373
FXUS63 KLOT 221727
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
1227 PM CDT SAT AUG 22 2026
KEY MESSAGES
- ISOLATED TO WIDELY SCATTERED SHOWER OR STORM POSSIBLE (15-20%
CHANCE) THIS AFTERNOON, MAINLY NEAR LAKE MICHIGAN.
- DANGEROUS SWIMMING CONDITIONS EXPECTED AT PORTER COUNTY LAKE
MICHIGAN BEACHES TODAY, THEN AT ALL INDIANA AND COOK COUNTY
LAKE MICHIGAN BEACHES LATE TONIGHT AND SUNDAY.
DISCUSSION
ISSUED AT 236 AM CDT SAT AUG 22 2026
A COLD FRONT IS CURRENTLY ANALYZED ROUGHLY FROM A CHICAGO TO
GALESBURG LINE EARLY THIS MORNING AND IS CONTINUING TO SLOWLY
DRIFT SOUTH AND EAST OUT OF OUR FORECAST AREA. GENERALLY
SPEAKING THE BETTER SHOWER AND THUNDERSTORM COVERAGE AHEAD OF
THE FRONT HAS BEEN IN CENTRAL IL, BUT A COUPLE OF SHOWERS HAVE
BEEN FESTERING IN SOUTHERN NEWTON, JASPER, AND BENTON COUNTIES.
THESE SHOWERS MAY BRIEFLY PRODUCE A ROUGE LIGHTNING STRIKE PRIOR
TO EXITING THESE AREAS OVER THE NEXT HOUR, BUT OTHERWISE DRY
CONDITIONS ARE EXPECTED FOR THE REST OF THE NIGHT.
IN THE WAKE OF THE COLD FRONT, WINDS WILL BECOME NORTHWESTERLY
AND GRADUALLY INCREASE IN SPEED THROUGH THE MORNING WITH GUSTS
EXPECTED TO PEAK AROUND 20-25 MPH (LOCALLY UP TO 30 MPH) THIS
AFTERNOON. THESE NORTHWEST WINDS WILL BUILD WAVES ON LAKE
MICHIGAN TODAY AND RESULT IN DANGEROUS SWIMMING CONDITIONS,
ESPECIALLY INTO PORTER COUNTY, IN BEACHES. AS WIND DIRECTIONS
BECOME MORE NORTHERLY TONIGHT, THE LARGE WAVES ARE FORECAST TO
PIVOT WESTWARD INTO LAKE (IN) COUNTY AND COOK COUNTY BEACHES
OVERNIGHT TONIGHT AND WILL PERSIST THROUGH SUNDAY EVENING. AS A
RESULT, A BEACH HAZARD STATEMENT REMAINS IN EFFECT FOR PORTER
COUNTY, IN STARTING AT 10 AM TODAY AND LASTING THROUGH SUNDAY
EVENING WITH NEW BEACH HAZARD STATEMENT ISSUED FOR LAKE (IN) AND
COOK COUNTIES STARTING LATE TONIGHT THROUGH SUNDAY EVENING. IF
PLANNING TO HEAD TO THE BEACH TODAY MAKE SURE TO CHECK THE SURF
CONDITIONS AND REMEMBER TO STAY DRY WHEN WAVES ARE HIGH!
ASIDE FROM THE BREEZY NORTH-NORTHWEST WINDS TODAY, MOSTLY DRY
CONDITIONS ARE EXPECTED AS DRIER AIR FILTERS INTO THE REGION.
HOWEVER, BROAD UPPER TROUGHING OVER THE GREAT LAKES IS EXPECTED
TO LINGER THROUGH MUCH OF TODAY AND WILL ALLOW THE SHORTWAVE
TROUGH IN NORTHERN WI TO PIVOT OVERHEAD THIS AFTERNOON. WHILE
OVERALL MOISTURE LOOKS TO BE MEAGER TO SAY THE LEAST, FORECAST
SOUNDINGS CONTINUE TO SHOW SOME MODEST INSTABILITY AND SOME LOW-
LEVEL MOISTURE LINGERING NEAR LAKE MICHIGAN WHICH MAY BE
SUFFICIENT TO KICK OFF ISOLATED TO WIDELY SCATTERED SHOWERS AND
PERHAPS A THUNDERSTORM THIS AFTERNOON (15-20% CHANCE). THAT
SAID, NO SEVERE WEATHER IS EXPECTED TODAY AND ANY SHOWERS/STORMS
THAT DO DEVELOP SHOULD WANE AROUND OR SHORTLY AFTER SUNSET.
OTHERWISE, EXPECT MOSTLY TO PARTLY CLOUDY SKIES WITH SEASONABLY
COOL TEMPERATURES IN THE UPPER 70S TO AROUND 80 DEGREES.
THE UPPER TROUGHING WILL GRADUALLY SHIFT INTO THE EASTERN GREAT
LAKES TONIGHT AS HIGH PRESSURE BUILDS INTO THE MIDWEST. THIS
WILL RESULT IN COMPLETELY RAIN-FREE CONDITIONS FOR SUNDAY,
MONDAY AND MOST LIKELY TUESDAY. HOWEVER, CONTINUED NORTHWEST
FLOW WILL KEEP TEMPERATURES ON THE COOLER SIDE FOR THIS TIME OF
YEAR WITH HIGHS SUNDAY AND MONDAY IN THE MID TO UPPER 70S AND
OVERNIGHT LOWS IN THE 50S TO AROUND 60. TEMPERATURES ARE
FORECAST TO MODERATE A BIT ON TUESDAY AS WINDS TURN MORE
SOUTHERLY, BUT HIGHS STILL LOOK TO TOP OUT IN THE UPPER 70S TO
LOWER 80S AT BEST.
