786
FXUS63 KLOT 241746
AFDLOT
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE, IL
1246 PM CDT THU SEP 24 2026
KEY MESSAGES
- BELOW AVERAGE TEMPERATURES EXPECTED THROUGH THE WEEKEND BEFORE
TEMPERATURES TURN MORE SEASONABLE EARLY NEXT WEEK.
- NO SIGNIFICANT WIDESPREAD PRECIPITATION CHANCES ARE EXPECTED
AT THIS TIME UNTIL THE MIDDLE OF NEXT WEEK.
DISCUSSION
ISSUED AT 220 AM CDT THU SEP 24 2026
FORECAST AREA REMAINS ON THE NORTHWESTERN PERIPHERY OF AN
UPPER-LEVEL LOW WHICH IS PROGGED TO DEEPEN ACROSS THE MID-
ATLANTIC REGION OVER THE NEXT COUPLE OF DAYS. GOES WATER VAPOR
IMAGERY CURRENTLY INDICATES A SMALLER-AMPLITUDE SHORT WAVE
WRAPPING WEST-SOUTHWEST ACROSS LOWER MI/LM AND IN AROUND THE
BACK SIDE OF THIS SYSTEM. THE MAIN IMPACT OF THIS DISTURBANCE ON
OUR FORECAST AREA IS TO CONTINUE TO SPREAD AN EXPANSIVE AREA OF
LOW CLOUDS TO THE WEST ACROSS THE CWA EARLY THIS MORNING
(THOUGH SOME LARGE BREAKS HAVE DEVELOPED TOWARD THE IL/WI
BORDER), WITH SOME PATCHY DRIZZLE REPORTED EARLIER SOUTH OF THE
I-80 CORRIDOR INTO CENTRAL IL WHICH SHOULD END WITH THE PASSAGE
OF THE DISTURBANCE THIS MORNING. MOSTLY CLOUDY SKIES ARE
EXPECTED TODAY ESPECIALLY FOR OUR SOUTH/SOUTHEASTERN CWA. WHILE
SOME SIGNIFICANT BREAKS ARE LIKELY FARTHER NORTH, INCREASING
HIGH CLOUDS ARE EXPECTED LATER THIS AFTERNOON AS ANOTHER SHORT
WAVE TRACKS INTO THE UPPER MIDWEST FROM THE NORTHERN PLAINS.
OTHERWISE, LESS-BREEZY CONDITIONS ARE EXPECTED TODAY WITH HIGH
TEMPS IN THE UPPER 60S TO LOWER 70S (MID-60S ALONG THE LAKE
MICHIGAN SHORE).
VARIOUS MODEL GUIDANCE INDICATES THE POTENTIAL FOR SOME SPOTTY
SHOWERS TO SPREAD INTO FAR NORTH/NORTHWEST IL TOWARD DAYBREAK
FRIDAY, IN ASSOCIATION WITH THE AFOREMENTIONED SHORT WAVE
PROPAGATING INTO THE UPPER MIDWEST. THIS WAVE WILL BE RUNNING
INTO SHORT WAVE RIDGING ALOFT ON THE NORTHWESTERN FRINGE OF THE
DEEPENING EAST COAST LOW HOWEVER, WHICH ALONG WITH EASTERLY
LOW-LEVEL DRY AIR ADVECTION IS EXPECTED TO LIMIT THE EASTWARD
DEVELOPMENT OF PRECIPITATION. HAVE INCLUDED SOME SLIGHT CHANCE
(<=20%) POPS FOR THESE DECAYING SHOWERS MAINLY WEST OF THE FOX
RIVER VALLEY ACROSS NORTHERN AND NORTHWEST IL BETWEEN ABOUT
4AM-10AM FRIDAY MORNING.
BEHIND FRIDAY'S WAVE, THE NARROW UPPER-LEVEL RIDGE IS THEN
PROGGED TO BRIEFLY REDEVELOP INTO THE UPPER-MIDWEST FRIDAY NIGHT
INTO SATURDAY BEFORE ANOTHER SHORT WAVE APPROACHES THE UPPER-
MIDWEST SATURDAY EVENING. SIMILAR TO FRIDAY MORNING'S SCENARIO,
THIS WAVE WILL ALSO BE FIGHTING THE RIDGE AND DRY EASTERLY LOW-
LEVEL FLOW. SOME DECAYING SHOWERS WILL AGAIN BE POSSIBLE
SATURDAY NIGHT ACROSS OUR FAR WESTERN COUNTIES OF THE FORECAST
AREA, WHERE AGAIN SOME SLIGHT CHANCE (<20%) POPS ARE IN PLACE
WEST OF I-39. DAYTIME HOURS LOOK TO BE DRY OVER THE WEEKEND,
THOUGH DUE TO THE BLOCKING OF THE PATTERN OF THE DEEP EAST COAST
UPPER LOW, OUR ANTICIPATED GRADUAL WARMING TREND LOOKS TO BE ON
HOLD. PARTLY TO MOSTLY CLOUDY SKIES AND CONTINUED MODEST EAST-
NORTHEAST SURFACE WINDS WILL LIKELY KEEP OUR TEMPERATURES
SLIGHTLY BELOW AVERAGE IN THE MID-60S TO LOWER 70S BOTH
SATURDAY AND SUNDAY.
A SLOWER EVOLUTION IS NOT UNUSUAL IN SUCH HIGHLY-AMPLIFIED
UPPER AIR PATTERNS, AND THE LATEST GLOBAL MODEL/ENSEMBLE
SOLUTIONS HAVE DELAYED KICKING OUT THE EASTERN LOW UNTIL EARLY-
MID NEXT WEEK. AS THIS OCCURS, THERE ARE INDICATIONS THAT THE
PATTERN WILL BECOME MORE ACTIVE WITH AN EASTWARD-MOVING FRONTAL
ZONE AND SURFACE LOW DEVELOPING INTO THE REGION TOWARD MID-
WEEK. NBM INITIALIZATION DEPICTS THIS WITH 40-60% POPS LATER
TUESDAY INTO WEDNESDAY AND MADE NO CHANGES AT THIS DISTANCE,
THOUGH THERE IS QUITE A BIT OF ENSEMBLE SPREAD IN THE CURRENT
00Z EPS/GEFS/CMCE SOLUTIONS WITH THE TIMING/STRENGTH AND
PLACEMENT OF FEATURES AT THIS TIME.
RATZER
AVIATION /18Z TAFS THROUGH 00Z SATURDAY/
ISSUED AT 1246 PM CDT THU SEP 24 2026
THERE ARE NO MAJOR AVIATION WEATHER CONCERNS ANTICIPATED
THROUGH THE PERIOD.
SURFACE HIGH PRESSURE IS EXPECTED TO REMAIN LOCKED IN ACROSS THE
GREAT LAKES REGION THROUGH THE WEEKEND. THIS WILL RESULT IN
EASTERLY SURFACE WINDS TILL FURTHER NOTICE. OTHERWISE,
OCCASIONAL CIGS (MAINLY VFR) ARE EXPECTED THROUGH FRIDAY. ALSO
CANNOT RULE OUT A FEW NON-IMPACTFUL SPRINKLES FRIDAY MORNING.
KJB
LOT WATCHES/WARNINGS/ADVISORIES
IL...NONE.
IN...NONE.
LM...NONE.
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