845
FXUS63 KILX 151906
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
206 PM CDT TUE SEP 15 2026
KEY MESSAGES
- A LEVEL 1 RISK OF SEVERE WEATHER CONTINUES THROUGH THIS
EVENING, WITH POTENTIAL FOR LOCALIZED DAMAGING WINDS.
- THE STORMS TONIGHT WILL PRODUCE AREAS OF HEAVY RAIN, WITH
POTENTIAL FOR LOCALIZED FLOODING NORTH OF I-72 WHERE TRAINING
STORMS ARE MORE LIKELY.
- THE UNSEASONABLY HOT WEATHER WILL CONTINUE IN AREAS SOUTH OF
I-72 INTO THE WEEKEND.
DISCUSSION
ISSUED AT 206 PM CDT TUE SEP 15 2026
PRIMARY BOUNDARY STRETCHES FROM JUST NORTH OF QUINCY TO NEAR LA
SALLE THIS HOUR, WHILE SATELLITE CONTINUES TO SHOW AN AREA OF
ACCAS JUST SOUTH OF IT. TEMPERATURES SOUTH OF THE BOUNDARY ARE
WIDELY IN THE MID 90S, WITH A FEW MESONET SITES SOUTH OF I-72
EVEN WARMER. THE CAP HAS ERODED AND MESOANALYSIS INDICATES ABOUT
2500 J/KG OF SBCAPE NEAR THIS BOUNDARY, ALONG WITH ABOUT 30
KNOTS OF 0-6KM SHEAR. SO FAR THE CONVECTION HAS REMAINED FAIRLY
SCATTERED AND MOSTLY THUNDER FREE, THOUGH AN UPTICK IN
CONVECTION IS EXPECTED TOWARD MID AFTERNOON WHERE CUMULUS CLOUDS
HAVE RECENTLY BEEN BLOSSOMING. A COUPLE MAIN PERIODS OF STORMS
ARE EXPECTED, ONE THROUGH ABOUT SUNSET, THEN AN UPTICK IN
DEVELOPMENT FROM THE WEST MID TO LATE EVENING AND PAST MIDNIGHT.
BESIDES THE THREAT OF SOME ISOLATED DAMAGING WIND GUSTS, HIGH
PRECIPITABLE WATER VALUES OVER 2 INCHES (NEAR THE TOP OF
CLIMATOLOGY FOR MID SEPTEMBER) WILL PRODUCE AREAS OF HEAVY RAIN.
LPMM GUIDANCE FROM THE HREF SUGGESTS POTENTIAL FOR 2-3 INCHES IN
SWATHS OF HEAVY RAIN, ESPECIALLY THIS EVENING WHEN MORE IN THE
WAY OF CELL TRAINING IS EXPECTED. FLASH FLOOD GUIDANCE IS 2-2.5
INCHES IN AN HOUR ACROSS MUCH OF CENTRAL ILLINOIS, SO THERE
COULD BE SOME LOCALIZED FLOODING IF THE RAIN COMES DOWN TOO
FAST.
BY WEDNESDAY MORNING, THE FRONT IS EXPECTED TO BE SOMEWHERE
BETWEEN I-72 AND I-70, WHERE IT SHOULD LOITER FOR A DAY OR SO AS
IT BECOMES PARALLEL TO THE UPPER FLOW. RAIN CHANCES WILL
CONTINUE INTO THURSDAY NORTH OF THE BOUNDARY, WITH THE HEAVY
RAIN THREAT GRADUALLY SHIFTING INTO NORTHERN ILLINOIS. BY LATE
WEEK, THE FRONT SHOULD BE BACK NORTH OF THE AREA, BEFORE A
SHORTWAVE ARRIVES TO START THE WEEKEND. THE BOUNDARY IS EXPECTED
TO STALL ONCE AGAIN OVER CENTRAL ILLINOIS. AS AN UPPER LOW
CLOSES OFF OVER THE NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY
EARLY NEXT WEEK, ANY PUSH OF THIS FRONT OUT OF THE AREA WILL BE
SLOW. THUS, RAIN CHANCES WILL LINGER OVER PORTIONS OF CENTRAL
ILLINOIS, THOUGH THEY WILL BE HIGHEST SATURDAY NIGHT INTO SUNDAY
EVENING.
TEMPERATURE-WISE, A SIGNIFICANT RANGE IN HIGHS IS EXPECTED OVER
THE FORECAST AREA THROUGH THE WEEKEND. HIGHS IN THE 90S WILL
CONTINUE SOUTH OF THE BOUNDARY. NORTH OF THERE, 80S WILL BE MORE
COMMON, THOUGH WITH LOWER CLOUDS AND RAIN ON WEDNESDAY, AREAS
NORTH OF HAVANA AND BLOOMINGTON ARE LIKELY TO REMAIN IN THE 70S.
AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/
ISSUED AT 1223 PM CDT TUE SEP 15 2026
SCATTERED SHOWERS/STORMS WILL INCREASE THIS AFTERNOON ALONG A
BOUNDARY, PRIMARILY IMPACTING KPIA/KBMI THROUGH 00Z. STORMS
FURTHER SOUTH WILL BE MORE WIDELY SCATTERED, AND WILL ONLY
MENTION A PROB30 FOR THE KSPI-KCMI AREA VS. THE TEMPO FURTHER
NORTH. A MORE WIDESPREAD AREA OF SHOWERS AND THUNDERSTORMS
WILL MOVE IN MID TO LATE EVENING AND PERSIST MUCH OF THE NIGHT.
ACCOMPANYING THIS LATTER AREA OF RAIN WILL BE DETERIORATING
CEILINGS, WITH 50-80% CHANCES OF IFR CONDITIONS FROM KSPI-KBMI
BEFORE 12Z. SLOW IMPROVEMENT IN THE CEILINGS IS EXPECTED FROM
SOUTH TO NORTH WEDNESDAY MORNING, THOUGH CHANCES OF CEILINGS
BELOW 3000 FEET REMAIN HIGH (70-90%) AT KPIA/KBMI THROUGH
MIDDAY.
SOUTHWEST WINDS WILL BECOME NORTHERLY TOWARD 00Z AT KBMI/KPIA BY
00Z AS A FRONT SETTLES INTO THE AREA. THE BOUNDARY SHOULD BE
SOUTH OF KSPI-KCMI BY 06Z.
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
KEY MESSAGES...GEELHART
DISCUSSION...GEELHART
AVIATION...GEELHART
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