093
FXUS63 KIWX 221011
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
611 AM EDT THU OCT 22 2026
KEY MESSAGES
- PATCHY FOG IS EXPECTED TO CONTINUE DEVELOP THIS MORNING,
ESPECIALLY SOUTH OF US ROUTE 24 ACROSS NORTHEAST INDIANA AND
NORTHWEST OHIO. THE PATCHY FOG MAY BE LOCALLY DENSE. FOG MAY
BECOME MORE WIDESPREAD THURSDAY NIGHT INTO EARLY FRIDAY
MORNING ACROSS NORTHWEST OHIO.
- DRY WEATHER AND ABOVE NORMAL TEMPERATURES ARE EXPECTED THROUGH THE
WEEKEND.
DISCUSSION
ISSUED AT 330 AM EDT THU OCT 22 2026
A SHORT WAVE TROUGH CONTINUES TO DIVE SOUTHEAST ACROSS SOUTHEAST
ONTARIO THIS MORNING. LOW LEVEL RIDGING IS BEING REINFORCED BEHIND
THIS SHORT WAVE ACROSS THE MID MS RIVER VALLEY, AND THIS WILL
PROLONG THE PERIOD OF WEAK GRADIENT THAT HAS BEEN IN PLACE LOCALLY
THE PAST SEVERAL DAYS. IDEAL RADIATIONAL COOLING CONDITIONS THIS
MORNING WILL CONTINUE TO SUPPORT SOME PATCHY FOG POTENTIAL, AND
PRESENT INDICATIONS STILL SUGGEST THAT SOUTHEAST PORTIONS OF THE
AREA DOWNWIND OF EASTERN GREAT LAKES MAY EXPERIENCE A BRIEF PERIOD
OF GREATER FOG COVERAGE THIS MORNING SOUTH OF US ROUTE 24 ACROSS
NORTHEAST INDIANA AND NORTHWEST OHIO. OTHERWISE FOR TODAY LARGE
SCALE FLOW AMPLIFICATION IS EXPECTED AS A STRONGER UPPER VORT LOBE
ACROSS SOUTHEAST CANADA PHASES WITH AN ATLANTIC VORT MAX. MEANWHILE,
A CUT-OFF UPPER LOW WILL CONTINUE TO MIGRATE SLOWLY EASTWARD INTO
SOUTHERN CALIFORNIA THIS EVENING. THIS EVOLUTION WILL RESULT AN
AMPLIFYING LOW/UPPER LEVEL RIDGING ACROSS CENTRAL CONUS AND SOUTH
CENTRAL CANADA. LOW LEVEL/NEAR SFC WINDS WILL VEER MORE EASTERLY AS
THIS AMPLIFICATION OCCURS WHICH WILL RESULT IN CONTINUED WEAK
THERMAL ADVECTIONS OVER THE NEXT 24 HOURS. THUS, A PERSISTENCE
FORECAST HAS BEEN UTILIZED ONCE AGAIN TODAY IN TERMS OF MAX
TEMPS. THE VEERING LOW LEVEL FLOW MAY ALLOW SOME SLIGHTLY BETTER
LOW LEVEL MOISTURE TO DROP SOUTH INTO THE AREA FROM THE GREAT
LAKES, BUT THE ONLY POSSIBLE EFFECT FROM THIS WEAK ADVECTION
WOULD BE SOME VERY LOW COVERAGE DIURNAL CU THAT WILL NOT HAVE
ANY IMPACT ON TEMPS TODAY.
THIS TRANSITION BACK TO LOW LEVEL EASTERLIES WILL LIKELY SUPPORT
ADDITIONAL STRATUS/FOG DEVELOPMENT DOWNWIND OF THE EASTERN GREAT
LAKES TONIGHT, WITH A POTENTIAL OF SOME DENSE FOG EARLY FRIDAY
MORNING ACROSS NORTHWEST OHIO, SOUTH CENTRAL MICHIGAN, AND
POSSIBLY INTO PORTIONS OF NORTHEAST INDIANA. LOW TEMPERATURES
TONIGHT WILL DROP BACK INTO THE LOW 40S ONCE AGAIN, BUT MAY DIP
INTO UPPER 30S FOR FAVORED, COOL LOW-LYING SPOTS.