WHILE WE ENJOY A WELL DESERVED BREAK IN THE WEATHER, ANOTHER
SHORTWAVE TROUGH IS FORECAST TO BE TRAVERSING ACROSS THE PACIFIC
NORTHWEST AND NORTHERN PLAINS EARLY NEXT WEEK BEFORE PIVOTING
INTO THE GREAT LAKES TOWARDS THE MIDDLE OF THE WEEK. GUIDANCE
CONTINUES TO SHOW THAT A COLD FRONT SHOULD DEVELOP AHEAD OF THIS
SHORTWAVE AND IS PROGGED TO MOVE THROUGH THE REGION SOMETIME
DURING THE WEDNESDAY TO THURSDAY TIMEFRAME. WHILE THERE IS
OVERALL GOOD AGREEMENT ON THIS EVOLUTION AMONGST ENSEMBLE AND
DETERMINISTIC GUIDANCE, THERE IS A LOT OF UNCERTAINTY AROUND
WHEN EXACTLY THE WAVE AND ASSOCIATED FRONT WILL ARRIVE IN
NORTHERN IL AND NORTHWEST IN THUS MAKING THIS PART OF THE
FORECAST LOWER CONFIDENCE. BOTTOM LINE EXPECT TO SEE INCREASING
SHOWER AND THUNDERSTORM CHANCES TOWARDS THE MIDDLE PORTION OF
NEXT WEEK AND KEEP CHECKING BACK FOR MORE SPECIFICS AS WE GET
CLOSER IN TIME. THOUGH, TEMPERATURES SHOULD ALSO BE INCREASING
TOWARDS MORE TYPICAL LATE AUGUST READINGS AHEAD OF THIS SYSTEM
TOO.
YACK
AVIATION /18Z TAFS THROUGH 00Z MONDAY/
ISSUED AT 1227 PM CDT SAT AUG 22 2026
A FEW ISOLATED SHOWERS AND PERHAPS AN ISOLATED THUNDERSTORM ARE
POSSIBLE THIS AFTERNOON, PRIMARILY EAST OF THE CHICAGO
TERMINALS. IF CONFIDENCE INCREASES IN COVERAGE, THEN TAFS MAY
NEED TO BE AMENDED TO INCLUDE A VCSH FOR A FEW HOURS THIS
AFTERNOON. OTHERWISE, LOOK FOR VFR CONDITIONS THROUGH THE TAF
CYCLE.
NORTHWEST WINDS WILL GUST TO AROUND 20 MPH THIS AFTERNOON,
LIKELY EASING AND LOSING GUSTINESS AS SUNSET APPROACHES. LAKE
BREEZE WILL DEVELOP THIS AFTERNOON AND MOVE THROUGH GYY
RESULTING IN A WIND SHIFT TO LIGHTER NE. LAKE BREEZE IS EXPECTED
TO HUG THE SHORE OVER NORTHEAST IL REMAINING EAST OF ORD AND
MDW THROUGH THE AFTERNOON. TOWARD SUNSET, AS WINDS DIMINISH, THE
THE LAKE BREEZE WILL PROBABLY MAKE A RUN WESTWARD TOWARD
ORD/MDW. BEST CHANCE OF A WIND SHIFT TO EASTERLY LOOKS TO BE AT
MDW, BUT CAN'T BE RULED OUT AT ORD.
IF SHOWERS DO DEVELOP NEAR AND OVER THE LAKE THIS AFTERNOON,
OUTFLOW FROM THE SHOWERS COULD PROVIDE THE LAKE BREEZE AN
EARLIER WESTWARD PUSH INLAND. NOT OUT OF THE QUESTION THIS COULD
THREATEN A TEMPORARY EASTERLY WIND SHIFT AT MDW AND POSSIBLY
EVEN ORD LATER THIS AFTERNOON.
- IZZI
LOT WATCHES/WARNINGS/ADVISORIES
IL...BEACH HAZARDS STATEMENT FROM LATE TONIGHT THROUGH SUNDAY
EVENING FOR ILZ103-ILZ104.
IN...BEACH HAZARDS STATEMENT FROM LATE TONIGHT THROUGH SUNDAY
EVENING FOR INZ001.
BEACH HAZARDS STATEMENT THROUGH SUNDAY EVENING FOR INZ002.
LM...SMALL CRAFT ADVISORY FROM 4 AM TO 7 PM CDT SUNDAY FOR WILMETTE
HARBOR TO CALUMET HARBOR IL-CALUMET HARBOR TO GARY IN.
SMALL CRAFT ADVISORY UNTIL 10 PM CDT SUNDAY FOR GARY TO BURNS
HARBOR IN-BURNS HARBOR TO MICHIGAN CITY IN.
VISIT US AT WEATHER.GOV/CHICAGO
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