266
FXUS63 KIWX 130008
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
808 PM EDT SUN OCT 12 2025
KEY MESSAGES
- AREAS OF FOG EXPECTED TO DEVELOP OVERNIGHT, PARTICULARLY FAR
NORTHEAST INDIANA, SOUTH CENTRAL LOWER MICHIGAN, AND FAR
NORTHWEST OHIO. SOME LOCALLY DENSE FOG IS POSSIBLE.
- NEAR TO SLIGHTLY ABOVE NORMAL TEMPERATURES EXPECTED THIS
WEEK, WITH MONDAY AND TUESDAY THE WARMEST DAYS.
- CHANCES (30-50%) FOR RAIN NEXT WEEKEND.
UPDATE
ISSUED AT 800 PM EDT SUN OCT 12 2025
FOG POTENTIAL REMAINS THE PRIMARY FORECAST CONCERN OVERNIGHT.
LOW LEVEL MIXING EARLIER THIS AFTERNOON ALLOWED SFC DEW POINTS
TO MIX OUT FROM THE MID 40S TO AROUND 50. THIS WOULD SUGGEST A
SOMEWHAT LIMITED FOG POTENTIAL GIVEN FAIRLY LOW CROSSOVER TEMPS,
BUT LOW LEVEL EASTERLY FLOW IS ADVECTING HIGHER SFC DEW POINTS
WESTWARD FROM THE EASTERN GREAT LAKES THIS EVENING. DECENT
RADIATIONAL COOLING CONDITIONS AND THIS INFLUX OF HIGHER NEAR
SFC DEW POINTS SHOULD BE CONDUCIVE FOR FOG FORMATION TONIGHT,
PARTICULARLY NORTHEAST INDIANA, FAR NORTHWEST OHIO, AND SOUTH
CENTRAL LOWER MICHIGAN. ONE LIMITING FACTOR FOR WIDESPREAD
SIGNIFICANT FOG COULD BE SOME LIMITED WIND SHEAR IN NEAR SFC
LAYER THAT COULD PROMOTE A FOG/STRATUS COMBINATION. HOWEVER,
COULD SEE A SCENARIO LIKE YESTERDAY WHERE DRY SOILS/GROUND
CONDITIONS ALLOW POCKETS OF STRONGER RADIATIONAL COOLING THAT
WILL BE MORE CONDUCIVE FOR WIDESPREAD FOG. NO MAJOR CHANGES MADE
TO PREVIOUS FORECAST, AND DID INCLUDE MENTION OF SOME DENSE FOG
POTENTIAL IN EARLY EVENING HWO UPDATE FOR THE AFOREMENTIONED
LOCATIONS.
DISCUSSION
ISSUED AT 233 PM EDT SUN OCT 12 2025
OUR OVERALL QUIET WEATHER PATTERN WILL PERSIST INTO THIS WEEK WITH
CENTRAL CONUS UPPER RIDGING REMAINING THE DOMINANT FEATURE.
EASTERLY NEAR SURFACE FLOW BROUGHT SOME MARINE LAYER FOG/STRATUS
INTO OUR MI AND FAR NW OH COUNTIES EARLIER THIS MORNING, WITH
PATCHY/SHALLOW FOG ELSEWHERE. A SIMILAR SETUP IS EXPECTED
TONIGHT WITH LIGHT WINDS, CLEAR SKIES AND TEMPS BOTTOMING OUT
NEAR XOVER VALUES. OPTED TO ADD IN SOME PATCHY FOG AS A RESULT,
BEST CHANCES NEAR THE MICHIGAN BORDER.
RENEWED TROUGHING INTO THE EASTERN GREAT LAKES AND NORTHEAST US
SENDS A WEAK COLD FRONT THROUGH THE AREA LATER TUESDAY INTO TUESDAY
NIGHT. SOME SUBTLE MID LEVEL FGEN ATTEMPTS TO CLIP THE AREA TUESDAY
NIGHT UNDER A 120 KT UPPER JET DIVING THROUGH THE GREAT LAKES. LOW
LEVELS WILL REMAIN DRY HOWEVER WITH THE MAIN IMPACT BEING A PERIOD
OF MID LEVEL CLOUD COVER AND COOLER (NEAR NORMAL) POST-FRONTAL TEMPS
INTO WEDNESDAY AND THURSDAY.
MODEL GUIDANCE CONTINUES TO BREAK DOWN UPPER RIDGING FRIDAY INTO
NEXT WEEKEND WITH SEVERAL SHORTWAVES AND A BROAD MOISTURE PLUME
TAKING AIM ON THE REGION. THIS BRINGS NEEDED CHANCES FOR
SHOWERS AND EMBEDDED STORMS BY THIS WEEKEND, THOUGH DETAILS
REGARDING THE AMPLITUDE AND ORIENTATION OF THE MAIN WAVE AND
ATTENDANT SFC REFLECTION REMAINS UNCERTAIN WITH NO CHANGES TO
NBM BROADBRUSH CHANCE POPS (30-50%).
AVIATION /00Z TAFS THROUGH 00Z TUESDAY/
ISSUED AT 800 PM EDT SUN OCT 12 2025
FOG POTENTIAL WILL CONTINUE TO BE THE MAIN AVIATION WEATHER
ISSUE TO RESOLVE FOR THIS FORECAST. SOME HIGHER NEAR SFC
MOISTURE IS BEING ADVECTED WESTWARD THIS EVENING FROM THE
EASTERN GREAT LAKES. THIS HIGHER NEAR SFC MOISTURE COMBINED WITH
DECENT RADIATIONAL COOLING CONDITIONS SHOULD PROMOTE FOG
DEVELOPMENT OVERNIGHT INTO EARLY MONDAY MORNING. THE GREATEST
POTENTIAL OF THIS FOG WILL LIKELY FOLLOW THE ZONE OF HIGHER SFC
DEW POINTS MENTIONED ABOVE, MAINLY ACROSS FAR NE INDIANA INTO
SOUTH CENTRAL LOWER MICHIGAN AND EXTREME NORTHWEST OHIO. FLOW
IN THE LOWEST 500 FEET MAY ALSO BE JUST STRONG ENOUGH TO SUPPORT
SOME COMBO OF FOG/STRATUS POTENTIAL. WITH TERMINALS EXPECTED TO
BE ON THE MARGINS OF THE MOST FAVORED AREAS OF FOG DEVELOPMENT,
WILL LIMIT MENTION TO TEMPO MVFR VSBYS DUE TO LOW CONFIDENCE,
BUT THE POTENTIAL DOES EXIST FOR LOWER VSBYS/CIGS. ANY FOG
SHOULD MIX OUT IN THE 13Z-14Z TIMEFRAME WITH VFR CONDITIONS FOR
THE REMAINDER OF THE PERIOD, AND A CONTINUATION OF LIGHT EAST-
SOUTHEAST FLOW.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...NONE.
UPDATE...MARSILI
DISCUSSION...STEINWEDEL
AVIATION...MARSILI
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