209
FXUS63 KLOT 152346
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
646 PM CDT WED APR 15 2026
KEY MESSAGES
- ADDITIONAL PERIOD OF SHOWERS AND THUNDERSTORMS EXPECTED THIS
EVENING. SOME COULD BE STRONG AND PRODUCE HEAVY RAINFALL
LEADING TO LOCALIZED FLASH FLOODING.
- A BRIEF BREAK IN THE PATTERN IS EXPECTED LATE THURSDAY INTO
THE DAY ON FRIDAY BEFORE ANOTHER STORM SYSTEM ARRIVES FRIDAY
EVENING INTO EARLY SATURDAY.
- COOLER AIR ARRIVES INTO EARLY NEXT WEEK AND MAY BRING
FROST/FREEZE CONCERNS EARLY SUNDAY AND MONDAY MORNINGS.
DISCUSSION
ISSUED AT 257 PM CDT WED APR 15 2026
THROUGH THURSDAY...
THE PRIMARY WEATHER FOCUS IN THE NEAR CONTINUES TO REVOLVE
AROUND THE EXPECTATION FOR ADDITIONAL ROUNDS OF SHOWERS AND
THUNDERSTORMS, PARTICULARLY THIS EVENING.
A RECENT SURFACE ANALYSIS INDICATES THAT AN AREA OF LOW
PRESSURE RESIDES ACROSS SOUTHEASTERN NE, WITH AN ASSOCIATED
SURFACE COLD FRONT EXTENDING SOUTH-SOUTHWESTWARD INTO THE TX
PANHANDLE. WHILE OUR AREA HAS REMAINED CLOUDY, INCREASED
INSOLATION WEST OF THE AREA IN THE VICINITY OF THE SURFACE LOW
AND FRONTAL BOUNDARY CONTINUES TO DESTABILIZE THE VERY MOIST
(DEW POINTS IN THE LOW TO MID 60S) LOW-LEVEL PREFRONTAL AIRMASS
ACROSS MO INTO SOUTH CENTRAL IA. THIS WILL SET THE STAGE FOR
ADDITIONAL THUNDERSTORM DEVELOPMENT MID TO LATE THIS AFTERNOON
WEST OF OUR AREA AS INCREASED FORCING FOR ASCENT ASSOCIATED WITH
THE MID-LEVEL IMPULSE EJECTING INTO THE MID-MISSOURI VALLEY
OVERSPREADS THE FRONTAL BOUNDARY. AFTER STORMS ONSET, A GRADUAL
UPWARD GROWTH INTO AN MCS IS ANTICIPATED THIS EVENING AS THEY
SHIFT EASTWARD ACROSS THE MISSISSIPPI RIVER. IT APPEARS THE
PRIMARY SEVERE WEATHER THREAT WITH THESE STORMS WILL BE WEST OF
OUR AREA, WITH STORMS LIKELY TO BE ON A WEAKENING TREND AS THEY
PROGRESS EASTWARD ACROSS NORTHERN IL DURING THE MID TO LATE
EVENING HOURS. NEVERTHELESS, A CONTINUED FAVORABLE KINEMATIC
ENVIRONMENT OVERHEAD MAY CONTINUE TO SUPPORT A THREAT FOR
LOCALIZED STRONG WIND GUSTS WITH THE WEAKENING LINE OF STORMS.
HEAVY RAINFALL IS EXPECTED TO ACCOMPANY THESE STORMS THROUGH
THE EVENING, AND THIS DOES CONTINUE TO ADD CONCERNS FOR POSSIBLE
HYDRO CONCERNS TONIGHT. HOWEVER, IT APPEARS THE HEAVIEST RAIN
RATES MAY REMAIN MORE PROGRESSIVE WITH THE MOVING LINE OF STORMS
TONIGHT. ACCORDINGLY, IT APPEARS THE THREAT FOR SIGNIFICANT
FLASH FLOODING IS LOWER THAN PREVIOUSLY THOUGHT. NEVERTHELESS,
AREAS ACROSS FAR NORTHERN IL THAT RECEIVED HEAVY RAINFALL LAST
NIGHT WILL BE MOST AT RISK FOR ADDITIONAL FLOODING CONCERNS.,
WITH THIS IN MIND, WE HAVE OPTED TO HOLD ONTO THE GOING FLASH
FLOOD WATCH FOR THIS EVENING.
SHOWER AND THUNDERSTORM COVERAGE IS EXPECTED TO BECOME MORE
WIDELY SCATTERED OVERNIGHT TONIGHT INTO THURSDAY AS THE MAIN
MID-LEVEL IMPULSE SHIFTS OVERHEAD. AS AN AFTERNOON LAKE BREEZE
DEVELOPS AND PUSHES INLAND ACROSS NORTHEASTERN IL AND
NORTHWESTERN IN THURSDAY AFTERNOON IN THE WAKE OF THE SURFACE
LOW, THIS MAY ACT AS A FOCUS FOR ADDITIONAL ISOLATED SHOWER
ACTIVITY FOR A FEW HOURS THURSDAY AFTERNOON. OUTSIDE OF THIS,
CONDITIONS WILL BE DRYING OUT THURSDAY AFTERNOON AND EVENING.
