265
FXUS63 KIWX 201146
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
746 AM EDT THU AUG 20 2026
KEY MESSAGES
- MOSTLY DRY TODAY WITH ONLY A SLIGHT CHANCE (20 PERCENT) FOR
ISOLATED SHOWERS AND STORMS IN THE LATE AFTERNOON AND EARLY
EVENING. SEVERE WEATHER IS NOT EXPECTED. HIGHS AROUND 80
DEGREES.
- THE NEXT CHANCE FOR SHOWERS AND STORMS WILL BE LATE FRIDAY
AFTERNOON INTO SUNDAY MORNING. THE BEST CHANCES (50-75
PERCENT) WILL BE SATURDAY AFTERNOON EAST OF INTERSTATE 69.
ELSEWHERE, EXPECT CLOSER TO 30-50 PERCENT CHANCE. SEVERE
WEATHER IS NOT EXPECTED.
- HAZARDOUS SWIMMING CONDITIONS ARE POSSIBLE FOR LAKE MI
BEACHES ALONG BERRIEN CO, MI AND LA PORTE COUNTY, IN THIS
WEEKEND. DANGEROUS WAVES AND CURRENTS ARE POSSIBLE. MONITOR
THE BEACH FORECAST FOR UPDATES.
DISCUSSION
ISSUED AT 518 AM EDT THU AUG 20 2026
MORNING RAIN SHOWERS SOUTH OF US 30 CONTINUE TO DEVELOP CLOSE TO THE
EXITING COLD FRONT/LOW PRESSURE SYSTEM, WITH LIGHT NORTHEAST WINDS
EAST OF I 69 IN MI/TOLEDO/FINDLAY AND A MORE NORTHERLY DIRECTION
WEST OF THERE. NEAR FORT WAYNE/WARSAW/DEFIANCE WINDS ARE CALM. THE
HEAVIEST RAIN SHOWERS/STORMS THAT DROVE THE FLOOD WATCH REMAINED
MOSTLY SOUTH OF OUR AREA OVERNIGHT, SO EVEN IF WE GET A FEW
HEAVIER/LINGERING SHOWERS THIS MORNING I DON'T ANTICIPATE MUCH IN
THE WAY OF FLOODING. CANCELLED THE FLOOD WATCH EARLY (PREV.
EXPIRATION AT 12Z). AS OF RIGHT NOW, SHOWERS EXTEND ALONG A LINE
FROM WABASH COUNTY, IN THROUGH HUNTINGTON/WELLS/ADAMS, AND THEN
INTO LIMA, OH (AND ITS DIMINISHING WITH TIME). THE HEAVIER AXIS
REMAINS JUST SOUTH OF VAN WERT/LIMA, OH (INTO ILN/CLE AREA),
WHERE THE SHOWERS HAVE BEEN TRAINING SINCE ABOUT 3 AM EDT.
