064
FXUS63 KLOT 231138
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
638 AM CDT WED SEP 23 2026
KEY MESSAGES
- ISOLATED SPRINKLES POSSIBLE EARLY THIS MORNING, OTHERWISE
MOSTLY CLOUD, BREEZY AND DRY CONDITIONS EXPECTED TODAY.
- GENERALLY SLIGHTLY BELOW TO BELOW AVERAGE TEMPERATURES
EXPECTED INTO AT LEAST THE FIRST PART OF THE UPCOMING
WEEKEND.
DISCUSSION
ISSUED AT 158 AM CDT WED SEP 23 2026
LOOPING THE REGIONAL RADAR MOSAIC SINCE LAST EVENING INDICATES
THAT THE MID-LEVEL VORT ASSOCIATED WITH AN UPPER-LEVEL LOW WAS
CENTERED JUST WEST-SOUTHWEST OF CHICAGO EARLY THIS MORNING. THIS
FEATURE APPEARS TO BE BECOMING MORE SHEARED IN RESPONSE TO A
STRONGER MID- LEVEL SHORT WAVE TRACKING SOUTHEAST FROM SOUTHERN
IA INTO NORTHEAST MO AND WEST-CENTRAL IL. ISOLATED/WIDELY
SCATTERED SHOWERS BENEATH THE CENTER OF THE ORIGINAL VORT HAVE
DISSIPATED OVER THE LAST FEW HOURS, THOUGH HAVE MAINTAINED SOME
DECREASING SLIGHT CHANCE (15-20%) POPS NEAR THE CENTER OF THE
CIRCULATION DURING THE PREDAWN HOURS IN CASE ANYTHING
REDEVELOPS. CAN'T COMPLETELY RULE OUT SOME ISOLATED SPRINKLES OR
EVEN PATCHY DRIZZLE ACROSS THE EAST/SOUTHEAST PARTS OF THE CWA
THIS MORNING AS THE SHEARING VORT CONTINUES TO DRIFT SLOWLY OFF
TO THE EAST-SOUTHEAST, THOUGH RATHER SHALLOW MOISTURE PROFILES
IN FORECAST SOUNDINGS INDICATE LITTLE SUBSTANTIAL PRECIP THREAT.
EXTENSIVE (BUT SHALLOW) LOW-LEVEL CLOUD DECK WAS NOTED IN GOES
IMAGERY SPREADING WESTWARD ACROSS THE FORECAST AREA HOWEVER, AND
THIS SHOULD MAINTAIN CLOUDY/MOSTLY CLOUDY SKIES ACROSS THE AREA
TODAY, ESPECIALLY ACROSS THE SOUTHERN HALF/TWO THIRDS OF THE
AREA. CLOUD COVER AND STILL-BREEZY NORTHEAST WINDS WILL KEEP
TEMPERATURES ON THE COOL SIDE ONCE AGAIN, WITH HIGHS IN THE
MID-60S FOR MOST AREAS.
WITH OUR MID-LEVEL SHORT-WAVE ENERGY SLOWLY TRACKING OFF TO THE
SOUTHEAST OF THE REGION THOUGH THE END OF THE WEEK, WE'LL SEE
UPPER RIDGING DEVELOP INTO THE WESTERN GREAT LAKES REGION
(THOUGH TEMPERED BY THE PASSAGE OF A MID-LEVEL SHORT WAVE ALONG
THE U.S.CANADIAN BORDER THURSDAY NIGHT INTO FRIDAY). THIS WILL
ALLOW THE WESTERN PERIPHERY OF THE ELONGATED SURFACE RIDGE TO
OUR NORTH SETTLE ACROSS THE AREA, AND WILL MAINTAIN DRY AND
SEASONABLY COOL WEATHER CONDITIONS ALONG WITH DIMINISHING WINDS
FOR THE LOCAL AREA.
