953
FXUS63 KIWX 112358
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
758 PM EDT MON AUG 11 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 /00Z TAFS THROUGH 00Z WEDNESDAY/
ISSUED AT 744 PM EDT MON AUG 11 2025
PREDOMINANTLY VFR CONDITIONS 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),
OR WITHIN ANY HEAVIER SHOWERS OR THUNDERSTORMS AT BOTH
SITES TUESDAY AFTERNOON. A STALLED BOUNDARY WEST OF KSBN WITH A
SHORTWAVE RIDING NORTHWARD ALONG IT LATER TONIGHT COULD BE A
FOCUS FOR MOISTURE CONVERGENCE. AS THE LLJ INCREASES THE
MOISTURE CONTENT WE COULD SEE SHOWERS AND MAYBE A FEW STORMS
DEVELOP ALONG/JUST AHEAD OF THE BOUNDARY-THOUGH MUCH OF THE
GUIDANCE KEEPS IT WEST OF KSBN UNTIL AROUND 7-9Z. HAVE VCSH IN
STARTING AROUND 6Z TO ACCOUNT FOR THIS, AND A PROB 30 GROUP FOR
ANY HEAVIER SHOWERS/STORM ACTIVITY IN THE 7-12Z TIME FRAME. I
SUSPECT IT COULD BE SLIGHTLY LATER THAN FORECAST, WHICH WOULD
PUSH IT INTO THE 12-15Z PERIOD AT KSBN, BUT CONFIDENCE IS LOW
GIVEN NEARBY RIDGE LIMITING POTENTIAL. LESSER CLOUD COVER AND
NEARLY VARIABLE WINDS TOWARDS THE 10-13Z TIME PERIOD AT KFWA
COULD LEAD TO SOME BRIEF FOG/BR BEFORE SUNRISE, ESPECIALLY WITH
INCREASING LOW LEVEL MOISTURE. BY THE AFTERNOON HOURS
(ESPECIALLY AFTER 20Z FOR BOTH SITES), THE STALLED FRONTAL
BOUNDARY WILL LIKELY STRENGTHEN ENOUGH TO BEGIN IT'S
SOUTHEASTWARD PROGRESSION ACROSS IN/MI/NW OH, WHICH WILL BE A
FOCUS FOR SHOWERS/STORMS. THIS WOULD BE THE PERIOD MOST LIKELY
TO SEE MVFR CONDITIONS AT BOTH TERMINALS (POTENTIALLY IFR
BRIEFLY WITH ANY STRONGER STORMS/HEAVY RAIN).
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...NONE.
DISCUSSION...STEINWEDEL
AVIATION...MCD
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