247
FXUS63 KILX 091057
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
557 AM CDT WED SEP 9 2026
KEY MESSAGES
- HEAT INDICES WILL TOP OUT AROUND 100 DEGREES THIS AFTERNOON
SOUTH OF I-72 DUE TO HIGH TEMPERATURES IN THE 90S AND RISING
HUMIDITY LEVELS.
- SCATTERED THUNDERSTORMS THIS MORNING AND AFTERNOON, BECOMING
MORE WIDESPREAD LATE TONIGHT ALONG A STALLED FRONT; LOCALIZED
HEAVY RAINFALL OF 1 TO 3 INCHES COULD CAUSE LOCALIZED
FLOODING, PARTICULARLY SOUTH OF I-70. THERE IS A MARGINAL RISK
(LEVEL 1 OF 5) FOR SEVERE THUNDERSTORMS NEAR/SOUTH OF 1- 72.
DISCUSSION
ISSUED AT 205 AM CDT WED SEP 9 2026
MOISTURE TRANSPORT WILL INCREASE TODAY BRINGING SOUPY DEWPOINTS IN
THE 70S INTO THE CENTRAL PART OF THE STATE. HEAT INDICES WILL BE
GREATEST THE FURTHER SOUTH YOU TRAVEL IN THE STATE, WITH 95+ DEGREE
HEAT INDICES SOUTH OF I-72. HOWEVER, THERE COULD BE SOME LIMITATIONS
WITH THE HOW HIGH THE HEAT INDICES MAY REACH WITH THE CLOUD COVER
FROM CONVECTIVE DEBRIS ACROSS THE STATE AND HOW FAST THE COLD FRONT
TODAY MAY MOVE THROUGH. CURRENTLY, THE FRONT IS LOCATED ACROSS
CENTRAL IOWA, EXTENDING NORTH TO NORTHERN ONTARIO.
THE COLD FRONT WILL CLEAR OUT THE SWELTERING MID TO UPPER 90
TEMPERATURES, LEAVING HIGHS IN THE LOW TO MID 80S BEFORE BUILDING
BACK TO UPPER 80S TO LOW 90S THIS WEEKEND INTO EARLY NEXT WEEK. THE
LREF SUGGESTS THAT THERE IS A 40-70% CHANCE OF HIGH TEMPERATURES
COOLER THAN 80 DEGREES BY NEXT TUESDAY NORTH OF I-72.
SHOWERS AND THUNDERSTORMS WILL MOVE THROUGH TODAY AS THE FRONT
PUSHES SOUTH AND EVENTUALLY STALLS OUT ACROSS THE SOUTHERN HALF OF
THE STATE OVERNIGHT. AT THE MOMENT, THERE IS AN AREA OF CONVECTION
MOVING EAST ACROSS THE NORTHERN HALF OF THE STATE, SCRAPING OUR
NORTHERN MOST COUNTIES EARLY THIS MORNING. THIS INITIAL AREA OF
CONVECTION WILL BEGIN TO PUSH SOUTH AS MORNING PROGRESSES AND WIDELY
DRY OUT LATE THIS MORNING INTO THE AFTERNOON HOURS. SCATTERED
ACTIVITY WILL REMAIN DURING THE AFTERNOON AS THE FRONT PUSHES
SOUTHEAST THROUGH THE STATE. THIS STORMS COULD HAVE STRONG TO
DAMAGING WINDS WITHIN THE STRONGEST STORMS/CLUSTERS.
REDEVELOPMENT MAY BEGIN LATER THAN PREVIOUS FORECASTS, AS THE CAMS
HAVE THE AREA OF NEW CONVECTION MOVING INTO THE SOUTHEAST AROUND 06Z
TONIGHT. THIS CONVECTION LOOKS TO TRAIN NEAR AND SOUTH OF I-72 ALONG
THE STALLED FRONT AS THE LLJ INCREASES. THE HEAVIEST RAIN MAY BE
ALONG AND SOUTH OF THE I-70 CORRIDOR. ANOTHER SCENARIO THAT COULD
OCCUR, IS THAT THIS REDEVELOPMENT DOESN'T HAPPEN OR IS NOT NEARLY AS
WIDESPREAD, AS DEPICTED BY THE RRFS 09.00Z RUN. SAY THE MORE
WIDESPREAD REDEVELOPMENT WITH HEAVY RAIN SCENARIO PLAYS OUT, IT
WOULD CONTINUE INTO THURSDAY MORNING AND POTENTIALLY HAVE A LOW RISK
FOR FLASH FLOODING, RATHER THAN SEVERE THREAT. HOWEVER, THIS AREA
CAN LIKELY TAKE QUITE A BIT OF RAIN BEFORE FLOODING BECOMES A MAJOR
CONCERN. THE 6 HOUR FFG FOR THE SOUTHEAST IS 3-5 INCHES. PWATS IN
THAT AREA ARE FORECAST TO BE 2.0-2.5 INCHES SO VERY HEAVY RAIN IS
POSSIBLE. LOCALIZED SWATHS OF 1 TO 3 INCHES ARE POSSIBLE
(PARTICULARLY ALONG AND SOUTH OF I-70) AS HIGHLIGHTED BY THE HREF
LPMM.
WPC HAS MAINTAINED A D2 MARGINAL RISK ERO ALONG/SOUTH OF I-72. SPC
HAS SHRUNK THE D2 MARGINAL RISK FOR SEVERE WEATHER NEAR/SOUTH OF 1-
72. DAMAGING WINDS ARE THE MOST LIKELY HAZARD WITH THE STRONGEST
STORMS.
ADDITIONAL LOW-END CHANCES EXIST FOR SHOWERS AND THUNDERSTORMS
THROUGH THE WEEKEND. DUE TO LOW PREDICTABILITY AND MODEL SPREAD,
BROAD-BRUSHED 20-40% POPS REMAIN IN PLACE FROM FRIDAY NIGHT THROUGH
EARLY NEXT WEEK.
AVIATION /12Z TAFS THROUGH 12Z THURSDAY/
ISSUED AT 557 AM CDT WED SEP 9 2026
A COLD FRONT WILL BEGIN TO MOVE INTO CENTRAL ILLINOIS THIS
MORNING. BEST CHANCES OF THUNDER WILL BE AT KPIA/KBMI THROUGH
MID MORNING, THOUGH SOUTHERN EXTENT OF THE RAIN IS MORE
QUESTIONABLE AND IT IS UNCERTAIN WHETHER THE RAIN WILL REACH
KDEC/KSPI/KCMI. WINDS DO TURN AROUND TO THE NORTHWEST AT ALL
SITES DURING THE MORNING WITH FRONTAL PASSAGE, THOUGH DROP OFF
IN SPEED TOWARD 00Z, BECOMING LIGHT AND VARIABLE OVERNIGHT.
VFR CONDITIONS EXPECTED WITH CEILINGS GENERALLY AT OR ABOVE
10KFT, THOUGH SOME LOWER CEILINGS CLOSER TO 4000 FEET WILL
ACCOMPANY ANY THUNDERSTORMS. AS WE APPROACH THE END OF THE 12Z
PERIOD, CEILINGS ARE TO DROP TO 3000-4000 FEET. ADDITIONAL RAIN
MAY IMPACT THE SOUTHERN MOST SITES AS WELL BETWEEN 10Z-12Z.
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
KEY MESSAGES...COPPLE
DISCUSSION...COPPLE
AVIATION...COPPLE
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