I SUSPECT TODAY WILL END UP MOSTLY DRY OVERALL, WITH CHANCES
FOR RAIN FOCUSED THIS MORNING AND POSSIBLY AGAIN LATER THIS
AFTERNOON/EVENING. THE OVERALL TREND IN THE MID-UPPER LEVELS IS
DRYING THROUGH THE DAY, ESPECIALLY BEHIND THE INITIAL WAVE THIS
MORNING WHEN SUBSIDENCE TAKES OVER. IT APPEARS WE STILL RETAIN
OUR LOW LEVEL MOISTURE THROUGH THE EVENING. FLOW ALOFT BECOMES
FAIRLY ZONAL, AND SOME OF THE MODELS KICK A WEAK SHORTWAVE
THROUGH AROUND 00Z. ADDITIONALLY, WITH THE LIGHTER FLOW AT THE
SURFACE AND DAYTIME HEATING DEVELOPING, LAKE BREEZES MAY DEVELOP
DURING THE AFTERNOON AND MOVE INLAND. WINDS OUT OF THE EAST-
NORTHEAST OVER LAKE ERIE THIS AFTERNOON STRENGTHEN AS THE LOW
EXITS THE AREA AND MOVES INTO NY/PA. FLOW OFF LAKE MI DOES
STRENGTHEN AND AN INVERTED TROUGH-LIKE FEATURE FORMS NEAR I 69
EAST--WHICH COULD PROVIDE ADEQUATE MOISTURE CONVERGENCE FOR
SHOWER DEVELOPMENT AROUND 21-03Z. DEPENDING ON HOW THE CLOUD
COVER EVOLVES THIS MORNING INTO THE AFTERNOON, WE COULD END UP
SEEING AN ISOLATED STORM OR TWO. ML CAPE BY THIS AFTERNOON COULD
RANGE FROM 500-900 J/KG (SFC BASED 1500 J/KG) IF WE CAN GET
ENOUGH HEATING. FOR NOW, MAINTAINED A 20 PERCENT CHANCE FOR
SHOWERS AND STORMS STARTING AROUND 21Z AND CONTINUING THROUGH
3Z, MAINLY EAST OF IN 15. WITH WEAK FLOW OVERALL, THERE IS
LITTLE TO NO SHEAR TO WORK WITH SO DO NOT ANTICIPATE ANY SEVERE
WEATHER. THERE IS A LOT OF MODEL SPREAD THIS AFTERNOON/EVENING
REGARDING THIS SCENARIO--IT COULD BE THAT WE REMAIN COMPLETELY
DRY THROUGH FRIDAY AFTERNOON. THE MODELS THAT KEY IN ON THE
CONVERGENCE AND DEVELOP SHOWERS/STORMS KEEP THEM FAIRLY ISOLATED
(NOT WIDESPREAD).
MOSTLY DRY CONDITIONS PERSIST THROUGH MUCH OF FRIDAY, THEN IN THE
LATE AFTERNOON/EVENING HOURS A DEEPENING 500MB TROUGH BUILDS IN
ALOFT, AND A BROAD SURFACE LOW OVER NORTHERN ONTARIO DRIFTS TOWARDS
JAMES BAY. THIS WILL BRING A COLD FRONT THROUGH INTO SATURDAY. THE
SFC LOW DEEPENS AND DROPS SOUTH AS THE TROUGH BASE BUILDS IN FROM
THE WEST, CONSOLIDATING OVER SOUTHERN ONTARIO/LOWER GREAT LAKES BY
06Z SUNDAY. EXPECT WE'LL HAVE CHANCES (20-50 PERCENT) FOR RAIN
SHOWERS AND A FEW STORMS WITH THE COLD FRONT FRIDAY NIGHT INTO EARLY
SATURDAY FOR AREAS GENERALLY WEST OF I 69, THEN AS THE FRONT MOVES
EAST AND UPPER LEVEL FORCING STRENGTHENS DURING DAYTIME HEATING
SATURDAY AFTERNOON, CHANCES INCREASE TO MORE LIKE 50-75 PERCENT
(ESPECIALLY IN NW OH). THE SYSTEM THEN MOVES EASTWARD FROM THERE,
LEAVING OUR AREA ON THE BACK SIDE OF THE UPPER LEVEL TROUGH WITH
DECENT NORTHWEST FLOW THROUGH SUNDAY. SOME OF THE GUIDANCE GENERATES
SHOWERS FROM LAKE MI INLAND AS A SHORTWAVE PINWHEELS AROUND THE LOW
SATURDAY NIGHT INTO SUNDAY, BUT GUIDANCE IS CONFLICTED ON THAT. LEFT
SUNDAY DRY FOR NOW. WITH DECENT NORTH-NORTHWEST FLOW (15-25 MPH
WINDS) ON LAKE MI SATURDAY INTO SUNDAY, WAVES ARE LIKELY TO BUILD UP
TO 3-5 FEET. WE'LL AT LEAST NEED A MODERATE SWIM RISK DURING THESE
TWO DAYS FOR BEACHES ALONG BOTH THE BERRIEN CO, MI/LA PORTE CO, IN
SHORELINE. I THINK WE'LL PROBABLY SEE HIGH SWIM RISK CONDITIONS
DEVELOP BOTH DAYS, ESPECIALLY DURING THE AFTERNOON/EVENING. A BEACH
HAZARDS STATEMENT WILL LIKELY BE NEEDED DEPENDING ON HOW THE WIND
FORECAST EVOLVES IN THE NEXT COUPLE DAYS.
