628
FXUS63 KILX 270208
AFDILX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LINCOLN IL
908 PM CDT SUN APR 26 2026
KEY MESSAGES
- MULTIPLE ROUNDS OF THUNDERSTORMS ARE EXPECTED ON MONDAY. THERE
IS AN ENHANCED RISK (LEVEL 3 OF 5) FOR TORNADOES, DAMAGING
WINDS, AND LARGE HAIL. FLASH FLOODING IS ALSO POSSIBLE.
- WINDY CONDITIONS ARE EXPECTED ON MONDAY, WITH SOUTHERLY GUSTS
UP TO 45 MPH AT TIMES. THIS COULD CAUSE DIFFICULT TRAVEL AND
PERHAPS A BLOWING DUST THREAT FOR AREAS THAT DON'T RECEIVE
ADEQUATE MORNING RAIN.
UPDATE
ISSUED AT 908 PM CDT SUN APR 26 2026
CURRENT FORECAST IS ON TRACK, BUT BASED ON SOME NEWER MODELS,
DECIDED TO MAKE SOME TWEAKS TO THE POPS/WX GRIDS FOR TONIGHT AND
TOMORROW. CHANGES WERE MINOR ENOUGH THAT THE CHANGE TO THE
FORECAST IS MINIMAL AND DOES NOT CHANGE THE MESSAGE. HOWEVER,
UPDATE WILL BE COMING SHORTLY.
DISCUSSION
ISSUED AT 145 PM CDT SUN APR 26 2026
***TODAY***
UPPER ANALYSIS EARLY THIS AFTERNOON SHOWS RIDGING OVER THE EASTERN
US WITH DEEP TROUGHING OVER THE WESTERN CONUS. SURFACE HIGH PRESSURE
IS POSITIONED OFF TO OUR NORTHEAST WITH A DEVELOPING LOW IN THE LEE
OF THE ROCKIES. SOUTH-SOUTHEAST WINDS BETWEEN THESE TWO FEATURES
HAVE ALLOWED TEMPERATURES TO WARM INTO THE 70S EARLY THIS
AFTERNOON. CLOUD COVER WILL INCREASE FROM THE WEST THIS EVENING
AHEAD OF OUR NEXT APPROACHING SYSTEM.
*** MONDAY'S SEVERE WEATHER THREAT / STRONG WINDS ***
A COMPACT SHORTWAVE TROUGH WILL EJECT NORTHWARD TOWARD THE GREAT
LAKES REGION ON MONDAY WITH AN ASSOCIATED SURFACE LOW EXPECTED TO
WORK THROUGH CENTRAL IOWA/SOUTHWEST WISCONSIN BY MONDAY EVENING.
SEVERAL WAVES OF STORMS ARE POSSIBLE THROUGHOUT THE DAY WITH THE
FIRST BEING MONDAY MORNING ALONG A LEADING SHORTWAVE IMPULSE/REMNANT
MCS. CAMS ARE STILL IN DISAGREEMENT ON STORM COVERAGE AND TIMING,
THOUGH THE 12Z GUIDANCE SEEMS TO HAVE FAVORED A LINE SEGMENT
SWEEPING ACROSS THE AREA (NAMNEST, NSSL WRF, ARW). DEPENDING ON
STORM MODE AND COVERAGE, WARM SECTOR RECOVERY MAY BE SLOW BEFORE THE
MAIN SHOW ARRIVES LATE MONDAY AFTERNOON INTO EVENING.
ASSUMING RAPID WARM SECTOR DESTABILIZATION, DEWPOINTS SHOULD CLIMB
INTO THE 60S BY AFTERNOON WITH TEMPERATURES IN THE UPPER 70S. LAPSE
RATES WILL QUICKLY STEEPEN BY AFTERNOON AS MID-LEVEL HEIGHTS FALL
WITH THE APPROACHING UPPER WAVE. INSTABILITY WILL INCREASE FROM WEST
TO EAST AS A 60-70 KT MID-LEVEL JET OVERSPREADS THE AREA AND BOOSTS
OUR WIND SHEAR. FORECAST SOUNDINGS FOR MID TO LATE AFTERNOON SHOW
LARGE CAPE PROFILES, AN INVERTED V SIGNATURE, AND CYCLONICALLY
CURVED HODOGRAPHS. THIS TYPE OF ENVIRONMENT IS FAVORABLE FOR ALL
SEVERE HAZARDS, INCLUDING THE THREAT FOR STRONG TORNADOES.
