781
FXUS63 KLOT 160533
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
1233 AM CDT THU APR 16 2026
KEY MESSAGES
- A BRIEF BREAK IN THE PATTERN IS EXPECTED LATER TODAY THROUGH
THE DAY ON FRIDAY BEFORE ANOTHER STORM SYSTEM AND POTENTIAL
SEVERE WEATHER ARRIVES FRIDAY LATE AFTERNOON AND EVENING.
- 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 /06Z TAFS THROUGH 12Z FRIDAY/
ISSUED AT 1233 AM CDT THU APR 16 2026
FORECAST CONCERNS INCLUDE...
- WIND DIRECTIONS DURING THE EARLY OVERNIGHT HOURS.
- WIND SHIFT TO NORTHEAST THURSDAY AFTERNOON.
- MVFR CIGS OVERNIGHT INTO THURSDAY.
- PERIODIC SHOWER CHANCES.
A LINE OF SHOWERS WITH EMBEDDED THUNDERSTORMS WILL CONTINUE
MOVING AWAY FROM THE TERMINALS THROUGH THE EARLY OVERNIGHT.
THERE WILL BE CONTINUED CHANCES FOR SHOWERS THROUGH THURSDAY
AFTERNOON WITH QUITE A BIT OF UNCERTAINTY FOR TIMING AND HAVE
INCLUDED PROLONGED PERIODS OF VICINITY SHOWER MENTION. IT
APPEARS THE BEST CHANCE FOR ADDITIONAL SHOWERS WILL BE FROM LATE
MORNING THROUGH EARLY AFTERNOON BUT TIMING WILL NEED TO BE
ADJUSTED AS TRENDS EMERGE. AN ISOLATED THUNDERSTORM IS POSSIBLE,
BUT NO MENTION WITH EXPECTED LOW COVERAGE.
PREVAILING WINDS ARE SHIFTING TO THE EAST SOUTHEAST ACROSS
NORTHWEST IL IN THE WAKE OF THE SHOWERS AND THIS SOUTHEAST SHIFT
IS EXPECTED ACROSS THE CHICAGO TERMINALS, AT LEAST FOR A SHORT
TIME, BEFORE WINDS TURN BACK TO THE SOUTHWEST EARLY THIS
MORNING. CONFIDENCE IS LOW FOR SPECIFIC DIRECTIONS AND CHANGES
MAY BE NEEDED. WINDS MAY BEGIN TO GUST INTO THE 20KT RANGE BY
DAYBREAK AS DIRECTIONS SLOWLY TURN MORE WESTERLY THURSDAY
MORNING. CONFIDENCE IS ALSO LOW FOR WINDS THURSDAY AFTERNOON.
DIRECTIONS WILL LIKELY CONTINUE TURNING TO THE NORTHWEST
THURSDAY AFTERNOON AND THEN A LAKE BREEZE BOUNDARY IS EXPECTED
TO MOVE INLAND DURING THE MID/LATE AFTERNOON. TIMING CONFIDENCE
HAS DECREASED AND WILL NEED TO BE REFINED WITH LATER FORECASTS.
WINDS WILL TURN SOUTHEASTERLY THURSDAY EVENING.
PREVAILING MVFR CIGS ARE EXPECTED TO DEVELOP OVERNIGHT,
CONTINUE THURSDAY MORNING THEN LIFT TO VFR THURSDAY AFTERNOON.
HOWEVER, LOW CIGS ARE POSSIBLE WITH THE LAKE BREEZE BOUNDARY. IN
ADDITION, THERE WILL LIKELY BE FOG OVER LAKE MICHIGAN AND SOME
OF THE MODEL GUIDANCE IS SPREADING THIS FOG INLAND THURSDAY
EVENING AND ACROSS THE CHICAGO TERMINALS EARLY FRIDAY MORNING.
CONFIDENCE IS TOO LOW TO INCLUDE ANY LOWER CIGS OR FOG FOR
ORD/MDW IN THEIR NEW 30 HOUR TAFS AND TRENDS WILL NEED TO BE
MONITORED. 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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