391
FXUS63 KILX 092304
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
604 PM CDT TUE JUN 9 2026
KEY MESSAGES
- SLOW MOVING THUNDERSTORMS WILL BRING A LOCALIZED RISK OF 2-3
INCHES OF HEAVY RAIN TO PORTIONS OF CENTRAL ILLINOIS THIS
AFTERNOON THROUGH TONIGHT. A FEW STRONGER STORMS COULD ALSO
PRODUCE ISOLATED DAMAGING WIND GUSTS.
- SEVERE THUNDERSTORMS WILL IMPACT THE REGION WEDNESDAY
AFTERNOON THROUGH THURSDAY NIGHT. DAMAGING STRAIGHT-LINE WINDS
ARE THE PRIMARY HAZARD, BUT THERE REMAINS A LESSER THREAT OF
HAIL AND AN ISOLATED TORNADO.
- HIGH TEMPERATURES IN THE 90S WILL DRIVE HEAT INDEX VALUES INTO
THE UPPER 90S AND LOWER 100S WEDNESDAY AND THURSDAY. THERE IS
A 20 TO 30 PERCENT CHANCE FOR HEAT INDEX VALUES IN EXCESS OF
100.
DISCUSSION
ISSUED AT 110 PM CDT TUE JUN 9 2026
NEAR-TERM OUTLOOK: UNSETTLED PATTERN...
THE FORECAST AREA IS LOCKED INTO AN UNSETTLED WEATHER PATTERN,
FEATURING NEARLY DAILY OPPORTUNITIES FOR SHOWER AND THUNDERSTORM
DEVELOPMENT THROUGH THE UPCOMING WEEKEND. THIS AFTERNOON, A
REMNANT MESOSCALE CONVECTIVE VORTEX (MCV) IS TRACKING EASTWARD
NEAR THE I-72 CORRIDOR. CONVECTION IS CURRENTLY INTENSIFYING
WITHIN THE WARM ADVECTION WING JUST NORTH OF THE MCVS TRACK. SPC
MESOANALYSIS REVEALS UNCAPPED MLCAPE VALUES OF 1500-2500 J/KG
AHEAD OF THIS FEATURE; HOWEVER, EFFECTIVE SHEAR REMAINS MODEST
AT 20-25 KT. WHILE WEAK SHEAR MAY LIMIT ORGANIZED STORM
LONGEVITY, LOCALIZED GUSTY WINDS AND SLOW-MOVING OR TRAINING
CONVECTIVE ELEMENTS PRESENT A THREAT FOR RAINFALL SWATHS OF 2-3
INCHES. FARTHER SOUTH, NEAR AND SOUTH OF I-70, A REMNANT OUTFLOW
BOUNDARY IS INITIATING ISOLATED ACTIVITY WITHIN AN AXIS OF
HIGHER INSTABILITY, POSING A LIMITED SEVERE THREAT PRIMARILY
DRIVEN BY DAMAGING WIND POTENTIAL.
AS WE MOVE INTO TONIGHT, SOUTHWEST FLOW ALOFT WILL REESTABLISH
ACROSS THE REGION, SUPPORTED BY A STRENGTHENING LOW-LEVEL JET IN
THE MID-MISSOURI VALLEY. WHILE THE MOST ROBUST INSTABILITY
REMAINS FOCUSED TO OUR WEST, THE GRADIENT EXTENDS INTO PORTIONS
OF CENTRAL ILLINOIS, DRIVING A WARM AIR ADVECTION-DRIVEN CHANCE
FOR SHOWERS AND STORMS THAT SHOULD SHIFT NORTHEAST OF THE
FORECAST AREA BY DAYBREAK WEDNESDAY.
MID-WEEK HEAT AND SEVERE POTENTIAL...
WEDNESDAY AND THURSDAY WILL FEATURE WIDESPREAD TEMPERATURES IN
THE 90S, WITH HEAT INDICES CLIMBING INTO THE UPPER 90S TO LOWER
100S. AT THIS TIME, CONFIDENCE IN MEETING HEAT ADVISORY CRITERIA
(MAX HEAT INDEX NEAR 105F) REMAINS LOW, WITH LREF PROBABILITIES
FOR HEAT INDICES EXCEEDING 100F GENERALLY HOLDING IN THE 20-30
PERCENT RANGE FOR AREAS SOUTH OF I-70 ON WEDNESDAY AND SOUTH OF
A RUSHVILLE TO TERRE HAUTE LINE ON THURSDAY. THE PRIMARY
LIMITING FACTORS FOR HIGHER HEAT READINGS WILL BE CLOUDS AND
LINGERING CONVECTIVE DEBRIS.
