757
FXUS63 KIWX 120509
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
109 AM EDT TUE AUG 12 2025
KEY MESSAGES
- REMAINING HOT AND HUMID INTO TUESDAY, AND AGAIN THIS WEEKEND.
PEAK AFTERNOON HEAT INDICES THIS WEEKEND WILL BE WELL INTO
THE 90S.
- THERE ARE LOW CHANCES (20-30%) FOR SHOWERS AND STORMS THIS
AFTERNOON INTO TUESDAY MORNING, MAINLY NORTH OF US 24.
- BETTER CHANCES (50-70%) FOR SHOWERS AND STORMS ARRIVE MID
AFTERNOON TUESDAY THROUGH TUESDAY EVENING. ANY STORMS WILL
CARRY A THREAT FOR LOCALLY HEAVY RAINFALL AND GUSTY WINDS.
DISCUSSION
ISSUED AT 206 PM EDT MON AUG 11 2025
MUGGY SOUTHWESTERLY FLOW WILL PERSIST THROUGH AT LEAST TUESDAY
EVENING IN ADVANCE OF A FRONTAL ZONE DRAPED FROM THE WESTERN GREAT
LAKES TO THE SOUTHERN PLAINS. A LEFTOVER MOISTURE AXIS AND SUBTLE
CONVERGENCE ZONE FROM A SHORTWAVE NOW EXITING THE NORTHERN GREAT
LAKES MAY BE THE FOCUS FOR ISOLATED SHOWERS/STORMS THIS AFTERNOON
INTO EARLY THIS EVENING, BEST CHANCES (20-30%) ALONG AND NORTH OF
THE US 24 CORRIDOR. BRIEF DOWNPOURS WILL ACCOMPANY MORE ROBUST
SHOWERS.
ANOTHER CONVECTIVELY INDUCED SHORTWAVE LIKELY LIFTS NORTH-NORTHEAST
THROUGH IA, NORTHWEST IL AND WI TONIGHT INTO TUESDAY MORNING. SHOT
OF WARM/MOIST ADVECTION ON ITS EASTERN FLANK, WITHIN A DEVELOPING 20-
30 KT LOW LEVEL JET, MAY ALLOW CONVECTION TO CLIP OUR NORTHWEST IN
AND SOUTHWEST MI ZONES, BEST CHANCES (20-40%) LATER TONIGHT.
THE BEST OPPORTUNITY FOR SHOWERS AND STORMS (50-70%) WILL ARRIVE MID
AFTERNOON TUESDAY INTO TUESDAY EVENING AS THE UPSTREAM FRONTAL ZONE
FINALLY GETS A PUSH EAST IN RESPONSE TO AN UPPER TROUGH RELEASING
EAST THROUGH THE UPPER MIDWEST AND GREAT LAKES. A MOIST AND UNSTABLE
AIRMASS WILL BE IN PLACE WITH EMBEDDED CONVECTIVELY INDUCED IMPULSES
ALONG AND IN ADVANCE OF THE FRONTAL BOUNDARY ULTIMATELY DETERMINING
THE COVERAGE AND TIMING OF CONVECTION THROUGH THE AREA. THESE
DETAILS REMAIN A LITTLE HAZY AT THIS RANGE AS MODELS TEND TO
STRUGGLE IN RESOLVING THESE SMALLER SCALE WAVES. DEEP MOISTURE AND
POTENTIAL FOR TRAINING SUGGESTS THE POTENTIAL FOR LOCALLY HEAVY
RAINFALL AND FLOODING, WITH GUSTS UP TO 40 MPH POSSIBLE IN
STRONGER WATER LOADED CORES.
COLD FRONT MAY GET HUNG UP NEAR THE US 24 CORRIDOR ON WEDNESDAY WITH
LINGERING HUMIDITY AND LOW CHANCES (20-30%) FOR RENEWED CONVECTION
IF THE BOUNDARY LAYER SUFFICIENTLY RECOVERS. A BREAK FROM THE HEAT
AND HUMIDITY REMAINS ON TRACK POST-FRONTAL INTO THURSDAY AND FRIDAY.
THIS WILL UNFORTUNATELY BE BRIEF AS SUBTROPICAL RIDGING RETURNS THIS
WEEKEND WITH HIGHS BACK NEAR 90F.
AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/
ISSUED AT 104 AM EDT TUE AUG 12 2025
PREDOMINANTLY VFR CONDITIONS ARE EXPECTED AT THE TAF SITES
THROUGH THE PERIOD, ESPECIALLY THE FIRST HALF. MVFR CEILINGS OR
VISIBILITIES ARE POSSIBLE EARLY THIS MORNING AT KFWA WITH BR
POTENTIAL (4SM) AND AGAIN LATE THIS AFTERNOON AND EVENING WITHIN
ANY STORMS. A STALLED FRONTAL BOUNDARY TO OUR WEST WILL SLOWLY
EDGE EAST/SOUTHEASTWARD AND BRING CHANCES FOR RAIN/STORMS TO
THE FORECAST AREA TODAY. RIGHT NOW, MUCH OF THE STORM ACTIVITY
REMAINS CONFINED OVER SOUTHERN LAKE MICHIGAN AND FAR SOUTHWEST
LOWER MICHIGAN. IT'S POSSIBLE KSBN GETS IN ON A FEW SHOWERS OR
EVEN A STORM FROM 6-12Z THIS MORNING SO HAVE LEFT IN A PROB30
GROUP TO ACCOUNT FOR THIS. BETTER CHANCES FOR RAIN/STORMS ACROSS
THE FORECAST AREA ARRIVE BY 21Z THIS AFTERNOON, WITH MEDIUM
CONDIDENCE IN MVFR CEILINGS AND VISIBILITIES (MAYBE IFR BRIEFLY
WITH ANY STRONGER STORMS/HEAVY RAIN).
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...NONE.
DISCUSSION...STEINWEDEL
AVIATION...JOHNSON
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