883
FXUS63 KIWX 211729
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
129 PM EDT WED OCT 21 2026
KEY MESSAGES
- DENSE FOG IS EXPECTED THIS MORNING, PARTICULARLY ALONG AND
EAST OF INTERSTATE 69. MORE PATCHY FOG IS POSSIBLE TONIGHT
WITH THE GREATEST CHANCES ACROSS NORTHEAST INDIANA AND
NORTHWEST OHIO. SOME LOCALLY DENSE FOG IS POSSIBLE AGAIN EARLY
THURSDAY MORNING.
- DRY WEATHER WILL CONTINUE THROUGH THE WEEKEND WITH
TEMPERATURES SLIGHTLY ABOVE NORMAL. TEMPERATURES ARE EXPECTED
TO COOL TO SLIGHTLY BELOW NORMAL BY NEXT TUESDAY AND
WEDNESDAY.
DISCUSSION
ISSUED AT 320 AM EDT WED OCT 21 2026
SATELLITE IMAGERY EARLY THIS MORNING DEPICTS AN EXPANSIVE AREA OF
STRATUS/FOG ACROSS NORTHWEST OHIO, WITH WIDESPREAD DENSE FOG
DEVELOPING ACROSS SOUTH CENTRAL LOWER MICHIGAN AND NORTHWEST OHIO.
WEAK EASTERLY FLOW ASSOCIATED WITH EASTERN PORTIONS OF LOW LEVEL
ANTICYCLONE WILL SUPPORT WESTWARD MIGRATION OF THIS STRATUS/FOG INTO
FAR NORTHEAST INDIANA OVER THE NEXT SEVERAL HOURS. A DENSE FOG
ADVISORY HAS ISSUED EARLIER THIS MORNING FOR HILLSDALE CO MI AND ALL
OF NW OHIO COUNTIES, AND BASED ON CURRENT TRENDS, A WESTWARD
EXPANSION WILL LIKELY BE REQUIRED. WITH EXPANSIVE LOW LEVEL
ANTICYCLONE IN PLACE AND VERY WEAK LOW LEVEL FLOW, DIURNAL
MIXING WILL LIKELY BE SLOW TO ERODE STRATUS/FOG, WITH AREAS OF
FOG PERSISTING THROUGH THE 14 TO 15Z TIMEFRAME.
OTHERWISE FOR TODAY WILL BE MONITORING THE PROGRESS OF A PROGRESSIVE
MID/UPPER LEVEL SHORT WAVE TROUGH ACROSS THE UPPER MIDWEST THIS
MORNING AS IT REACHES THE WESTERN GREAT LAKES REGION. A NARROW
AXIS OF MID LEVEL MOISTURE/PATCHY MID LEVEL CLOUDS WILL LIKELY
REMAIN NORTH OF THE LOCAL AREA WHILE ANOTHER AREA OF MID CLOUDS
ASSOCIATED WITH MID LEVEL SHORT WAVE PROGRESSING THROUGH MEAN
UPPER RIDGING WILL LARGELY REMAIN DISPLACED TO THE WEST FROM THE
CENTRAL PLAINS TO THE MID MS VALLEY. A PERSISTENCE FORECAST
LARGELY UTILIZED FOR HIGH TEMPERATURE FORECAST TODAY AS LITTLE
THERMAL ADVECTIONS HAVE BEEN NOTED OVER PAST 24 HOURS WITH
SIMILAR POOR MIXING PROFILES TODAY AND SIMILAR GOOD AMOUNTS OF
INSOLATION.
PASSAGE OF THE GREAT LAKES SHORT WAVE THIS EVENING WILL ALLOW FOR
REINFORCEMENT AND SOUTHWESTWARD SHIFT TO LOW LEVEL ANTICYCLONE
ACROSS THE REGION. THIS SHOULD YIELD A WEAK NORTHEASTERLY LOW LEVEL
FLOW PROFILE FOR TONIGHT WHICH ONCE AGAIN RAISES THE QUESTION OF
SOME ENHANCEMENT TO FOG DEVELOPMENT DOWNWIND OF EASTERN GREAT LAKES.
GIVEN NORTHEAST TRAJECTORIES, GREATEST CONFIDENCE IN FOG DEVELOPMENT
TONIGHT IS FAR NE IN/NW OH MAINLY ALONG AND SOUTH OF US ROUTE 24,
BUT SOME PATCHY FOG WILL BE POSSIBLE ONCE AGAIN FOR MANY AREAS EAST
OF I-69. THE FOG MAY BECOME LOCALLY DENSE ONCE AGAIN EARLY THURSDAY
MORNING.
A STABLE WAVE PATTERN WILL MAINTAIN THROUGH THE FIRST PART OF THE
WEEKEND WITH AN EVENTUAL SHIFT OF LONGWAVE UPPER RIDGE AXIS
EAST OF THE LOCAL AREA BY 2ND HALF OF THE WEEKEND. THIS SHOULD
ALLOW FOR SUNDAY TO REALIZE THE WARMEST TEMPERATURES OF THE
PERIOD IN THE LOW TO MID 70S. LONGWAVE PREDICTABILITY BEGINS TO
BREAK DOWN EARLY NEXT WEEK WITH LARGE DISCREPANCIES IN HOW
PHASING IS DEPICTED WITH WESTERN CONUS CLOSED UPPER HEIGHT
PERTURBATIONS AMONG VARIOUS DETERMINISTIC/ENSEMBLE GUIDANCE.
SOME INDICATIONS THAT STRONGER FRONTAL FORCING WILL DEVELOP
NORTHWEST OF THE LOCAL AREA LATE WEEKEND/EARLY NEXT WEEK AS
SOUTHWEST CONUS UPPER WAVE PUSHES EAST AND DAMPENS, BUT GIVEN
UNCERTAINTY IN PROGRESSION AND DEPTH OF THIS WAVE AS IT REACHES
CENTRAL CONUS ARGUES FOR MAINTENANCE OF MAINLY DRY FORECAST AT
THIS TIME WITH EXPECTATION THAT FRONTAL FORCING WILL WANE
THROUGH TIME. BLENDED GUIDANCE IDEA OF TREND BACK TO COOLER
CONDITIONS EARLY TO MID NEXT WEEK STILL APPEARS REASONABLE.
AVIATION /18Z TAFS THROUGH 18Z THURSDAY/
ISSUED AT 125 PM EDT WED OCT 21 2026
PRIMARY CHALLENGE, MUCH LIKE YESTERDAY, REVOLVES AROUND
FOG/STRATUS DEVELOPMENT AT KFWA OVERNIGHT. MODEL SIGNALS SEEM TO
KEEP THE WORST JUST SE OF KFWA, BUT A FEW INDICATIONS AT LEAST
SOME IMPACTS REMAINS. WILL CONTINUE WITH A PREDOMINATE MVFR VSBY
AT KFWA, WITH THE POTENTIAL FOR GREATER IMPACTS IN THE 9Z TO 14Z
WINDOW THAN CURRENTLY FORECASTED. ANY FOG/STRATUS SHOULD BURN
OFF BETWEEN 14 AND 16Z. KSBN SHOULD BE SPARED ANY IMPACTS AT
THIS POINT.
OTHERWISE NO FLIGHT CONCERNS OUTSIDE THIS WINDOW.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...NONE.
DISCUSSION...MARSILI
AVIATION...FISHER
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