EVOLUTION OF A DEEP CUT-OFF LOW ALONG THE EAST COAST BY THE
WEEKEND WILL TEND TO SET UP A BLOCKY UPPER-AIR PATTERN ACROSS
THE EASTERN CONUS, PREVENTING MUCH IN THE WAY OF SIGNIFICANT
PRECIPITATION CHANCES FOR THE FORECAST AREA. GUIDANCE DOES
DEPICT ANOTHER MORE AMPLIFIED SHORT-WAVE PROPAGATING INTO THE
UPPER MIDWEST THIS WEEKEND, WITH THE POTENTIAL FOR A (LIKELY)
DECAYING AREA OF PRECIP TO APPROACH THE FORECAST AREA LATE
SATURDAY NIGHT/EARLY SUNDAY. THIS WAVE WILL BE PUSHING INTO THE
UPPER RIDGE AND FIGHTING DRIER LOW- LEVEL AIR, HOWEVER. GLOBAL
ENSEMBLE POPS REMAIN FOCUSED THE MISSISSIPPI RIVER THROUGH THE
WEEKEND. THE NBM INITIALIZED WITH SOME LOW-CHANCE POPS ACROSS
OUR WESTERN CWA LATE SATURDAY NIGHT/EARLY AND MADE NO CHANGES,
THOUGH IT DOESN'T LOOK LIKE A SIGNIFICANT RAIN THREAT FOR THE
DAYTIME WEEKEND HOURS. A GRADUAL MODEST WARM-UP BACK TO AVERAGE
TEMPS (LOW/MID 70S) IS EXPECTED LATER IN THE WEEKEND INTO EARLY
NEXT WEEK. EXTENDED GUIDANCE/ENSEMBLES EVENTUALLY EJECT THE DEEP
EAST COAST CUT-OFF LOW OFF TO THE NORTHEAST MONDAY/TUESDAY,
WITH THE NEXT CHANCE OF ANY SIGNIFICANT PRECIP LIKELY HOLDING
OFF UNTIL THE MIDDLE OF NEXT WEEK.
RATZER
AVIATION /12Z TAFS THROUGH 18Z THURSDAY/
ISSUED AT 638 AM CDT WED SEP 23 2026
PRIMARY FORECAST CONCERN IS MVFR CIGS LATER THIS MORNING THROUGH
EARLY THIS EVENING. MVFR CIGS ACROSS SOUTHERN LOWER MI AND
NORTHERN IN ARE EXPECTED TO SPREAD WEST ACROSS NORTHERN IL LATER
THIS MORNING WITH UNCERTAINTY FOR TIMING. HAVE DELAYED THE MVFR
CIGS ARRIVAL WITH THIS FORECAST AND FURTHER TIMING REFINEMENTS
ARE LIKELY. THE MVFR CIGS ARE THEN EXPECTED TO LIFT FROM NORTH
TO SOUTH LATER THIS AFTERNOON INTO THIS EVENING.
EAST/NORTHEAST WINDS WILL CONTINUE THROUGH THE PERIOD WITH
SPEEDS AND GUSTS INCREASING THIS MORNING AND GUSTS INTO THE 20KT
RANGE POSSIBLE THROUGH SUNSET. SPEEDS/GUSTS WILL SLOWLY DIMINISH
THIS EVENING.
THERE REMAINS A VERY LOW CHANCE FOR SOME SPRINKLES OR AN
ISOLATED SHOWER TODAY. IF ANY WERE TO OCCUR, PERHAPS FAVORED
ACROSS NORTHWEST IN. CMS
LOT WATCHES/WARNINGS/ADVISORIES
IL...BEACH HAZARDS STATEMENT THROUGH THURSDAY MORNING FOR ILZ006.
BEACH HAZARDS STATEMENT THROUGH THIS EVENING FOR ILZ103-ILZ104.
IN...BEACH HAZARDS STATEMENT UNTIL 10 AM CDT THIS MORNING FOR
INZ001-INZ002.
LM...SMALL CRAFT ADVISORY UNTIL 10 PM CDT THIS EVENING FOR THE IL
NEARSHORE WATERS.
SMALL CRAFT ADVISORY UNTIL 10 AM CDT THIS MORNING FOR CALUMET
HARBOR IL TO BURNS HARBOR IN.
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