KJB
FRIDAY - SATURDAY:
STRONG SOUTHERLY WARM AND MOIST CONVECTION WILL RETURN INTO THE
DAY ON FRIDAY AHEAD OF AN APPROACHING COLD FRONT. THIS BOUNDARY
IS EXPECTED TO PROGRESS ACROSS THE AREA SOMETIME LATE FRIDAY
INTO EARLY SATURDAY MORNING PAIRED WITH A LINE OF THUNDERSTORMS,
SOME OF WHICH COULD BE SEVERE. SUSPECT THAT LESS FAVORABLE
DIURNAL TIMING OF ANY LINGERING STORMS INTO THE MORNING ON
SATURDAY MAY LIMIT THE OVERALL SEVERE THREAT HERE LOCALLY BEFORE
STORMS REINTENSIFY EAST OF THE AREA INTO THE REST OF THE DAY.
STAY TUNED!
SATURDAY NIGHT ONWARD:
IN THE WAKE OF THE EARLY SATURDAY COLD FRONT, A MUCH COLDER
AIRMASS (RELATIVE TO WHAT WE HAVE HAD OVER THE PAST SEVERAL
DAYS) WILL SETTLE INTO THE REGION OVER THE WEEKEND. OVERNIGHT
LOW TEMPERATURES MAY DROP INTO THE 30S, WITH SOME NEAR TO SUB-
FREEZING TEMPERATURES POSSIBLE ACROSS INTERIOR NORTHERN
ILLINOIS. LIGHTER WINDS IN PLACE SUNDAY NIGHT MAY ALLOW FOR
FROST DEVELOPMENT OUTSIDE OF CHICAGO AND WILL BE SOMETHING FOR
THOSE WITH AGRICULTURAL INTERESTS TO MONITOR OVER THE NEXT FEW
DAYS.
THE COOLER CONDITIONS WILL BE RATHER SHORT-LIVED WITH EXTENDED
GUIDANCE FAVORING A RETURN TOWARD HIGH AMPLITUDE RIDGING ACROSS
THE CENTRAL CONUS AND UNSEASONABLY WARM TEMPERATURES RETURNING
TO THE REGION BY MIDWEEK NEXT WEEK.
PETR
AVIATION /00Z TAFS THROUGH 06Z FRIDAY/
ISSUED AT 646 PM CDT WED APR 15 2026
FORECAST CONCERNS INCLUDE...
SCATTERED THUNDERSTORMS THIS EVENING.
POSSIBLE WIND SHIFT TO EAST/SOUTHEAST BEHIND STORMS.
MVFR CIGS/PERIODIC SHOWERS OVERNIGHT THROUGH THURSDAY AFTERNOON.
WIND SHIFT TO NORTHEAST EARLY THURSDAY AFTERNOON.
CURRENT SHOWERS AND A FEW THUNDERSTORMS OVER FAR NORTHWEST IL
ARE EXPECTED TO SLOWLY INCREASE IN COVERAGE OVER THE NEXT FEW
HOURS AND FORM A BROKEN LINE AND MOVE ACROSS THE REST OF THE
AREA DURING THE LATE EVENING HOURS AND LIKELY BE WEAKENING SOME
AS THEY MOVE ACROSS THE CHICAGO METRO AREA. CURRENT TEMPO TIMING
SEEMS ON TRACK FOR THE CHICAGO TERMINALS WITH PERHAPS A FEW
SHOWERS PRIOR TO THIS ACTIVITY. ADDITIONAL SHOWERS ARE EXPECTED
IN THE EARLY OVERNIGHT HOURS WITH ADDITIONAL SHOWERS POSSIBLE
FROM MID MORNING THURSDAY THROUGH EARLY THURSDAY AFTERNOON.
SOUTH/SOUTHWEST WINDS MAY GUST AS HIGH AS THE MID 20KT RANGE
THIS EVENING WITH DIRECTIONS PERHAPS FAVORING MORE SOUTHERLY
FOR THE NEXT FEW HOURS THEN TURNING MORE TO THE SOUTHWEST BY MID
EVENING. CONFIDENCE IS LOW FOR WIND DIRECTIONS BEHIND THE
EXPECTED AREA OF THUNDERSTORMS LATER THIS EVENING. SOME OF THE
MOST RECENT GUIDANCE TURNS WINDS SOUTHEASTERLY AND OPTED FOR A
170 DIRECTION FOR NOW, BUT CHANGES TO WINDS CAN BE EXPECTED
WITH LATER FORECASTS AND UPDATES. WINDS WILL TURN MORE SOUTHWEST
BY DAYBREAK, WESTERLY THURSDAY MORNING AND THEN SHIFT TO THE
NORTHEAST AS A LAKE BREEZE/FRONT MOVES INLAND. EARLY THURSDAY
AFTERNOON TIMING LOOKS GOOD BUT SPECIFIC TIMING WILL NEED SOME
REFINEMENT AS TRENDS EMERGE.
MVFR CIGS WILL BE POSSIBLE WITH ANY SHOWERS OR THUNDERSTORMS
THIS EVENING THEN PREVAILING MVFR CIGS ARE EXPECTED TO DEVELOP
OVERNIGHT AND CONTINUE THROUGH EARLY AFTERNOON THURSDAY WITH
SOME UNCERTAINTY FOR HOW FAST CIGS MAY LIFT DURING THE
AFTERNOON. CMS
LOT WATCHES/WARNINGS/ADVISORIES
IL...FLOOD WATCH UNTIL 1 AM CDT THURSDAY FOR ILZ003-ILZ004-ILZ005-
ILZ006-ILZ008-ILZ010-ILZ011-ILZ012-ILZ013-ILZ019-ILZ020-
ILZ021-ILZ023-ILZ032-ILZ103-ILZ104-ILZ105-ILZ106-ILZ107-
ILZ108.
IN...FLOOD WATCH UNTIL 1 AM CDT THURSDAY FOR INZ001-INZ002-INZ010-
INZ011.
LM...NONE.
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