456
FXUS63 KIWX 130738
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
338 AM EDT TUE MAY 13 2025
KEY MESSAGES
- SCATTERED SHOWERS AND THUNDERSTORMS DEVELOPING BY MIDDAY BOTH
TODAY AND TOMORROW.
- VERY WARM ON THURSDAY WITH HIGHS WELL INTO THE 80S.
- WHILE THE DAYTIME MAY BE PRIMARILY DRY THURSDAY, THERE IS A
CHANCE FOR THUNDERSTORMS THURSDAY EVENING AND OVERNIGHT, SOME
OF WHICH MAY BE SEVERE.
DISCUSSION
ISSUED AT 334 AM EDT TUE MAY 13 2025
THE DRY SLOT OF A CUT-OFF LOW HAS MOVED OVERHEAD ALLOWING FOR A DRY
START TO THE DAY. HIGH CONFIDENCE IN SCATTERED SHOWERS AND
THUNDERSTORMS DEVELOPING BY MIDDAY, HOWEVER. EVERYONE PROBABLY SEES
AT LEAST A SHOWER BUT THE ACTIVITY WILL BE MOST WIDESPREAD ALONG AND
EAST OF I-69, CLOSER TO THE ATLANTIC MOISTURE SOURCE AND IN CLOSE
PROXIMITY TO UPPER-LEVEL VORTICITY MAXIMA ROTATING ATOP THE LOW.
THERE IS VERY LITTLE FLOW ALOFT AND PWATS ARE NEAR THE 90TH
PERCENTILE OF SOUNDING CLIMATOLOGY SUCH THAT HEAVY RAIN IS A
NOTEWORTHY CONCERN FROM ANY THUNDERSTORMS THAT DEVELOP. THE COVERAGE
OF SHOWERS AND STORMS DIMINISHES WITH THE LOSS OF DAYTIME HEATING.
THE LOW MAKES LITTLE FORWARD PROGRESS BY WEDNESDAY, RESULTING IN A
RENEWED CHANCE FOR SCATTERED SHOWERS AND STORMS BY MIDDAY.
VERY WARM ON ON THURSDAY AS THE 576DM RIDGE AXIS MOVES OVERHEAD. THE
RECORD HIGH AT FORT WAYNE IS 91 (2007, 1988) AND 90 AT SOUTH BEND
(1991). FORECAST HIGHS ARE IN THE UPPER-80S ARE INCREASINGLY
PLAUSIBLE AS A MAINLY-DRY DAY COULD BE IN THE CARDS. THE IN-HOUSE
BLEND HAS REALLY BACKED OFF ON POPS (UNSURPRISINGLY) AND THIS TREND
CONTINUED TODAY. AN EML KEEPS THINGS CAPPED DURING THE DAY, THUS,
WE'LL HAVE PLENTY OF INSTABILITY FOR STORMS BUT NO FORCING MECHANISM
UNTIL A COLD FRONT ARRIVES AFTER SUNSET. CAMS WILL ENTER THE
THURSDAY FORECAST DOMAIN LATER TODAY WHICH WILL HELP REFINE THE
THURSDAY FORECAST. I ANTICIPATE THE CAP WILL HOLD UNTIL SUNSET AT
WHICH POINT STORMS AHEAD OF THE COLD FRONT DRIFT IN FROM ILLINOIS.
THE 500-MB JET OVERNIGHT COULD PROVE A BENEFICIAL FORCING MECHANISM
DEPENDING ON ITS PLACEMENT. ALL HAZARDS ARE POSSIBLE SHOULD THE CAP
BE BROKEN.
THIS COLD FRONT STALLS FRIDAY, BISECTING INDIANA AND IS POISED TO BE
THE FOCUS FOR THUNDERSTORMS LATE IN THE DAY. A SECONDARY UPPER-LEVEL
LOW ROTATES ACROSS LAKE MICHIGAN ALONG WITH A RENEWED SURFACE LOW
FRIDAY NIGHT PROMPTING AT LEAST SCATTERED SHOWERS AND STORMS.
MINIMAL SHEAR APPEARS TO LIMIT ANY SEVERE THREAT FRIDAY.
COOLER AND DRY FOR THE WEEKEND BUT WARMING UP THEREAFTER WITH
SHOWERS AND STORMS ARRIVING MONDAY NIGHT; PERHAPS MORE LIKELY
TUESDAY AS THE NEXT LOW ARRIVES.
AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/
ISSUED AT 1121 PM EDT MON MAY 12 2025
EAST-SOUTHEAST FLOW ASSOCIATED WITH A WEAK SURFACE PRESSURE GRADIENT
HAD ALLOWED MOISTURE FLUX TO INCREASE DURING THE PAST SEVERAL HOURS
WITH DEW POINTS REACHING THE LOWER 60S OVER NORTHEAST INDIANA. A
FAIRLY LARGE BAND OF RAIN HAD MOVED NORTH THROUGH NORTHWEST OHIO
AND NORTHEAST INDIANA SINCE 21Z. CEILINGS WERE DROPPING BELOW 030
AT AOH. CEILINGS SHOULD GRADUALLY DROP BELOW 030 FROM THE EAST WITH
AREAS OF IFR CEILINGS DEVELOPING OVERNIGHT. AT THIS TIME, WINDS
SHOULD BE STRONG ENOUGH TO PREVENT FOG FROM FORMING. AVIATION
CONDITIONAL CLIMATOLOGY SHOWS 25% OF ALL OBS AT 12-13Z HAD MVFR
CEILINGS OR LOWER DURING THIS TIME WITH A ESE WIND. THE CLIMATOLOGY
DOES SHOW VERY SLOW IMPROVEMENT THROUGH THE DAY TO VFR WHICH SEEMS
TO MATCH THIS SCENARIO WITH CONDITIONS IMPROVING AT FWA AFTER
18Z.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...NONE.
DISCUSSION...BROWN
AVIATION...SKIPPER
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