154
FXUS63 KIWX 211806
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
206 PM EDT TUE JUL 21 2026
KEY MESSAGES
- THERE IS STILL A SLIGHT 15-20% CHANCE OF SHOWERS WITH A FEW
THUNDERSTORMS THIS AFTERNOON AND EVENING ESPECIALLY SOUTH OF
US-30. CONFIDENCE IN SEVERE WEATHER OCCURRING IS LOW, BUT
CANNOT COMPLETELY RULE OUT INSTANCES OF ISOLATED DAMAGING WIND
GUSTS OR HEAVY RAIN.
- HIGH WAVES AND STRONG CURRENTS ARE EXPECTED AT SOUTHEAST LAKE
MICHIGAN BEACHES ON TUESDAY THROUGH THURSDAY MORNING. STAY
DRY WHEN WAVES ARE HIGH.
- DRY, COOLER AND LESS HUMID CONDITIONS ARRIVE LATER TODAY AND
PERSIST INTO THE WEEKEND.
DISCUSSION
ISSUED AT 133 PM EDT TUE JUL 21 2026
A SECONDARY COLD FRONT MOVING IN FROM THE NORTHWEST WILL KICK
OFF ANOTHER ROUND OF SHOWERS AND STORMS ACROSS THE FORECAST
AREA THIS AFTERNOON. WITH DEWPOINTS IN THE UPPER 60S TO LOW 70S
AND TEMPERATURES RISING INTO THE MID 80S, CONDITIONS ARE RIPE
FOR A FEW STORMS WITH HEAVY RAIN. MUCAPE IS 2000-3000 J/KG AND
THERE IS MODERATE SHEAR AROUND 40 KTS, SO CANNOT RULE OUT
ISOLATED DAMAGING WIND GUSTS, BUT CONFIDENCE IS LOW IN SEVERE
WEATHER. HOWEVER, THIS FRONT WILL SAG TO THE SOUTH-SOUTHWEST
THROUGH THE EVENING AND SUBSIDENCE AND COOLER/DRIER AIR WILL
FOLLOW, SUPPRESSING CONVECTION.
WINDS WILL SHIFT TO THE NORTH BEHIND THE FRONT TONIGHT, AND LAKE
ENHANCED CLOUDS AND SHOWERS ARE EXPECTED TO DEVELOP OFF OF
SOUTHERN LAKE MICHIGAN LATE TONIGHT AND INTO WEDNESDAY WITH THE
COOLER AIR ALOFT AND WARMER LAKE TEMPERATURES IN PLACE. LOWS ON WEDNESDAY
MORNING WILL BE IN THE 50S WHILE PARTS OF LAKE MICHIGAN SURFACE
WATER TEMPERATURES ARE CURRENTLY IN THE LOWER 60S TO LOWER 70S.
NOT EXPECTING MUCH OF ACCUMULATION FROM ANY OF THE SHOWERS BUT
WILL BE ENOUGH TO KEEP AREAS NEAR THE LAKE DAMP ON WEDNESDAY.
OTHERWISE MILD AND DRY CONDITIONS WILL PREVAIL THROUGH SATURDAY
WITH THE STORM TRACK STAYING SOUTH OF THE AREA. HIGH PRESSURE
WILL START TO BUILD IN ON SUNDAY AND TEMPERATURE WILL WARM BACK
INTO THE UPPER 80S. MOISTURE WILL ALSO RETURN WITH A CHANCE FOR
SHOWERS AND STORMS SUNDAY NIGHT AND MONDAY AS A SERIES OF
SHORTWAVES IS FORECAST TO RIDE OVER THE TOP OF THE RIDGE INTO
THE GREAT LAKES AND OHIO VALLEY.
AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/
ISSUED AT 131 PM EDT TUE JUL 21 2026
WITHIN THIS NORTHWEST FLOW ALOFT REGIME, A SERIES OF COLD FRONTS
MOVE THROUGH THIS AFTERNOON AND EVENING REMOVING THE MOISTURE AND
PROVIDING COLD AIR ADVECTION FROM THE AREA. SOME MODELS ARE THEN
CREATING WHAT APPEARS TO BE LAKE ENHANCED SHOWERS AND LOW
CLOUDINESS. THERE IS QUITE A BIT OF UNCERTAINTY AROUND IF THIS CAN
CREATE MVFR CIGS OR NOT GIVEN FLUCTUATING LAKE TEMPERATURES FROM
RECENT STORMS AND FROPAS. THE RAP HAS MVFR CIGS BUT THE LAV GUIDANCE
APPEARS TO KEEP IT OUT OF THE AREA. TRAJECTORIES PLAY A ROLE IN
POTENTIALLY PUSHING CLOUDS TOWARDS SBN OR NOT. DON'T HAVE ENOUGH
CONFIDENCE IN THESE CLOUDS EDGING FAR ENOUGH EASTWARD TO INCLUDE
WITH THIS ISSUANCE BUT IT IS SOMETHING TO WATCH FOR AT SBN MAINLY
BETWEEN 9Z AND 15Z WED AS DEPICTED ON THE RAP. OTHERWISE, EXPECT VFR
CONDITIONS THROUGH THE PERIOD.
WINDS BECOME MORE NORTHERLY THIS AFTERNOON AND BREEZY CONDITIONS OF
25 KT GUSTS AND 10+ KT SUSTAINED CONTINUE INTO THE EVENING HOURS
BEFORE TAPERING OFF.
IWX WATCHES/WARNINGS/ADVISORIES
IN...BEACH HAZARDS STATEMENT FROM 6 PM CDT THIS EVENING THROUGH
THURSDAY MORNING FOR INZ103.
OH...NONE.
MI...BEACH HAZARDS STATEMENT THROUGH LATE WEDNESDAY NIGHT FOR
MIZ177-277.
MARINE...SMALL CRAFT ADVISORY UNTIL 1 AM EDT THURSDAY FOR LMZ043-046.
DISCUSSION...COBB
AVIATION...ROLLER
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