416
FXUS63 KIWX 121159
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
759 AM EDT SAT SEP 12 2026
KEY MESSAGES
- THERE ARE CHANCES FOR RAIN SHOWERS (20-60%) AND THUNDERSTORMS
(20-30%) TODAY, MAINLY ALONG AND SOUTH OF US 24. SEVERE
WEATHER IS NOT EXPECTED. HIGHS WILL BE IN THE 80S.
- CHANCES FOR RAIN AND STORMS (20-40%) SUNDAY AFTERNOON AND
EVENING, THEN BETTER CHANCES (30-60%) TUESDAY INTO THURSDAY.
SEVERE WEATHER IS NOT EXPECTED AT THIS TIME. COOLER SUNDAY AND
MONDAY, WITH HIGHS IN THE 70S AND LOW 80S. WARMER AND HUMID
BY THE MIDDLE OF NEXT WEEK.
- HAZARDOUS SWIMMING CONDITIONS ARE EXPECTED FOR SOUTHEAST LAKE
MI BEACHES SUNDAY AND THEN AGAIN ON TUESDAY. BREAKING WAVES
AND CURRENTS ARE EXPECTED. SEE THE LATEST BEACH FORECAST FOR
DETAILS.
DISCUSSION
ISSUED AT 552 AM EDT SAT SEP 12 2026
A WARM FRONT NEAR INDY AS OF THIS WRITING WILL CONTINUE TO LIFT
NORTHEASTWARD THROUGH THE DAY, REACHING OUR AREA LATER THIS MORNING
AROUND 12-15Z, THEN HEADING INTO SOUTHERN ONTARIO/LAKE ERIE BY
AROUND 18Z. WARM AIR/MOISTURE ADVECTION IS FORCING AN AREA OF RAIN
AND THUNDERSTORMS NEAR THE FRONT, AND THIS WILL LIFT INTO OUR AREA
FOR THE MORNING. WAS INITIALLY SUSPICIOUS THE THUNDER WOULD NOT MAKE
IT HERE, BUT AS OF 9Z IT LOOKS FAIRLY HEALTHY THANKS TO SOME
ELEVATED INSTABILITY. AS THE WARM FRONT MOVES NORTH, MOISTURE
TRANSPORT TAKES ON A MORE EAST-NORTHEASTERLY TRACK-SO HAVE THE BEST
CHANCES ALONG AND SOUTH OF US 24 (BEST EAST OF I 69) THROUGH THE
MORNING/EARLY AFTERNOON. MEANWHILE, AN UPPER LEVEL TROUGH/SHORTWAVE
AND SURFACE COLD FRONT APPROACHES FROM THE WEST. AS OF THIS WRITING,
THE BOUNDARY EXTENDS SOUTHWARD FROM WESTERN LAKE SUPERIOR INTO WEST-
CENTRAL WI/EASTERN MN AND IA/IL. MODELS DON'T SEEM TO HAVE A GREAT
HANDLE ON THE PRECIPITATION ASSOCIATED WITH THIS FEATURE (MANY ARE
DRY AT THIS TIME IN THE LATEST RUNS). ITS FAIRLY LIGHT, BUT THERE
ARE A COUPLE THUNDERSTORMS NEAR THE IL/WI LINE. THE ACTUAL UPPER
LEVEL TROUGH AND SURFACE FRONT LOOK TO REACH OUR WESTERN CWA BORDER
BY 00Z (RIGHT ALONG LAKE MI SHORE, EXTENDING FROM IL INTO NORTHERN
ONTARIO). SOME OF THE MODELS INDICATE A PRE-FRONTAL TROUGH POSSIBLY
DEVELOPING TOWARDS THE AFTERNOON, WHICH COULD RE-INVIGORATE THE
ALREADY MOISTENED ATMOSPHERE IN AREAS MAINLY ALONG/SOUTH OF US 24. I
SUSPECT AS THE BETTER MOISTURE TRANSPORT GRADUALLY DIMINISHES AND
SHIFTS MORE E-NE OUT OF OUR AREA LATE THIS MORNING THAT WE'LL SEE A
DIMINISHING TREND TO THE PRECIPITATION ALONG THE INCOMING COLD FRONT
(THUS KEEPING AREAS FURTHER NORTH AND WEST OF US 24 DRY WITH
VARIABLE CLOUD COVER). IN THE AFTERNOON, THE SHORTWAVE/PRE-FRONTAL
TROUGH IS LIKELY TO TRIP AN INCREASE IN SHOWER/STORM ACTIVITY AGAIN,
ESPECIALLY AS IT ARRIVES AT A TIME OF DECENT HEATING (SFC CAPE
POTENTIALLY UP TO 1500 J/KG). LUCKILY WE DON'T HAVE MUCH IN THE WAY
OF ANY SHEAR OR STEEP MID LEVEL LAPSE RATES, SO NOT EXPECTING ANY
SEVERE WEATHER AT THIS TIME.
