590
FXUS63 KILX 302313
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
613 PM CDT WED SEP 30 2026
KEY MESSAGES
- WIDESPREAD HEAVY PRECIPITATION IS EXPECTED LATE THURSDAY
MORNING THROUGH FRIDAY. NARROW BANDS OF RAIN COULD PRODUCE
LOCALIZED TOTALS EXCEEDING 2 INCHES.
- DRIER, FALL-LIKE WEATHER BEGINS FRIDAY NIGHT AND CONTINUES
THROUGH EARLY NEXT WEEK.
DISCUSSION
ISSUED AT 111 PM CDT WED SEP 30 2026
18Z SURFACE ANALYSIS SHOWS HIGH PRESSURE CENTERED OVER THE EAST
COAST OF THE US WITH LOW PRESSURE OVER THE OKLAHOMA PANHANDLE. A
RIBBON OF BOTH PACIFIC AND GULF MOISTURE EXTENDS NORTH FROM THE LOW
INTO PARTS OF OF THE MIDDLE MISSISSIPPI VALLEY AND GREAT LAKES
REGION. THIS IS COLLOCATED WITH A 30-40 KT LLJ AND HAS RESULTED
IN A LARGE AREA OF WARM-AIR ADVECTION STEADY RAIN SHOWERS OVER
A GOOD PORTION OF THE CENTRAL US, INCLUDING NORTH-CENTRAL
ILLINOIS. RADAR ESTIMATES SHOW THE HIGHEST PRECIPITATION AMOUNTS
HAVE FALLEN NORTH OF THE ILLINOIS RIVER VALLEY, WHERE IS
PAINTING APPROXIMATELY 0.5-1.5". A LULL IN THE PRECIPITATION IS
ANTICIPATED THIS EVENING AND OVERNIGHT AS MID-LEVEL HEIGHTS
RISE WITH A SMALL AREA OF RIDGING. LINGERING CLOUD COVER WILL
KEEP OVERNIGHT TEMPERATURES MILD WITH FORECAST LOWS EXPECTED TO
BE IN THE UPPER 60S TO LOW 70S.
A CLOSED UPPER LOW OVER THE SOUTH-CENTRAL PLAINS WILL BECOME AN OPEN
WAVE ON THURSDAY AS UPPER RIDGING BUILDS OVER THE SOUTHWEST US. AT
THE SURFACE, A COLD FRONT WILL APPROACH FROM THE NORTHWEST, SPILLING
THE TROPICAL MOISTURE FURTHER SOUTHEAST THROUGH THE AREA AND
BRINGING ANOTHER ROUND OF SHOWERS AND STORMS THURSDAY INTO FRIDAY,
THIS TIME MORE WIDESPREAD. CLIMATOLOGICALLY HIGH PWATS AND DEEP WARM-
CLOUD LAYERS WILL BRING POCKETS OF MODERATE TO HEAVY RAINFALL. THE
30.12Z HREF 24 HOUR QPF LOCALIZED PROBABILITY-MATCHED MEAN (LPMM)
ENDING AT 12Z FRIDAY SHOWS SEVERAL NARROW BANDS OF 2 TO 3"+ OF RAIN
ACROSS CENTRAL ILLINOIS. ALTHOUGH WE CAN TAKE SOME RAIN, LOCALIZED
FLOODING COULD BECOME AN ISSUE ESPECIALLY IF THE RAIN FALLS OVER
AREAS THAT RECEIVED THE HEAVIER RAINFALL AMOUNTS TODAY.
PRECIPITATION WILL COME TO AN END BY FRIDAY AFTERNOON AS THE FRONT
QUICKLY PUSHES SOUTH OF HERE.
HIGH PRESSURE SETTLES INTO THE MIDWEST STATES BEHIND THE COLD FRONT
LATE FRIDAY INTO SATURDAY, BRINGING A PERIOD OF COOLER AND DRIER
WEATHER THROUGH EARLY NEXT WEEK. HIGH TEMPERATURES LOOK TO TOP
OUT IN THE UPPER 60S TO LOW 70S WITH OVERNIGHT LOWS IN THE 40S.
AVIATION /00Z TAFS THROUGH 00Z FRIDAY/
ISSUED AT 613 PM CDT WED SEP 30 2026
SOUTHERLY WINDS EXPECTED TO BECOME MORE PREDOMINANT NEAR 10
KNOTS ACROSS MOST OF THE TERMINALS BY 06Z, THOUGH A FRONTAL
BOUNDARY NEAR KPIA MAY NOT QUITE MAKE IT THAT FAR NORTH BEFORE
DAYBREAK. CEILINGS THROUGH 12Z EXPECTED TO AVERAGE AROUND 10KFT
OR SO, THOUGH A SLOW LOWERING FROM THE NORTHWEST WILL BEGIN
THURSDAY MORNING. HREF PROBABILITIES OF MVFR CEILINGS REACH
ABOUT 60-70% AT KPIA AROUND 18-19Z, AND KBMI-KSPI TOWARD THE END
OF THE FORECAST PERIOD, AS RAIN SHOWERS START TO BECOME
WIDESPREAD. IMPACTS FURTHER SOUTHEAST ARE MORE LIKELY THURSDAY
EVENING.
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
KEY MESSAGES...NMA
DISCUSSION...NMA
AVIATION...GEELHART
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