996
FXUS63 KILX 271733
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1233 PM CDT MON JUL 27 2026
KEY MESSAGES
- AREAS OF FOG EARLY THIS MORNING FROM PEORIA TO LINCOLN TO
ROBINSON NORTHEAST WILL BE LOCALLY DENSE ESPECIALLY FROM
BLOOMINGTON TO PARIS NORTHEAST.
- OPPRESSIVE HEAT AND HUMIDITY CONTINUE THROUGH EARLY EVENING
WITH HEAT INDICES PEAKING BETWEEN 105 AND 115 DEGREES AND A
FEW SPOTS HIGHER THIS AFTERNOON.
- MULTIPLE THUNDERSTORM COMPLEXES WILL MOVE ACROSS IL INTO THIS
EVENING, PRESENTING A CONDITIONAL THREAT FOR SEVERE WEATHER.
DAMAGING WINDS AND HEAVY RAINS ARE A RISK ESPECIALLY EARLY
THIS MORNING IN SOUTHEAST IL, AND ACROSS CENTRAL AND SOUTHEAST
IL THIS AFTERNOON AND EARLY EVENING.
- A COLD FRONT WILL BRING RELIEF FROM THE HIGH HEAT AND HUMIDITY ON
TUESDAY, TRANSITIONING US BACK TO NEAR NORMAL TEMPERATURES
AND HUMIDITY LEVELS DURING MID WEEK.
DISCUSSION
ISSUED AT 345 AM CDT MON JUL 27 2026
WE HAVE EXPANDED THE EXTREME HEAT WARNING OVER REST OF CENTRAL
IL EXCEPT HAVING VERMILION, EDGAR AND CLARK COUNTIES IN A HEAT
ADVISORY UNTIL 9 PM TODAY. HEAT INDICES THIS AFTERNOON AND EARLY
EVENING TO PEAK FROM 105-115 WITH A FEW SPOTS GETTING TO 120 OR
HIGHER.
AREAS OF FOG HAVE DEVELOPED PAST FEW HOURS FROM PEORIA TO
LINCOLN AND DECATUR TO ROBINSON NORTHEAST, WITH DENSE FOG
RECENTLY FORMING AT BLOOMINGTON AND DANVILLE. A DENSE FOG
ADVISORY UNTIL 8 AM FROM LIVINGSTON AND LASALLE COUNTIES NORTH.
THE FOG SHOULD LIFT AND PUSH NORTHEAST OF CENTRAL IL BETWEEN 7-8
AM.
MCS OVER WESTERN PARTS OF TN/KY HAS A TAIL OF CONVECTION
EXTENDING NORTHWARD INTO SOUTHEAST IL (EASTERN SHELBY, WESTERN
CUMBERLAND, EFFINGHAM, CLAY AND WESTERN JASPER COUNTIES). FLASH
FLOOD WARNING FOR EASTERN EFFINGHAM COUNTY UNTIL 5 AM AND FOR
SOUTHERN CLAY COUNTY UNTIL 6 AM. A PERSONAL WEATHER STATION ON
NORTH SIDE OF EFFINGHAM MEASURED 3.6 INCHES OF RAIN AT 315 AM
AND WIND GUST 40 MPH. VERY HIGH PWATS WERE 1.9-2.25 INCHES FROM
DECATUR SSE AND CELLS MOVING SSE BUT BACKBUILDING TO THE NORTH
TOWARD DEC AIRPORT. THIS BOUNDARY EXTENDS NORTHWARD INTO DEWITT
AND WESTERN MCLEAN COUNTY SO MAY SEE SOME CELLS DEVELOP HERE TOO
EARLY THIS MORNING. CAMS NOT HANDLING THIS CONVECTION THE BEST
THOUGH ARW IS CLOSER TO REALITY AND ALSO CANADIAN REG LATCHING
ON TO THIS CONVECTION LONGER. SO THIS NARROW BAND OF CONVECTION
MAY LAST A FEW MORE HOURS UNTIL 13Z/8 AM OVER PARTS OF EAST
CENTRAL AND ESPECIALLY SOUTHEAST IL WITH HEAVY RAIN AND FREQUENT
LIGHTNING THE MAIN THREATS. THOUGH A FEW STRONGER CELLS COULD
HAVE WIND GUSTS OVER 40 MPH.
MLCAPES CURRENTLY 2500-4000 J/KG AND MUCAPES ARE 4000-5000 J/KG
OVER CENTRAL/IL WITH A CAP IN PLACE AT DAWN. THIS VERY UNSTABLE
AIR MASS TO LIKELY CONTINUE THROUGH THE AFTERNOON WHEN CAPES
LIKELY TOP 4000 J/KG AND EFFECTIVE BULK SHEAR VALUES OF 30-40
KTS. CHALLENGING FORECAST TODAY WITH CONVECTION CHANCES SINCE
TRIGGERS ARE NOT VERY OBVIOUS. CONSENSUS OF MODELS WAS SHOWING
MCS DEVELOPING OVER WI THIS MORNING AND MOVING SOUTHWARD OVER
CENTRAL IL DURING THIS AFTERNOON/EARLY EVENING. THOUGH THIS
CONVECTION HAS BEEN SLOWER TO DEVELOP IN EAST CENTRAL WI. SPC
DAY1 OUTLOOK HAS UPGRADED TO A SLIGHT RISK OVER CENTRAL AND SW
CWA AND ENHANCED RISK OVER NE CWA THIS AFTERNOON/EARLY EVENING.