OTHERWISE, HEATING UP INTO THE MID-UPPER 80S FOR MANY LOCATIONS
TODAY (ESPECIALLY FURTHER NORTHWEST WHERE CLOUD COVER IS LOWER/NO
PRECIPITATION). EXPECT DRY CONDITIONS TONIGHT AS THE COLD FRONT
MOVES THROUGH, WITH WINDS SHIFTING WEST-NORTHWEST. WHILE WINDS
OVERNIGHT ARE LOWER INITIALLY, THEY INCREASE OUT OF THE N-NW SUNDAY
MORNING INTO THE AFTERNOON, ESPECIALLY NEAR LAKE MI AND ALONG/NORTH
OF THE TOLL ROAD. IF WINDS ON LAKE MI INCREASE TO 15KTS SUSTAINED
AND GUST TO AROUND 20-25 KNOTS...WE COULD END UP SEEING WAVES OF 3-5
FEET ON LAKE MI. HOWEVER, THE PAST FEW RUNS OF MODELS HAVE FLIP
FLOPPED ON THE INTENSITY OF THESE WINDS (INITIALLY LIGHTER WITH 2-3
FT WAVES). OPTED TO HOLD OFF ON THE BEACH HAZARDS STATEMENT THIS
ISSUANCE, BUT DID MAINTAIN A HIGH SWIM RISK FORECAST FOR BOTH LA
PORTE/BERRIEN COUNTY BEACHES. IF STRONGER WINDS VERIFY, WAVES SHOULD
REACH 3-5 FEET FAIRLY QUICKLY, APPROACHING AT ANGLES OF 45 TO 90
DEGREES RELATIVE TO SHORE WITH 6-7 SECOND PERIODS. THIS WOULD BE
IDEAL FOR STRONG RIP AND STRUCTURAL CURRENTS, AND A STRONG SOUTHWARD
FLOWING LONGSHORE CURRENT. IF HEADING TO LAKE MI THIS WEEKEND, MAKE
PLANS FOR OUT OF THE WATER ACTIVITIES. I SUSPECT THE CONFIDENCE FOR
THIS FORECAST WILL BE HIGHER BY THIS AFTERNOON.
RAIN AND STORMS ARE POSSIBLE AGAIN ON SUNDAY AFTERNOON/EVENING AS
ANOTHER TROUGH SWINGS THROUGH AND THE COLD FRONT POTENTIALLY GETS
HUNG UP TO OUR SOUTH AND ANOTHER WEAK TROUGH MOVES IN BEFORE HIGH
PRESSURE BUILDS IN FROM THE NORTHWEST. HAVE CHANCES (20-30%) MAINLY
WEST OF IN-15, THEN EAST OF IN 15 CHANCES FOCUS FURTHER SOUTH OF US
30 WHERE THE FRONT COULD GET HUNG UP. HIGHS SUNDAY WILL BE IN THE
MID-UPPER 70S, LOW 80S.
MONDAY WILL BE COOLER AND DRY, WITH HIGHS IN THE 70S. SFC HIGH
PRESSURE/AN UPPER LEVEL RIDGE BUILDS INTO THE GREAT LAKES BRIEFLY,
THEN BY MON NIGHT INTO TUE THE SURFACE HIGH DRIFTS EAST AND THE
UPPER LEVEL RIDGE TAKES ON A SW TO NE ORIENTATION (EXTENDING INTO
THE LOWER GREAT LAKES AND THE NE CONUS). WE'LL BE ON THE PERIPHERY
OF THIS RIDGE, AND AS AN UPPER LOW/SURFACE LOW MOVE THROUGH ONTARIO,
IT BRINGS A TROUGH AND COLD FRONT EASTWARD INTO OUR FORECAST AREA.
