926
FXUS63 KILX 191730
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
1230 PM CDT TUE MAY 19 2026
KEY MESSAGES
- A WEAKENING LINE OF STORMS WILL MOVE THROUGH CENTRAL ILLINOIS
THIS MORNING, BRINGING A LOW (LESS THAN 15% CHANCE) RISK OF
DAMAGING WINDS OR HAIL.
- ADDITIONAL STORMS MAY DEVELOP NEAR INTERSTATE 70 AROUND
MIDDAY, THREATENING THE AREA WITH DAMAGING WINDS, LARGE HAIL,
AND TORRENTIAL RAINFALL.
- SATURATED GROUND FROM RECENT HEAVY RAINS CREATES A LINGERING
FLASH FLOOD RISK NEAR INTERSTATE 70, THOUGH THE CHANCE OF
EXCEEDING FLOODING RAINFALL RATES IS LOW (20% OR LESS).
DISCUSSION
ISSUED AT 318 AM CDT TUE MAY 19 2026
REMNANTS OF A LINEAR MCS PERSIST OVER WEST-CENTRAL ILLINOIS
EARLY THIS MORNING. WHILE THE ACTIVITY HAS GENERALLY REMAINED
SUB-SEVERE, THE MESOSCALE ENVIRONMENT REMAINS CAPABLE OF
PRODUCING OCCASIONAL DAMAGING WIND GUSTS. SUSTENANCE OF THE
CURRENT RAGGED CONVECTIVE LINE IS BEING SUPPORTED BY
APPROXIMATELY 30-35 KTS OF EFFECTIVE LAYER SHEAR, DRIVEN BY A
50-60 KT LOW-LEVEL JET (LLJ) CORE VEERING IN AHEAD OF THE
SYSTEM.
THERMODYNAMIC PROFILES AHEAD OF THE LINE ARE CHARACTERIZED BY
MODEST MUCAPE NEAR 1500 J/KG, SUPPORTED BY FAVORABLE MID-LEVEL
LAPSE RATES EXCEEDING 7 C/KM, SUGGESTING THAT ISOLATED LARGE
HAIL CANNOT BE ENTIRELY DISCOUNTED. THE POTENTIAL FOR LOCALIZED
DOWNBURSTS REMAINS A FOCUS AS DCAPE VALUES OVER 1000 J/KG
COMBINED WITH LOCALIZED EVAPORATIVE COOLING AND MID-LEVEL DRY
AIR COULD OCCASIONALLY BREACH THE MORNING INVERSION. CONVERSELY,
THE TORNADO RISK IS CONSIDERED MINIMAL DUE TO MARGINAL LOW-
LEVEL SHEAR AND AN UNFAVORABLE STORM-RELATIVE VECTOR
ORIENTATION. NEVERTHELESS, CONVECTION SHOULD CONTINUE THROUGH
THE LATE MORNING AS IT NEARS THE I-55 CORRIDOR, THOUGH IT IS
EXPECTED TO WEAKEN AS THE PRIMARY MID-LEVEL SHORTWAVE MOVES
NORTH OF I-80 AND THE LLJ RECEDES.
REGARDING PRECIPITATION, RAINFALL RATES HAVE REMAINED MODEST.
MRMS DATA INDICATES ONE-HOUR RATES GENERALLY AT OR BELOW ONE
INCH, A TREND SUPPORTED BY HIGH-RESOLUTION GUIDANCE AS THE LINE
CONTINUES ITS GRADUAL DECAY THROUGH THE MORNING HOURS.
