IWX issues Area Forecast Discussion (AFD) at Jun 4, 2:16 PM EDT073
FXUS63 KIWX 041816
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
216 PM EDT Wed Jun 4 2025
.KEY MESSAGES...
- Showers and thunderstorms late this afternoon into tonight
will be capable of locally heavy rain and wind gusts in excess
of 40 mph.
- Additional rain chances (30-60%) will linger into Thursday and
Friday, mainly along and southeast of the US 24 corridor.
- Near normal temperatures Thursday through this weekend.
&&
.DISCUSSION...
Issued at 214 PM EDT Wed Jun 4 2025
A frontal boundary, currently draped from southern Michigan
southwest into northwest IN and central IL, will sag slowly
southward into central portions of the local area tonight, and into
southern zones Thursday into Friday under persistent west-southwest
flow aloft. This feature will remain the focus for periods of rain
and embedded thunder through the remainder of the week.
For this afternoon and early evening, the main focus will be on the
very limited svr threat (SPC Marginal Risk) for isolated
strong-severe storms and locally heavy rainfall. The
environment along the sfc portion of the FA in northeast IN,
northwest OH and and south-central MI includes ~1000 j/kg of
MLCAPE and DCAPE, steep 0-3 km lapse rates and 0-6 km bulk shear
magnitudes of 30-35. This hints at the low end potential for
isolated damaging winds (50-60 mph) in stronger cores/mergers.
The greater potential into tonight will be locally heavy rain if
training cells materialize given 850 mb dewpoints of 12-13C and
increased moisture convergence within the frontal slope. With
that said, expectations are for just enough eastward movement
for more of a nuisance flood threat.
The active frontal zone will look to settle over the northern Ohio
Valley Thursday into Friday as Mid Atlantic centered upper ridging
dampens. This will keep low-mid chance PoPs for showers and embedded
thunder mainly confined to our southern zones as several low
amplitude shortwaves track east along the lingering moisture axis.
Consensus forecast guidance continues to favor Sunday afternoon into
Sunday night for the next opportunity for showers and storms. The
forcing mechanism will be a cold front dropping through the leading
edge of a strong upper low diving south from the Canadian
Prairies.
&&
.AVIATION /18Z TAFS THROUGH 18Z THURSDAY/...
Issued at 107 PM EDT Wed Jun 4 2025
A slow-moving cold front is located over KSBN and slowly
creeping east. Passing showers are expected through much of the
period at KSBN, with a period of steady rain anticipated toward
00z. Upstream ceilings of about 500ft are noted, thus confidence
is high in declining ceilings over the next few hours.
At KFWA, satellite depicts some cumulus clouds attempting to
develop beneath a thin veil of stratus. Cannot rule out
thunderstorms this afternoon and evening after sunset. I
contemplated introducing TS in the 03-06z window due to CAMs
guidance. Alas, will see how this late-afternoon period plays
out when instability will be best. Otherwise, a decline in
ceilings is anticipated but the timing of this is uncertain.
Residual dry air and the NNE motion of the precipitation are
delaying such ceilings in the meantime.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Air Quality Alert from midnight EDT /11 PM CDT/ tonight to
midnight EDT /11 PM CDT/ Thursday night for INZ005>009-
012>015-017-018-022>027-032>034-103-104-116-203-204-216.
OH...None.
MI...None.
MARINE...None.
&&
$$
DISCUSSION...Steinwedel
AVIATION...Brown
Source:
IWX issues Area Forecast Discussion (AFD) at Jun 4, 2:16 PM EDT---------------
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