481
FXUS63 KLOT 230712
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
212 AM CDT SAT AUG 23 2025
KEY MESSAGES
- SLIGHT CHANCE (20%) FOR A FEW THUNDERSTORMS THIS AFTERNOON.
- FALL-LIKE TEMPERATURES EARLY/MID NEXT WEEK.
DISCUSSION
ISSUED AT 212 AM CDT SAT AUG 23 2025
PRIMARY FORECAST CONCERN IS A CHANCE OF THUNDERSTORMS THIS
AFTERNOON. A FEW SHOWERS ARE ONGOING ACROSS EAST CENTRAL IA
EARLY THIS MORNING AND ISOLATED SHOWERS WILL BE POSSIBLE ACROSS
NORTHERN IL THIS MORNING, POSSIBLY DEVELOPING OVER THE AREA
AROUND DAYBREAK. THESE ARE EXPECTED TO DISSIPATE THROUGH LATE
MORNING WITH A BRIEF LULL FOR PRECIP CHANCES MIDDAY. THEN AS THE
MAIN COLD FRONT PUSHES ACROSS THE AREA THIS AFTERNOON, THERE
WILL BE A LOW CHANCE (20%) FOR A FEW THUNDERSTORMS, ROUGHLY
ALONG AND EAST OF I-55 AND THEN ENDING BY 00Z. WHILE ITS
POSSIBLE THAT MOST OF THE AREA MAY REMAIN DRY, GIVEN THE SHEAR
ALOFT, IF ANY STORM CAN FORM, IT MAY HAVE THE POTENTIAL TO
PRODUCE LOCALLY GUSTY WINDS.
NORTHWEST WINDS WILL GUST INTO THE MID 20 MPH RANGE BEHIND THE
COLD FRONT THIS AFTERNOON AND THEN DIMINISH WITH SUNSET OVER
LAND BUT CONTINUE TO BE GUSTY OVER SOUTHERN LAKE MICHIGAN. THESE
NORTHWEST WINDS WILL REMAIN GUSTY AT TIMES OVER THE LAKE THROUGH
MONDAY NIGHT, WHICH WILL ALLOW FOR HIGH WAVES AND LIKELY
DANGEROUS SWIMMING CONDITIONS FOR BEACHES AT LEAST ALONG THE
PORTER COUNTY LAKE MICHIGAN SHORE AND WE'LL NEED TO MONITOR FOR
A POSSIBLE BEACH HAZARD STATEMENT.
LAKE EFFECT RAIN SHOWERS WILL BE POSSIBLE SUNDAY NIGHT AND AGAIN
MONDAY NIGHT FOR MAINLY PORTER COUNTY IN NORTHWEST IN, THOUGH
OVERALL CONFIDENCE IS FAIRLY LOW AND WILL BE DEPENDENT ON THE
WIND DIRECTIONS. THERE IS ALSO THE POTENTIAL FOR A FEW
WATERSPOUTS DURING THIS TIME PERIOD THOUGH THE BETTER CONDITIONS
MAY REMAIN TO THE NORTH AND NORTHEAST OF OUR MARINE AREA AND NOT
PLANNING ANY MENTION FOR NOW.
TEMPERATURES WILL TREND COOLER BEHIND THIS COLD FRONT WITH HIGHS
GENERALLY IN THE 70S SUNDAY THROUGH THURSDAY WITH MONDAY LOOKING
TO BE THE COOLEST DAY WITH SOME AREAS POSSIBLY STRUGGLING TO
REACH 70 FOR HIGH TEMPS. OUTSIDE THE CHICAGO URBAN AREA, LOW
TEMPS IN THE 40S LOOK LIKELY MONDAY, TUESDAY AND WEDNESDAY
MORNINGS. CMS
AVIATION /06Z TAFS THROUGH 12Z SUNDAY/
ISSUED AT 1220 PM CDT FRI AUG 22 2025
CONCERNS:
- BRIEF PERIOD OF VFR SHRA POSSIBLE SATURDAY MORNING ALONG A
COLD FRONT NEAR RFD AND NW OF THE CHICAGO TERMINALS, AND
AGAIN NEAR GYY IN THE AFTERNOON.
- BREEZY WNW WINDS WITH GUSTS 20-25 KT THIS AFTERNOON.
A SERIES OF COLD FRONTS WILL SHIFT THROUGH THE TERMINALS TODAY.
THE FIRST WILL TRACK THROUGH MAINLY BEFORE DAYBREAK. EXPECT SOME
LOWER VFR CEILINGS WITH THIS. A FEW SHOWERS WILL OCCUR WITH THE
FIRST WAVE, MAINLY NEAR RFD AND TO THE NW OF THE CHICAGO
TERMINALS IN THE 9Z-12 PERIOD BEFORE DECAYING TO A JUST A CLOUD
DECK.
MOISTURE WILL POOL AHEAD OF THE MAIN COLD FRONT THAT WILL SHIFT
THROUGH LATE MORNING INTO THE AFTERNOON. DEPENDING ON HOW QUICK
THE FRONT WILL GET THROUGH WILL DETERMINE WHETHER ENOUGH
INSTABILITY WILL BUILD ACROSS THE CHICAGO TERMINALS TO TRIGGER A
FEW SHOWERS. CURRENT GUIDANCE WOULD SUGGEST DEVELOPMENT FROM
KMDW SOUTHEASTWARD. HAVE INTRODUCED A PROB30 FOR KGYY GIVEN THE
SIGNAL FOR POSSIBLY A SLIGHTLY FARTHER NW DEVELOPMENT -- AS
EARLIER GUIDANCE SUGGESTED (AND MOST STILL DO) THAT THE CHICAGO
TERMINALS REMAIN DRY GIVEN THAT THE MOISTURE LAYER WILL BE
SOMEWHAT SHALLOW. HOWEVER, A FEW THUNDERSTORMS MAY DEVELOP
ALONG THE ORD SOUTHEAST ARRIVAL TRACK MID TO LATE AFTERNOON.
BREEZY NW WINDS WILL BUILD IN LATE MORNING INTO THE AFTERNOON
WITH GUSTS IN THE LOWER 20S. EXPECT CLEARING TONIGHT AND LIGHTER
NW WINDS.
KMD
LOT WATCHES/WARNINGS/ADVISORIES
IL...NONE.
IN...NONE.
LM...NONE.
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