555
FXUS63 KILX 182323
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
623 PM CDT MON MAY 18 2026
KEY MESSAGES
- REPEATING ROUNDS OF SHOWERS AND STORMS COULD CAUSE FLASH
FLOODING SOUTH OF A SHELBYVILLE TO PARIS LINE THROUGH THIS
EVENING. A FLOOD WATCH IS IN EFFECT FOR THESE AREAS.
- ADDITIONAL THUNDERSTORMS WILL DEVELOP ALONG AN ADVANCING COLD
FRONT ON TUESDAY, WITH A SLIGHT RISK (LEVEL 2 OF 5) FOR SEVERE
STORMS EAST OF INTERSTATE 55. DAMAGING WINDS, LARGE HAIL, AND
HEAVY RAINFALL WOULD BE THE MOST LIKELY HAZARDS.
DISCUSSION
ISSUED AT 223 PM CDT MON MAY 18 2026
A LINE OF SHOWERS AND THUNDERSTORMS HAS STALLED OUT SOUTH OF THE I-
72 CORRIDOR THIS AFTERNOON. ALTHOUGH WIND SHEAR HAS INCREASED OVER
THIS AREA SINCE THIS MORNING, INSTABILITY HAS SIGNIFICANTLY WANED
AND HAS PREVENTED STORMS FROM LARGELY BECOMING ORGANIZED. DESPITE
THIS, CANNOT COMPLETELY RULE OUT A STRONG UPDRAFT OR TWO OVER THE
NEXT FEW HOURS IN FAR SOUTHEAST ILLINOIS WHERE RAP MESOANALYSIS
SHOWS SBCAPE OF 1000+ J/KG. IF ANY STRONG STORMS DO OCCUR, DAMAGING
WINDS WOULD BE POSSIBLE. THE MAIN THREAT THROUGH THE EVENING WILL BE
HEAVY RAINFALL WITH PWATS UP AROUND 1.5 TO 2 INCHES AND HOURLY
RAINFALL RATES UP AROUND 1 INCH IN THE HEAVIEST OF STORMS. A FLOOD
WATCH HAS BEEN ISSUED FOR AREAS SOUTH OF A SHELBYVILLE TO PARIS LINE
THROUGH THIS EVENING.
FURTHER WEST, ADDITIONAL THUNDERSTORMS HAVE DEVELOPED OVER THE
CENTRAL PLAINS AHEAD OF A COLD FRONT AND WILL TRACK EAST THROUGH
TONIGHT, APPROACHING WESTERN ILLINOIS SOMETIME AFTER MIDNIGHT. THESE
STORMS SHOULD WEAKEN AS THEY ENTER THE AREA DUE TO LACK OF
INSTABILITY, THOUGH THEY COULD STILL PRODUCE GUSTY SUBSEVERE WINDS
AS THEY TRACK THROUGH THE WESTERN HALF OF THE STATE. MOST OF THE
SHOWER AND STORM ACTIVITY SHOULD SUBSIDE BY OR BEFORE DAYBREAK.
THE COLD FRONT WILL APPROACH THE I-55 CORRIDOR AROUND MIDDAY TUESDAY
AND BE THE FOCUS FOR ADDITIONAL STORM DEVELOPMENT BY AFTERNOON.
HOWEVER, ONE LIMITING FACTOR WILL BE HOW LONG CLOUD COVER FROM THE
OVERNIGHT STORMS LINGERS, WHICH WOULD ULTIMATELY LIMIT OUR
DESTABILIZATION POTENTIAL. CAMS SUGGEST DESTABILIZATION WILL BE MOST
LIKELY IN EAST-CENTRAL AND SOUTHEAST ILLINOIS BY MID TO LATE
AFTERNOON IN A MODERATELY SHEARED ENVIRONMENT. HOWEVER, THIS APPEARS
TO BE HIGHLY CONDITIONAL AT THIS POINT. IF STORMS DO DEVELOP,
DAMAGING WINDS, LARGE HAIL, AND HEAVY RAINFALL WILL BE THE PRIMARY
CONCERNS.
A DRIER AND COOLER PERIOD SHAPES UP FOR MIDWEEK AS HIGH PRESSURE
RIDGING SLIDES THROUGH THE UPPER MIDWEST. THIS WILL BE RELATIVELY
SHORT-LIVED AS UPPER TROUGHING MOVES INTO THE CENTRAL US AND
SHORTWAVE ENERGY SENDS SEVERAL ROUNDS OF PRECIPITATION THROUGH
ILLINOIS THIS WEEKEND INTO EARLY NEXT WEEK. WHILE THE SEVERE WEATHER
RISK APPEARS LOW THROUGH THIS PERIOD, BETTER MOISTURE/INSTABILITY
BUILDING BY LATE WEEKEND/EARLY NEXT WEEK WILL SUPPORT
THUNDERSTORMS AT TIMES.
AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/
ISSUED AT 622 PM CDT MON MAY 18 2026
SHOWERS AND THUNDERSTORMS HAVE SETTLED OVER PORTIONS OF
SOUTHERN ILLINOIS THIS EVENING WITH THE NORTHERN EDGE OF THE
PRECIP SHIELD POTENTIALLY CLIPPING THE I-72 CORRIDOR OVER THE
NEXT FEW HOURS. OTHERWISE, ATTENTION TURNS BACK WEST AS THE NEXT
ROUND OF SHOWERS AND STORMS EXPANDS IN COVERAGE ACROSS THE
GREAT PLAINS/MID MISSOURI RIVER VALLEY THIS EVENING. THIS LINE
OF STORMS WILL REACH THE ILLINOIS RIVER VALLEY OVERNIGHT,
WEAKENING AS IT PUSHES INTO CENTRAL ILLINOIS. A FEW SHOWERS OR
WEAK STORMS MAY REACH AS FAR EAST AS THE I-55 CORRIDOR, WITH
CONFIDENCE LOWERING FURTHER EAST. THE WIND FIELD MAY BE
DISRUPTED FOR SEVERAL HOURS BEHIND THE LINE OF STORMS, BUT
GENERALLY FAVORS A SOUTHERLY DIRECTION UNTIL A COLD FRONT COMES
THROUGH TUESDAY AFTERNOON TURNING WINDS OUT OF THE NW. MVFR
CEILINGS WILL ACCOMPANY THE FRONTAL PASSAGE TUESDAY. ONE OTHER
CONCERN FOR TONIGHT WILL BE THE POTENTIAL FOR LLWS AS 40-50 KT
WINDS AROUND 2000 FEET DEVELOP. POOR AGREEMENT BETWEEN THE
MODELS AND THE EXPECTATION FOR SURFACE WINDS TO REMAIN SOMEWHAT
ELEVATED TONIGHT PRECLUDES LLWS MENTION AT THIS TIME.
ILX WATCHES/WARNINGS/ADVISORIES
FLOOD WATCH UNTIL 10 PM CDT THIS EVENING FOR ILZ054>057-
061>063-066>068-071>073.
KEY MESSAGES...NMA
DISCUSSION...NMA
AVIATION...DEUBELBEISS
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