698
FXUS63 KIWX 130600
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
200 AM EDT MON OCT 13 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 /06Z TAFS THROUGH 06Z TUESDAY/
ISSUED AT 141 AM EDT MON OCT 13 2025
PREDOMINANTLY VFR CONDITIONS FOR BOTH TERMINALS THROUGH THE
PERIOD, WITH THE EXCEPTION OF POTENTIAL FOG/STRATUS DEVELOPMENT
CAUSING MVFR/IFR CONDITIONS (POTENTIALLY LOWER AT KFWA) LATE
TONIGHT INTO EARLY MONDAY MORNING. LIGHT E-SE FLOW WILL PERSIST
THROUGH MONDAY, WITH PERIODS OF NEARLY CALM/LIGHT AND VARIABLE
WINDS (ESPECIALLY EARLY THIS MORNING AND THEN AGAIN THIS EVENING
INTO THE OVERNIGHT). PERSISTED WITH THE PREVIOUS FORECAST RE:
FOG AS IT APPEARS TO BE ON TRACK BASED ON THE LATEST GUIDANCE
AND CURRENT OBSERVATIONS. MAINTAINED THE 4SM BR AT KSBN GIVEN
LOWER CONFIDENCE--IT'S POSSIBLE HIGH CLOUDS (10K-25K) TO THE
WEST BUILD IN TOWARDS DAYBREAK AND LIMIT RADIATIONAL COOLING
(SOME GUIDANCE ONLY DROPS TO 6SM).
THE MAIN CHANGE THIS ISSUANCE WAS TO LOWER KFWA FROM AN MVFR
TEMPO DOWN TO IFR BETWEEN 10-13Z. AS THE PREVIOUS DISCUSSION
MENTIONED, LIGHT FLOW OFF THE LOWER LAKES IS ADVECTING HIGHER
SURFACE DEWPOINTS FURTHER WESTWARD. AT THE MOMENT, KUSE (FULTON,
OH) AND THE TOLEDO AREA ARE REPORTING VISIBILITIES BETWEEN
1/4SM AND 2SM. FURTHER NORTH NEAR DETROIT, ANN ARBOR HAS BEEN
REPORTING 1/4SM TO 3SM THROUGH THE EVENING. SKIES WILL REMAIN
MOSTLY CLEAR OUTSIDE OF A FEW CLOUDS AROUND 25KFT (IT'S UNCLEAR
HOW FAR EASTWARD THE CLOUDS OVER WESTERN IL WILL MAKE IT),
CREATING OPTIMAL CONDITIONS FOR RADIATIONAL COOLING. FOR NOW THE
TEMPO HAS 3SM BETWEEN 10-13Z, HOWEVER ITS VERY POSSIBLE WE DROP
TO LIFR/VLIFR CONDITIONS (EITHER WITH VERY LOW STRATUS OR
VISIBILITIES). GUIDANCE SUGGESTS BETWEEN 2-4SM, EXCEPT THE NAM
WHICH SUGGESTS 1/4 TO 1/2SM BETWEEN 11-13Z WITH POTENTIAL FOR
BKN003. AT THE MOMENT MOST OF THE SURROUNDING SITES ARE 10SM,
WITH THE EXCEPTION OF KGWB (2 1/2 SM) AND KC62/KDFI (5SM). WILL
MONITOR TRENDS AND AMEND IF THE LOWER VISIBILITIES/CEILINGS
BECOME MORE WIDESPREAD AND LOOK TO IMPACT THE TERMINAL.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...NONE.
UPDATE...MARSILI
DISCUSSION...STEINWEDEL
AVIATION...MCD
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