BY WEDNESDAY AFTERNOON, CENTRAL ILLINOIS WILL RESIDE FIRMLY
WITHIN THE WARM SECTOR AS A WARM FRONT SURGES NORTHWARD INTO
WISCONSIN, ACCOMPANIED BY BREEZY SOUTH TO SOUTHWEST WINDS. WHILE
MODEST CAPPING AND DISPLACEMENT FROM THE PRIMARY FORCING SHOULD
MAINTAIN A LARGELY DRY FIRST HALF OF THE DAY, WE ARE MONITORING
TWO WAVES OF POTENTIAL THUNDERSTORM DEVELOPMENT ORIGINATING IN
IOWA AND MISSOURI. THESE COMPLEXES MAY GROW UPSCALE AND TRAVERSE
PORTIONS OF CENTRAL ILLINOIS FROM MID-AFTERNOON THROUGH LATE
EVENING. WITH MLCAPE VALUES PROJECTED TO EXCEED 2000 J/KG, DEEP-
LAYER SHEAR WILL BE SUFFICIENT TO SUPPORT SEVERE STORMS. LINEAR
STORM MODES SUGGEST WIND WILL BE THE PRIMARY HAZARD, THOUGH THE
ENVIRONMENT REMAINS SUPPORTIVE OF HAIL AND THE POTENTIAL FOR AN
ISOLATED TORNADO.
LATE-WEEK TRANSITION AND WEEKEND OUTLOOK...
A ROBUST SHORTWAVE TROUGH IS EXPECTED TO LIFT INTO THE UPPER
MIDWEST ON THURSDAY, FINALLY DRIVING A COLD FRONT THROUGH
CENTRAL ILLINOIS BY THURSDAY EVENING AND OVERNIGHT. AHEAD OF
THIS BOUNDARY, THE GFS SUGGESTS A BROAD, UNSTABLE WARM SECTOR
WITH MLCAPE VALUES EXCEEDING 3000 J/KG. COUPLED WITH DEEP-LAYER
SHEAR OF 25-35 KT AND 0-1KM SHEAR OF 15-25 KT, THE KINEMATIC
ENVIRONMENT IS SEASONABLY STRONG. WHILE PRE-FRONTAL DISCRETE
ACTIVITY WITH ALL SEVERE HAZARDS IS POSSIBLE, THE PRIMARY
CONCERN REMAINS STRAIGHT-LINE WINDS AS CONVECTIVE ELEMENTS
CONGEAL INTO A LINE ALONG AND AHEAD OF THE FRONT.
LINGERING SHOWERS AND STORMS OVER SOUTHEAST ILLINOIS ON FRIDAY
MORNING WILL QUICKLY EXIT, GIVING WAY TO CLEARING SKIES AS HIGH
PRESSURE BUILDS INTO THE REGION. THIS WILL PROVIDE A BRIEF
RETURN TO MORE SEASONAL CONDITIONS, WITH HIGHS IN THE LOWER TO
MID-80S AND DEW POINTS MIXING DOWN INTO THE UPPER 50S.
FOR THE WEEKEND AND INTO EARLY NEXT WEEK, THE PATTERN TURNS
MORE ZONAL ALOFT WHILE A LOW-LEVEL BAROCLINIC ZONE WOBBLES OVER
THE REGION. THIS SETUP MAINTAINS ADDITIONAL CHANCES FOR SHOWERS
AND THUNDERSTORMS, THOUGH SPECIFICS REGARDING TIMING AND
COVERAGE REMAIN UNCERTAIN AT THIS FORECAST RANGE.
AVIATION /00Z TAFS THROUGH 00Z THURSDAY/
ISSUED AT 601 PM CDT TUE JUN 9 2026
ONGOING SCT TSRA HAVE PUSHED EAST OF KCMI, AND THE TERMINALS
SHOULD STAY DRY THROUGH 06Z. TWO ADDITIONAL ROUNDS OF CONVECTION
ARE POSSIBLE THIS PERIOD, THE FIRST BEING BETWEEN 07-10Z AND THE
OTHER BEING AFTER 20Z WED. MVFR CEILINGS AND VIS ARE POSSIBLE
WITH ANY STORMS, OTHERWISE, VFR CONDITIONS SHOULD PREVAIL.
SOUTHWESTERLY WINDS WILL BECOME BREEZY DURING THE DAY ON WED,
WITH PEAK GUSTS APPROACHING 25 KTS WED AFTERNOON.
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
KEY MESSAGES...DEUBELBEISS
DISCUSSION...DEUBELBEISS
AVIATION...ERWIN
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