THERE IS 15-30% RISK OF DAMAGING WINDS, WITH A LEVEL 1 FOR
WINDS OF OVER 75 MPH OVER MUCH OF CWA. THERE IS A 2% TO LESS
THAN 5% RISK OF TORNADOES OVER CWA. THE ENHANCED RISK IN NE CWA
HAS 5-15% RISK OF LARGE HAIL.
HIGHS TODAY IN THE LOW TO MID 90S COMBINED WITH DEWPOINTS IN THE
UPPER 70S/LOWER 80S TO GIVE AFTERNOON HEAT INDICES OF 110-115
AND FEW PLACES REACHING 120 OR HIGHER. DEWPOINTS GOT INTO THE
MID 80S LATE YESTERDAY AFTERNOON AT SPI AND MACOMB WITH
SPRINGFIELD 84 DEGREES SETTING A NEW RECORD HIGH DEWPOINT.
WE EXPANDED THE EXTREME HEAT WARNING ACROSS REST OF CENTRAL IL
EXCEPT HAVE HEAT ADVISORY FOR VERMILION, EDGAR AND CLARK
COUNTIES UNTIL 9 PM. IF THUNDERSTORMS MATERIALIZE AND MOVE IN
DURING THE AFTERNOON AND EARLY EVENING, IT WOULD COOL TEMPS/HEAT
INDICES AND WOULD LIKELY END THE HEAT HEADLINES EARLIER THAN 9
PM.
MAIN SYNOPTIC COLD FRONT TO PUSH SOUTHWARD ACROSS CENTRAL IL
OVERNIGHT AND COULD PRODUCE ISOLATED CONVECTION WITH BETTER
CHANCES EAST OF IL WHERE BETTER FORCING EXPECTED. MUGGY LOWS
TONIGHT IN THE LOW TO MID 70S, WARMEST IN SOUTHEAST IL. MODEST
NORTHERLY BREEZES ON TUE BRING IN COOLER AND GRADUALLY LESS
HUMID AIR AS DEWPOINTS SLIP INTO THE UPPER 60S/LOWER 70S TUE
AFTERNOON. HIGHS TUE IN THE MID TO UPPER 80S WITH HEAT INDICES
TUE AFTERNOON PEAKING IN THE MID TO UPPER 80S FROM SPRINGFIELD
AND ROBINSON SW. QUIET WEATHER EXPECTED DURING MID WEEK (TUE-
THU) AS WEAK HIGH PRESSURE RIDGE SETTLES INTO IL ON WED WITH
MORE COMFORTABLE TEMPERATURES AND HUMIDITY LEVELS. HIGHS IN THE
LOW TO MID 80S WED AND MID 80S THU WITH LOWS IN THE LOW TO MID
60S TUE AND WED NIGHTS.
MEDIUM RANGE MODELS SHOW A NORTHERN STREAM SHORT WAVE TROF
MOVING INTO IL ON FRIDAY INTO SATURDAY LIKELY BRINGING NEXT
CHANCE OF SHOWERS AND THUNDERSTORMS. HIGHS IN THE LOW TO MID 80S
FRI/SAT AND MID 80S SUNDAY.
THE CLIMATE PREDICTION CENTER (CPC) 8-14 DAY OUTLOOK FOR AUG
3-9TH HAS 50-60% CHANCE OF ABOVE NORMAL TEMPERATURES OVER
CENTRAL AND SOUTHERN IL (45-50% CHANCE ABOVE NORMAL TEMPS IN
NORTHERN IL) WITH PRECIPITATION TRENDING NEAR NORMAL ACROSS IL.
AVIATION /18Z TAFS THROUGH 18Z TUESDAY/
ISSUED AT 1233 PM CDT MON JUL 27 2026
VFR CONDITIONS ARE EXPECTED THROUGH THE 18Z PERIOD. THERE IS A
CHANCE FOR STRONG STORMS LATER THIS AFTERNOON INTO THE EVENING
HOURS. CONFIDENCE IN THE LOCATION AND TIMING OF THE STORMS IS
LOW SO OPTED FOR THE PROB30 GROUP FOR 21-01Z. HEAVY RAIN WILL BE
ACCOMPANYING ANY STORMS, SO LOWERED VISIBILITY IS POSSIBLE IF
THEY MOVE THROUGH. THE WINDS WILL BE VEERING THROUGHOUT THE
PERIOD, BECOMING NORTHERLY BY THE MORNING.
ILX WATCHES/WARNINGS/ADVISORIES
EXTREME HEAT WARNING UNTIL 9 PM CDT THIS EVENING FOR
ILZ027>031-036>038-040>057-061>063-066>068-071>073.
KEY MESSAGES...07
DISCUSSION...07
AVIATION...COPPLE
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