AND HUMIDITY. HIGH  
TEMPERATURES WILL REACH THE UPPER 80S TO AROUND 90 DEGREES WHILE  
HEAT INDEX VALUES PEAK AT 100-105 DEGREES. A HEAT ADVISORY  
THEREFORE REMAINS IN EFFECT FOR ALL OF CENTRAL AND SOUTHEAST  
ILLINOIS.  
 
THE HEAT ADVISORY WILL MOST LIKELY NEED TO BE CONTINUED INTO  
MONDAY. WILL HOWEVER NEED TO KEEP AN EYE ON POTENTIAL CONVECTION  
DEVELOPING ACROSS THE NORTHERN PLAINS TONIGHT, AS IT TRACKS  
SOUTHEASTWARD TOWARD THE REGION MONDAY MORNING. WHILE MODEL  
SOLUTIONS VARY, A FEW CAMS SUCH AS THE HRRR/WRF-ARW/FV3 SUGGEST A  
DECAYING LINE OF STORMS COULD POTENTIALLY DROP AS FAR SOUTH AS THE  
I-72 CORRIDOR BEFORE DISSIPATING. IF THIS SCENARIO PLAYS OUT,  
TEMPS ACROSS THE NORTHERN KILX CWA MAY NOT BE QUITE AS HOT AS  
CURRENTLY ADVERTISED.  
 
BARNES  
   
LONG TERM  
(TUESDAY THROUGH SATURDAY)  
ISSUED AT 328 AM CDT SUN JUL 27 2025  
 
THE HOTTEST DAY OF THE FORECAST PERIOD WILL BE TUESDAY WHEN HIGHS  
REACH THE LOWER TO MIDDLE 90S AND CORRESPONDING HEAT INDEX VALUES  
PEAK AT 105-115 DEGREES.  
 
AS HAS BEEN NOTED BY THE PAST SEVERAL MODEL RUNS, A PATTERN  
CHANGE WILL TAKE PLACE LATER THIS WEEK AS ENERGY ROTATING AROUND  
A DEEP UPPER LOW OVER HUDSON BAY SUPPRESSES THE PREVAILING RIDGE  
OVER THE MIDWEST/OHIO RIVER VALLEY. THIS WILL SEND A STRONG COLD  
FRONT THROUGH CENTRAL ILLINOIS ON WEDNESDAY...FOLLOWED BY MUCH  
COOLER AND LESS HUMID CONDITIONS BY THE END OF THE WEEK. THE 00Z  
NBM EVEN SUGGESTS A HIGH PROBABILITY (70-90% CHANCE) THAT HIGH  
TEMPERATURES DROP BELOW 80 DEGREES EVERYWHERE NORTH OF THE I-70  
CORRIDOR BY NEXT FRIDAY AND SATURDAY.  
 
BARNES  
 
 
   
AVIATION  
(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING)  
ISSUED AT 532 AM CDT SUN JUL 27 2025  
 
BLOWOFF FROM CONVECTION NEAR AND NORTH OF THE SAINT LOUIS METRO IS  
CREATING A MID/HIGH OVERCAST ACROSS CENTRAL ILLINOIS EARLY THIS  
MORNING. SCATTERED SHOWERS/THUNDER CONTINUE TO PERCOLATE NORTH OF  
THE MAIN AREA OF CONVECTION NEAR QUINCY...AND THIS ACTIVITY IS  
DRIFTING EASTWARD. WHILE RECENT TRENDS HAVE SHOWN WEAKENING, THINK  
IT IS STILL PRUDENT TO CARRY A PROB30 GROUP FOR THUNDER AT KSPI  
THROUGH 13Z. THE EARLY MORNING SHOWERS WILL GRADUALLY DISSIPATE,  
FOLLOWED BY WIDELY SCATTERED RE-DEVELOPMENT BY PEAK HEATING. MOST  
CAMS ARE SPARSE WITH THEIR AREAL COVERAGE, SO HAVE OPTED NOT TO  
MENTION THUNDER AT ANY OF THE TERMINALS THIS AFTERNOON. ANY LATE  
DAY SHOWERS WILL FADE AWAY TOWARD SUNSET, FOLLOWED BY DRY WEATHER  
ACROSS THE BOARD TONIGHT. WINDS WILL INITIALLY BE W/SW AT LESS  
THAN 10KT, THEN WILL BACK TO S AND REMAIN LIGHT TONIGHT.  
 
BARNES  
 
 
   
ILX WATCHES/WARNINGS/ADVISORIES  
 
HEAT ADVISORY FROM 11 AM THIS MORNING TO 7 PM CDT THIS EVENING  
FOR ILZ027-029-031-036>038-040>043-047-048.  
 
HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR ILZ044>046-049>057-  
061>063-066>068-071>073.  
 
 
 
 
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