MONDAY INTO TUESDAY NIGHT OUR CWA RESTS ON THE BORDER BETWEEN THE
EXITING UPPER LEVEL LOW (MOVED OFF TO QUEBEC/NE CONUS) AND A BROAD
HIGH PRESSURE RIDGE EXTENDING FROM THE DESERT SOUTHWEST. WE'LL BE ON
THE NORTHEASTERN PERIPHERY, WHICH SHOULD KEEP US MOSTLY DRY. THERE
ARE A FEW WEAK SHORTWAVES THAT MOVE THROUGH ON THE EDGE OF THIS
RIDGE, BUT CONFIDENCE WASN'T HIGH ENOUGH TO INCLUDE ANY PRECIP
CHANCES AT THIS TIME (MOST OF THE GUIDANCE REMAINS DRY).
TUESDAY NIGHT INTO THURSDAY, ANOTHER TROUGH/UPPER LOW BEGINS TO
BREAK DOWN THE RIDGE, AND A SURFACE COLD FRONT MOVES THROUGH.
GUIDANCE ON THE UPPER LEVEL PATTERN IS CONFLICTED AT THIS POINT, SO
KEY SURFACE FEATURES LIKE THE FRONT MAY BE MISPLACED-BUT I
MAINTAINED THE BROADBRUSH 20-30 PERCENT CHANCES FOR SHOWERS/STORMS
ON THESE DAYS.
TEMPERATURES THROUGH NEXT THURSDAY WILL LARGELY BE IN THE MID-UPPER
70S, LOW 80S. THE EXCEPTION WOULD BE SUN/MON WHEN WE DO SEE SEVERAL
LOCATIONS IN THE LOW-MID 70S. LOWS WILL BE IN THE MID-UPPER 50S-
LOW 60S, EXCEPT FOR SUNDAY NIGHT WHERE WE SEE VALUES IN THE LOW
50S.
AVIATION /12Z TAFS THROUGH 12Z FRIDAY/
ISSUED AT 741 AM EDT THU AUG 20 2026
PREDOMINANTLY VFR AT KSBN THROUGH THE PERIOD. AT KFWA,
PREDOMINANTLY MVFR/IFR CONDITIONS THROUGH THE FIRST PORTION OF
THE DAY, BECOMING VFR LATER THIS AFTERNOON. RIGHT NOW WE HAVE
SOME BR (3-4SM) AT THE TERMINAL AND SURROUNDING SITES, WITH
CEILINGS BOUNCING BETWEEN 1500-2500 FEET. EXPECT THIS TO
CONTINUE ON AND OFF THROUGH THE MORNING. STILL POTENTIAL FOR
ISOLATED SHOWERS AND MAYBE A T-STORM LATE THIS AFTERNOON/EVENING
AT KFWA, BUT CONFIDENCE IS LOW. LEFT AS A PROB30 GROUP FOR NOW.
OTHERWISE, BR DEVELOPMENT LATE TONIGHT, POSSIBLE AT KSBN BUT
MOST LIKELY AT KFWA. FOR NOW WENT MVFR WITH VISIBILITIES, THOUGH
GUIDANCE SUGGESTS WE COULD SEE VALUES AROUND 1-2SM AT TIMES.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...NONE.
DISCUSSION...MCD
AVIATION...MCD
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