378
FXUS63 KILX 100517
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1217 AM CDT THU SEP 10 2026
KEY MESSAGES
- LOCALIZED HEAVY RAINFALL TONIGHT WILL YIELD POCKETS OF 1 TO 2
INCH TOTALS NEAR AND SOUTH OF I-70, LEADING TO POTENTIAL
PONDING IN LOW-LYING AREAS.
DISCUSSION
ISSUED AT 1222 PM CDT WED SEP 9 2026
REGIONAL RADAR MOSAIC INDICATES A BAND OF SHOWERS ALONG A
CONFLUENCE ZONE DISSIPATING AS IT TRACKS EAST NEAR I-55 EARLY
THIS AFTERNOON. AN OUTFLOW BOUNDARY WELL AHEAD OF THIS ACTIVITY
WAS TRACKING TOWARD SE IL, AND APPEARS TO BE THE FOCUS FOR
ISOLATED THUNDERSTORM DEVELOPMENT THIS AFTERNOON. THERMODYNAMIC
ANALYSIS INDICATES MLCAPE VALUES BUILDING TO AROUND 1000-1500
J/KG ACROSS SOUTHERN PORTIONS OF THE FORECAST AREA, PRIMARILY
NEAR AND SOUTH OF INTERSTATE 70. WEAK 06 KM BULK SHEAR AROUND
20-25 KNOTS WILL TEND TO LIMIT STORM ORGANIZATION, BUT STEEP
LOW- LEVEL LAPSE RATES DRIVING DCAPE NEAR 1000 J/KG WILL LEAD TO
PULSEY DOWNBURST WINDS IN ANY THUNDERSTORMS THAT MANAGE TO
DEVELOP MID- LATE AFTERNOON. THIS ACTIVITY SHOULD QUICKLY FADE
EARLY EVENING WITH DIMINISHING INSTABILITY.
MOISTURE TRANSPORT RAMPS UP AGAIN OVERNIGHT, AHEAD OF A
SHORTWAVE DIVING SOUTHEAST FROM THE PLAINS. PRECIPITABLE WATER
(PWAT) VALUES WILL CLIMB TO 1.82.0 INCHES ALONG AN ELEVATED
BOUNDARY STRETCHED WEST-EAST OVER CENTRAL IL, WELL ABOVE THE
90TH PERCENTILE FOR EARLY SEPTEMBER. HI-RES MODEL GUIDANCE
DEPICT CLUSTERED CONVECTIVE DEVELOPMENT TRACKING EASTWARD
LATE TONIGHT AND THURSDAY MORNING, MAINLY SOUTH OF THE I-72
CORRIDOR. PROBABILITIES FROM THE HREF REVEAL A 70 PERCENT CHANCE
OF RAINFALL EXCEEDING 1.0 INCH SOUTH OF THE I-70 CORRIDOR, WITH
LOCALIZED MAXIMA UP TO 2.0 INCHES ACROSS SOUTHEAST ILLINOIS BY
THURSDAY MORNING. PAVEMENT PONDING AND LOCALIZED NUISANCE URBAN
FLOODING WILL BE THE PRIMARY IMPACTS.
SHOWERS ARE EXPECTED TO DISSIPATE OVER THE SOUTH HALF OF THE
AREA THURSDAY MORNING. LIGHT WINDS WILL PREVAIL AS THE FRONTAL
ZONE SLOWLY SINKS SOUTH, LEADING TO ANOTHER DAY OF MODERATE
HUMIDITY LEVELS, ESPECIALLY SOUTH OF I-72. DRY AND MILD WEATHER
WILL DOMINATE FRIDAY AS HIGH PRESSURE BUILDS THROUGH THE
EASTERN GREAT LAKES.
ENSEMBLE GUIDANCE GENERALLY AGREES ON THE NEXT FRONT REACHING
CENTRAL IL THIS WEEKEND. UPPER LEVEL SUPPORT DOESN'T LOOK GREAT
AND WE APPEAR TO BE NEAR THE TAIL END OF THE FRONT, SO WE
MAINTAIN LOW CHANCE POPS FOR SATURDAY AND SATURDAY NIGHT.
TEMPERATURES WILL AVERAGE A BIT ABOVE NORMAL SAT-SUN WITH HIGHS
IN THE MID- UPPER 80S. A BUILDING UPPER-LEVEL RIDGE ACROSS THE
CENTRAL CONUS EARLY NEXT WEEK WILL FOSTER A FURTHER WARMING
TREND FOR MONDAY AND TUESDAY, PUSHING HIGH TEMPERATURES INTO THE
LOWER 90S. FURTHERMORE, THE CLIMATE PREDICTION CENTER (CPC)
6-10 DAY OUTLOOK INDICATES A 40 TO 70 PERCENT PROBABILITY OF
ABOVE-NORMAL TEMPERATURES ACROSS CENTRAL ILLINOIS THROUGH
SEPTEMBER 18TH.
AVIATION /06Z TAFS THROUGH 06Z FRIDAY/
ISSUED AT 1217 AM CDT THU SEP 10 2026
GRADUAL DETERIORATION OF CEILINGS IS EXPECTED LATER TONIGHT,
INITIALLY FOCUSED ON AN AREA OF CLEARING THAT WILL TAKE PLACE
NORTHWEST OF KPIA. THIS AREA HAD DECENT RAINFALL ON THURSDAY,
AND AN EXPANSION OF STRATUS/FOG SHOULD RESULT AS SKIES INITIALLY
CLEAR. BY 12Z, MOST OF CENTRAL ILLINOIS SHOULD SEE CEILINGS IN
THE 1-2KFT RANGE. NBM PROBABILITIES OF IFR CEILINGS ARE HIGHEST
IN A NARROW WEST-EAST AXIS ACROSS KPIA/KBMI (50-70%), DIMINISHING
TO AROUND 40% FURTHER SOUTH FROM THERE. KPIA/KBMI MAY BE BACK
TO VFR CEILINGS AS EARLY AS 14-15Z, THOUGH IT MAY TAKE UNTIL
LATE AFTERNOON FOR THE MORE SOUTHERN TERMINALS TO SEE DECENT
IMPROVEMENT.
IN ADDITION, THE KSPI-KCMI CORRIDOR WILL BE MORE FAVORED FOR
RAIN SHOWERS AND PERIODS OF THUNDERSTORMS THROUGH THE MORNING,
WITH PROB30 MENTIONS FOR TSRA AT THESE SITES TIMED OVER THE MOST
FAVORED 3-HOUR PERIODS.
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
KEY MESSAGES...25
DISCUSSION...25
AVIATION...GEELHART
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