670  
FXUS63 KILX 271852  
AFDILX  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE LINCOLN IL  
152 PM CDT SUN JUL 27 2025  
   
KEY MESSAGES  
 
- A HEAT ADVISORY IS IN EFFECT FOR ALL OF CENTRAL AND SOUTHEAST  
ILLINOIS MONDAY AFTERNOON AND EARLY EVENING. DANGEROUS HEAT AND  
HUMIDITY WILL LIKELY CONTINUE TUESDAY FOR THE WHOLE AREA, AND  
WEDNESDAY IN SOUTHEAST IL.  
 
- A SIGNIFICANT PATTERN CHANGE WILL ALLOW A STRONG COLD FRONT TO  
PASS THROUGH THE REGION ON WEDNESDAY, BRINGING A RISK OF STRONG  
STORMS AND HEAVY RAIN.  
 
- COOLER AND MUCH LESS HUMID AIR WILL FOLLOW FOR THE END OF THE  
WEEK AND NEXT WEEKEND.  
 
 
   
DISCUSSION  
 
ISSUED AT 152 PM CDT SUN JUL 27 2025  
 
18Z SURFACE MAP INDICATED A WEAK STATIONARY BOUNDARY JUST TO OUR  
NORTH, ORIENTED WNW-ESE NEAR THE I-80 CORRIDOR. THIS HAS BEEN THE  
FOCUS FOR SCATTERED STORMS, WITH LARGELY FAILED ATTEMPTS AT  
CONVECTION SOUTH OF THIS BOUNDARY INTO OUR FAR NORTHERN CWA OVER  
THE PAST 1-2 HOURS. RAP/NAM NON- SUPERCELL TORNADO PARAMETER OF  
1-2 ACROSS THE NORTHERN CWA SHOW THE POSSIBILITY OF FUNNELS  
THROUGH LATE AFTERNOON. OTHERWISE FOR THE REMAINDER OF THE AREA  
RICH LOW- MID LEVEL MOISTURE (75-80F DEW POINTS AND 2" PWATS) AND  
UNCAPPED PROFILES SUPPORT ISOLATED CONVECTION (20% POPS) WITH THE  
HIGHEST COVERAGE SOUTH OF I-70 INTO EARLY THIS EVENING BEFORE  
DIMINISHING. NOT LOOKING FOR A SEVERE THREAT BUT COPIOUS MOISTURE  
WILL LEAD TO HEAVY DOWNPOURS AND FREQUENT LIGHTNING IN THE  
LOCATIONS THAT SEE STORMS. A STRATOCU DECK HAS KEPT TEMPS FROM  
SURGING OVER MUCH OF THE AREA WITH 105+ HEAT INDICES SUPPRESSED  
SOUTH OF I-70 THROUGH 1 PM. HOWEVER, RECENT VISIBLE SATELLITE  
TRENDS SHOW LARGER HOLES OPENING UP, THUS MUCH OF THE AREA IS  
STILL EXPECTED TO SEE 100-105 HEAT INDICES LATE THIS AFTERNOON.  
 
CONVECTIVE ALLOWING MODELS SHOW AN MCS DEVELOPING OVER THE UPPER  
MIDWEST THIS EVENING, DROPPING SOUTHEAST INTO EASTERN IA/NORTHWEST  
IL LATE TONIGHT IN A WEAKENING MODE. SOME MODELS SHOW THIS  
COMPLETELY DECAYING BEFORE REACHING OUR NORTHWEST CWA, WHILE A FEW  
SHOW SOME SHOWERS/STORMS PRIMARILY NORTHWEST OF A CANTON TO  
BLOOMINGTON LINE LATE TONIGHT AND EARLY MONDAY MORNING. KEPT LOW  
CHANCE POPS (20-30%) TO ACCOUNT FOR THIS. REGARDLESS OF PRECIP  
COVERAGE, CONVECTIVE DEBRIS CLOUDS WILL LIKELY SLOW DIURNAL  
WARMING OVER THE NORTHERN HALF OF THE CWA THROUGH MONDAY MORNING.  
HOWEVER, TIME/HEIGHT PROGS SHOW CLEARING LIKELY DURING THE  
AFTERNOON WHICH SHOULD ONCE AGAIN PUSH THE ENTIRE AREA INTO HEAT  
ADVISORY CRITERIA, HEAT INDICES PEAKING NEAR 110F.  
 
SHORT RANGE MODELS SUGGEST A REPEAT PERFORMANCE MON NIGHT/TUE  
MORNING WITH ANOTHER UPPER MIDWEST MCS DROPPING SOUTHEAST IN A  
WEAKENING FASHION. THUS WILL CARRY LOW POPS ACROSS THE NORTH, AND  
AFTER DEBRIS CLOUDS DISSIPATE EXPECTING ANOTHER DANGEROUSLY  
HOT/HUMID AFTERNOON WITH WIDESPREAD HEAT INDICES NEAR 110F.  
 
POTENTIALLY ACTIVE WEATHER WEDNESDAY, AS A NORTHERN STREAM  
SHORTWAVE PUSHES A "REAL" COLD FRONT INTO THE AREA. SHEAR AND  
THERMODYNAMIC PROFILES WOULD SUGGEST A LOW END SEVERE RISK, MAINLY  
DAMAGING WIND GUSTS. CSU-MLP SHOWS A 15% SEVERE RISK FOR ALL OF  
CENTRAL/SE IL. WITH THE HIGH PWAT AIRMASS STILL IN PLACE LOCALLY  
HEAVY RAIN ALSO A RISK. DEPENDING ON FRONTAL TIMING, OUR SOUTHEAST  
COUNTIES MAY BE IN LINE FOR ONE MORE DAY OF HEAT HEADLINES.  
 
MEDIUM RANGE GUIDANCE SHOW A WIDE ENVELOPE IN FRONTAL LOCATION  
THU, SO SOME POPS ARE STILL SHOWN BY THE NBM OVER THE SOUTHERN  
HALF OF THE CWA. BUT THE TREND WILL BE FOR DRYING AND COOLER/LESS  
HUMID CONDITIONS ADVECTING ON NORTHEAST LOW LEVEL FLOW, COURTESY  
OF A LARGE CANADIAN RIDGE BUILDING INTO THE GREAT LAKES. THIS IS  
FORECAST TO CONTINUE INTO NEXT WEEKEND, RESULTING IN NBM FORECAST  
HIGHS IN THE UPPER 70S/LOWER 80S, AND LOWS DIPPING INTO THE 50S  
AND LOWER 60S.  
 
25  
 
 
   
AVIATION  
(FOR THE 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)  
ISSUED AT 1151 AM CDT SUN JUL 27 2025  
 
BKN MVFR CEILINGS AFFECTING KPIA-KBMI-KCMI AT MIDDAY SHOULD RISE  
ABOVE 3K FEET SOON. THIS WILL LEAVE A BKN STRATOCU DECK AT VFR  
LEVELS IN PLACE FOR MOST OF THE AREA THIS AFTERNOON, SCATTERING  
OUT BY EARLY EVENING. WINDS TO BE LIGHT FROM THE SOUTHWEST THROUGH  
THE FORECAST.  
 
25  
 
 
   
ILX WATCHES/WARNINGS/ADVISORIES  
 
HEAT ADVISORY UNTIL 7 PM CDT THIS EVENING FOR ILZ027-029-031-  
036>038-040>057-061>063-066>068-071>073.  
 
HEAT ADVISORY FROM NOON TO 8 PM CDT MONDAY FOR ILZ027>031-  
036>038-040>057-061>063-066>068-071>073.  
 
 
 
 
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