CONVECTIVE REDEVELOPMENT IS EXPECTED TO REMAIN SUPPRESSED NORTH
OF INTERSTATE 72 FOR THE REST OF THE DAY, CONSISTENT WITH THE
STABILIZATION CAUSED BY THIS MORNINGS CONVECTIVE DEBRIS. THE
AREA NEAR AND SOUTH OF I-70 PRESENTS THE MAIN CONCERN FOR LATER
TODAY DUE TO A HIGHER POTENTIAL FOR DESTABILIZATION. MORNING
CONVECTIVE OUTFLOWS ARE NOT EXPECTED TO REACH THIS SOUTHERN
REGION UNTIL APPROXIMATELY NOON (17Z). HREF DATA INDICATES ABOUT
2000 J/KG OF SBCAPE IN THIS VICINITY, WHICH, WHEN COMBINED WITH
A SUBTLE MID-LEVEL SHORTWAVE, COULD INCREASE EFFECTIVE-LAYER
SHEAR TO NEAR 30 KTS. THESE CONDITIONS MAY BRIEFLY REINVIGORATE
CONVECTIVE OUTFLOWS, POTENTIALLY RESULTING IN DAMAGING WINDS,
LARGE HAIL, AND TORRENTIAL RAINFALL.
A HEAVY RAINFALL POTENTIAL IS PARTICULARLY CONCERNING GIVEN THE
WET ANTECEDENT CONDITIONS, WITH RECENT OBSERVATIONS OF 3-4
INCHES OF RAIN ACROSS PORTIONS OF EFFINGHAM, CLAY, AND JASPER
COUNTIES. FLASH FLOOD GUIDANCE INDICATES THAT RAINFALL EXCEEDING
1.25 INCHES PER HOUR TODAY COULD TRIGGER WIDESPREAD FLOODING.
WHILE CURRENT HREF GUIDANCE SUGGESTS A LOW PROBABILITY (20% OR
LESS) OF REACHING THESE RATES, THE RISK REMAINS A FOCAL POINT
DUE TO THE SATURATED GROUND.
SCATTERED SHOWERS MAY LINGER ACROSS SOUTHEAST ILLINOIS THROUGH
WEDNESDAY MORNING, WITH INCREASED BAROCLINICITY/FRONTOGENESIS
BEHIND THE DEPARTED COLD FRONT. RAINFALL AMOUNTS WOULD BE LIGHT
SHOULD THIS OCCUR, AND THE CHANCES WILL BE FLEETING AS A DRIER,
COOLER CONTINENTAL AIR MASS SETTLES OVER THE MIDWEST.
PRECIPITATION IS EXPECTED TO RETURN BY FRIDAY FOLLOWING A BRIEF
PERIOD OF SEASONABLY COOL CONDITIONS. AS SURFACE HIGH PRESSURE
SHIFTS TO THE EAST, A ROBUST MID-LEVEL SHORTWAVE IS FORECAST TO
TRACK INTO THE CENTRAL UNITED STATES. THIS PATTERN,
CHARACTERIZED BY A STEADY STREAM OF GULF MOISTURE AND A SERIES
OF MINOR IMPULSES ORIGINATING FROM THE SOUTHERN PLAINS, WILL
KEEP CENTRAL ILLINOIS SUSCEPTIBLE TO MULTIPLE ROUNDS OF
SCATTERED SHOWERS. WHILE WEAK KINEMATIC PROFILES SHOULD LARGELY
MITIGATE THE RISK OF SEVERE WEATHER, A GRADUAL INCREASE IN
INSTABILITY OVER THE WEEKEND MAY SUPPORT THE DEVELOPMENT OF
SCATTERED THUNDERSTORMS.
AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/
ISSUED AT 1230 PM CDT TUE MAY 19 2026
WEST-SOUTHWEST WINDS WILL SHIFT TO THE NORTH-NORTHWEST AS A COLD
FRONT WORKS THROUGH THE AREA. A SHORT PERIOD OF MVFR CEILINGS WILL
FILL BEHIND THE FRONT WITH ABOUT A 60-80% CHANCE OF OCCURRENCE
AT ALL AIRFIELDS EXCEPT KCMI. AFTERNOON/EVENING THUNDERSTORM
CHANCES WILL REMAIN SOUTH OF ALL AIRFIELDS WITH PERHAPS JUST A
LOW CHANCE (<20%) FOR ISOLATED SHOWERS THROUGH THIS EVENING.
WINDS CONTINUE TO VEER TO THE NORTH BY WEDNESDAY MORNING WITH
CLOUDS SLOWLY LIFT FROM WEST TO EAST THROUGH THE DAY.
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
KEY MESSAGES...MJA
DISCUSSION...MJA
AVIATION...NMA
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