STORMS SHOULD DEVELOP IN WEST-CENTRAL IL BY LATE AFTERNOON,
INITIALLY TAKING ON A DISCRETE STORM MODE BEFORE GROWING
UPSCALE INTO A LINEAR SEGMENT AS A COLD FRONT IS FORCED IN FROM
THE WEST. THE DAY 2 CONVECTIVE OUTLOOK STILL HOLDS ONTO A LEVEL
3 OF 5 (ENHANCED RISK), WITH A 10%/INTENSITY 2 TORNADO THREAT
(EF3+) AND A LARGE 45% WIND THREAT ACROSS MOST OF THE STATE. THE
HAIL THREAT IS HIGHEST IN THE WEST, COINCIDING WITH ANY
DISCRETE SUPERCELLS THAT DEVELOP EARLY ON. HEAVY RAIN IS ALSO A
THREAT ON MONDAY DUE TO CLIMATOLOGICALLY HIGH PWATS AND
REPEATING STORMS. THE 26.12Z SPC HREF SHOWS A 20-40% CHANCE FOR
LOCALIZED POCKETS OF RAIN AMOUNTS OVER 3", WHICH WOULD EXCEED 6
HOUR FLASH FLOOD GUIDANCE FOR SOME.
STRONG SOUTH WINDS WILL DEVELOP BY MID TO LATE MORNING AS A RESULT
OF THE DEEPENING SURFACE LOW WORKING THROUGH IOWA. GUSTS UP TO
AROUND 45 MPH ARE POSSIBLE, LEADING TO DIFFICULT TRAVEL AND PERHAPS
SOME REDUCED VISIBILITY DUE TO BLOWING DUST. HOWEVER, IF ADEQUATE
RAIN IS OBSERVED WITH MORNING STORMS THE BLOWING DUST THREAT WILL BE
GREATLY MINIMIZED.
*** TUESDAY ONWARD ***
LOW MERIDIONAL FLOW SETS UP HEADING INTO TUESDAY WITH THE COLD FRONT
BEING PUSHED OFF TO THE SOUTH OF THE AREA. A SHORTWAVE TROUGH WILL
WORK THROUGH THE CENTRAL US LATER ON TUESDAY, SPARKING THE
REDEVELOPMENT OF SHOWERS AND STORMS NEAR AND SOUTH OF I-70 TUESDAY
EVENING. THE THREAT FOR SEVERE WEATHER SHOULD STAY JUST OUTSIDE OF
THE AREA, BUT REMAINS CLOSE ENOUGH TO BEAR WATCHING. COOLER
TEMPERATURES WITH OCCASIONAL LOW CHANCES FOR PRECIPITATION (20% OR
LESS) APPEAR LIKELY THROUGH THE REMAINDER OF THE WEEK.
AVIATION /00Z TAFS THROUGH 00Z TUESDAY/
ISSUED AT 643 PM CDT SUN APR 26 2026
VFR CONDITIONS WILL PREVAIL AT ALL SITES THROUGH THE NIGHT WITH
SCATTERED HIGH CLOUDS TONIGHT, FOLLOWED BY BROKEN MID CLOUDS
LATE TONIGHT AS STORMS MOVE INTO THE AREA. WILL HAVE A 4HR
PROB30 GROUP FOR STORMS, BUT CIGS WILL DROP TO AROUND 10KFT LATE
TONIGHT. HOWEVER, CIGS WILL DROP TO AROUND 3.5KFT WHEN STORMS
MOVE IN. THE REST OF THE MORNING AND INTO THE AFTERNOON, MODELS
HAVE A GREAT DEAL OF UNCERTAINTY. WILL KEEP SHRA AND VCTS GOING
FOR REST OF MORNING AND INTO THE AFTERNOON. AFTERNOON STORMS
SHOULD BE FROM SEVERE AND HAVE KEPT +TSRAGR FOR LATE AFTERNOON
AT ALL SITES. WIND WILL BE SOUTHEAST OVERNIGHT, BUT THEN BECOME
SOUTHEAST-SOUTH TOMORROW THROUGH TOMORROW AFTERNOON. WIND SPEEDS
WILL INCREASE TO AROUND 28KTS IN THE MORNING, THEN INCREASING
MORE DURING THE AFTERNOON AND REACHING OVER 30KTS.
ILX WATCHES/WARNINGS/ADVISORIES
NONE.
KEY MESSAGES...NMA
UPDATE...AUTEN
DISCUSSION...NMA
AVIATION...AUTEN
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