225
FXUS63 KIWX 131745
AFDIWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE NORTHERN INDIANA
145 PM EDT TUE MAY 13 2025
KEY MESSAGES
- SCATTERED SHOWERS ALONG WITH A FEW THUNDERSTORMS THIS
AFTERNOON AND AGAIN WEDNESDAY AFTERNOON.
- 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 /18Z TAFS THROUGH 18Z WEDNESDAY/
ISSUED AT 138 PM EDT TUE MAY 13 2025
MODEST HEATING AND AT LEAST SOME INSTABILITY IS ALLOWING FOR A
SLOW INCREASE IN COVERAGE OF SHOWERS WHICH HAVE ALREADY
IMPACTED KFWA. CIGS/VSBYS WILL BE RATHER VARIABLE THROUGH 00Z,
BUT SHOULD RESIDE MAINLY IN THE MVFR RANGE OUTSIDE OF ANY
CONVECTION. FOR THE TIME BEING HAVE REMOVED THE TEMPO GROUP FOR
THUNDER AS CONFIDENCE IN DURATION AND COVERAGE ISN'T QUITE HIGH
ENOUGH TO WARRANT A 4 HOUR PERIOD. SOME LIGHTNING IS NOTED
UPSTREAM (SE OF THE SITE) THAT COULD MAYBE SIGNAL A SMALL PERIOD
OF THUNDER LATER. WILL AMEND IF NEEDED. AT KSBN, SOME SHOWERS
WILL BE NEARBY, BUT CONFIDENCE ON COVERAGE AND IMPACTS THERE IS
EVEN LOWER. HAVE KEPT WITH A POP30 THIS AFTERNOON AND WILL SEE
HOW THE COVERAGE EVOLVES. HIGHER END MVFR CIGS ARE LIKELY TO
STICK AROUND WITH ANY SHOWERS BRINGING A SHOT FOR BRIEF IFR
CIGS.
ANY CONVECTION SHOULD QUICKLY WIND DOWN AFTER 00Z. GIVEN THE
MOIST ATMOSPHERE, WILL NEED TO WATCH FOR STRATUS DECK TO LOWER
OVERNIGHT WITH IFR CIGS AT 1 OR BOTH SITES. WILL FINE TUNE IN
LATER FORECASTS.
IWX WATCHES/WARNINGS/ADVISORIES
IN...NONE.
OH...NONE.
MI...NONE.
MARINE...NONE.
DISCUSSION...BROWN
AVIATION...FRAZIER
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