THERE IS UNCERTAINTY AS TO WHETHER THE PRECIPITATION CHANCES ARRIVE
MONDAY NIGHT OR CLOSER TO TUESDAY AFTERNOON. EITHER WAY, EXPECT THE
FRONT AND PRECIPITATION/STORM CHANCES TO CROSS FROM WEST TO EAST
THROUGH LATE MON PM INTO TUESDAY. HOWEVER, THE FRONT DOES APPEAR TO
STALL OUT AS IT IS LIMITED BY SUBSIDENCE FROM THE STAUNCH UPPER
RIDGE STILL LINGERING. THIS WOULD RESULT IN A BOUNDARY OVER OUR
FORECAST AREA THAT MAY LINGER INTO THURSDAY OR FRIDAY. FOR NOW, HAVE
20-50% CHANCES TUESDAY (MAINLY NORTH/WEST OF US 24), THEN INCREASING
TO 30-70% BY TUESDAY NIGHT INTO THURSDAY (40-60%). THERE WILL BE
CHANCES FOR THUNDERSTORMS. AT THIS POINT, SEVERE WEATHER IS NOT
EXPECTED. HIGH TEMPERATURES BY TUESDAY COULD REACH BACK INTO THE MID-
UPPER 80S, BUT IT WILL DEPEND ON THE EXTENT OF CLOUD COVER AND
PRECIP.
AVIATION /12Z TAFS THROUGH 12Z SUNDAY/
ISSUED AT 747 AM EDT SAT SEP 12 2026
KSBN LOOKS TO REMAIN VFR THROUGH THE PERIOD, WITH MUCH OF THE
PRECIPITATION ASSOCIATED WITH A WARM FRONT REMAINING ALONG/SOUTH
OF US 24. KFWA WILL LIKELY FLUCTUATE BETWEEN VFR AND MVFR. AS OF
THIS WRITING, THE HEAVIER SHOWERS AND STORMS ASSOCIATED WITH THE
FRONT ARE SOUTHEAST OF A LINE FROM MARION, IN TO OTTAWA, OH--
FOCUSING CLOSER TO LIMA, OH. MODELS SUGGEST A CONTINUED
GENERATION OF SHOWERS AND A FEW STORMS THROUGH THE EARLY
AFTERNOON AROUND THE AREA ASSOCIATED WITH CONTINUED (WEAKER) WARM
AIR/MOISTURE ADVECTION AND INCREASING UPPER LEVEL SUPPORT
(SHORTWAVE INCOMING, COLD FRONT TO THE WEST). CLOUD TOPS HAVE
BEEN COOLING ALONG A LINE FROM ROYAL CENTER, IN UP THROUGH
HILLSDALE, MI--AND SOME OF THE GUIDANCE CREATES SHOWERS WITH
THIS BAND. FOR NOW, BASES ARE HIGHER (7-10KFT) WITH THIS, SO I
AM UNCERTAIN AS TO WHETHER OR NOT ANY PRECIP DEVELOPS IN THE
NEAR TERM. STILL HELD ONTO THE MVFR CEILINGS/VIS WITH A TEMPO
AND A PROB30 THROUGH THE EARLY AFTERNOON, WITH OBS JUST TO THE
SOUTHEAST OF AROUND 1500-2500 FT AND DEVELOPING INSTABILITY WITH
DAYTIME HEATING. KEPT -TSRA IN THE PROB30 GROUP GIVEN
INSTABILITY AND INCOMING ADDITIONAL FORCING FROM A SHORTWAVE.
OTHERWISE, WE'LL SEE A RETURN TO VFR UNTIL LATE TONIGHT, WHEN
MVFR VISIBILITIES ARE POSSIBLE WITH LIGHT WINDS AND LINGERING LL
MOISTURE.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...NONE.
DISCUSSION...MCD
AVIATION...MCD
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