GUIDANCE IS STARTING TO COME INTO A BIT BETTER AGREEMENT
REGARDING LARGE SCALE FLOW THROUGH THE WEEKEND. A STRONGER AND
MORE PROGRESSIVE NORTHERN STREAM UPPER LEVEL SYSTEM WILL SHIFT
ACROSS SOUTH CENTRAL CANADA THIS WEEKEND WHICH WILL DRIVE A COLD
FRONT BOUNDARY SOUTHWARD ACROSS THE GREAT LAKES. TRACK OF THIS
NORTHERN STREAM WAVE IS EXPECTED TO REMAIN WELL TO THE NORTH,
AND DEPARTURE OF THIS WAVE WILL LIKELY HANG UP THE FRONT NORTH
OF THE LOCAL AREA THROUGH THE WEEKEND. WITH FORCING/FRONTAL
POSITION TO THE NORTH, AND NARROW ZONE OF BETTER PRE-FRONTAL
MOISTURE TRANSPORT REMAINING FROM THE CENTRAL PLAINS TO THE
NORTHERN GREAT LAKES, A DRY FORECAST REMAINS INTACT THROUGH
MONDAY. THE WARMEST DAYS OF THIS FORECAST PERIOD STILL LOOK TO
BE SUNDAY/MONDAY AS VEERED LOW LEVEL FLOW ALLOWS FOR SOME MODEST
INCREASE IN LOW LEVEL WARM ADVECTION.
BY TUESDAY/WEDNESDAY THE SOUTHERN STREAM CUT-OFF LOW IS EXPECTED TO
EJECT EAST AND DAMPEN. THIS WAVE COULD INTERACT WITH THE STALLED
FRONTAL BOUNDARY ACROSS THE UPPER MS VALLEY TO THE GREAT LAKES WITH
SOME WEAK ISENTROPIC ASCENT POSSIBLE. GIVEN DAMPENING NATURE OF THIS
WAVE AND LIKELY MARGINAL MOISTURE PROFILES, BLENDED POPS REMAIN ONLY
IN THE 10 TO 20 PERCENT RANGE TOWARD THE END OF THIS FORECAST VALID
PERIOD.
AVIATION /12Z TAFS THROUGH 12Z FRIDAY/
ISSUED AT 610 AM EDT THU OCT 22 2026
FOG WILL CONTINUE TO BE THE PRIMARY FORECAST CONCERN THROUGH THE
PERIOD. A WEST-SOUTHWEST MIGRATION OF LOW LEVEL RIDGE AXIS HAS
FAVORED A WEAK NORTHERLY NEAR SFC FLOW COMPONENT THIS MORNING.
THIS HAS KEPT THE BULK OF SIGNIFICANT FOG FORMATION ACROSS
NORTHWEST OHIO DUE TO LAKE ERIE INFLUENCE. CANNOT COMPLETELY
RULE OUT SOME BRIEF IFR VSBYS IN PATCHY FOG EARLY THIS MORNING,
BUT VERTICAL MOISTURE PROFILES SEEMS TO BE MORE SUPPORTIVE OF
THESE LOWER VSBYS IN NW OHIO. OTHERWISE, ANOTHER QUIET DAY IN
STORE WITH MINIMAL AVIATION WEATHER CONCERNS AS VFR CONDITIONS
AND LIGHT WINDS ARE EXPECTED AFTER ANY PATCHY FOG DISSIPATES BY
14Z. THE AMPLITUDE OF THE LOW LEVEL RIDGING WILL INCREASE LATER
TODAY INTO TONIGHT, EVENTUALLY SETTING UP MORE OF AN EASTERLY
NEAR SFC FLOW COMPONENT FOR TONIGHT INTO EARLY FRIDAY MORNING.
THIS MAY BE MORE SUPPORTIVE OF GREATER COVERAGE FOG FOR EARLY
FRIDAY MORNING, BUT EARLY INDICATIONS WOULD SUGGEST GREATER RISK
JUST EAST OF KFWA AND INTO NW OHIO.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...NONE.
DISCUSSION...MARSILI
AVIATION...MARSILI
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