IWX issues Area Forecast Discussion (AFD) at May 1, 12:37 PM EDT909
FXUS63 KIWX 011637
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
1237 PM EDT Thu May 1 2025
.KEY MESSAGES...
- Numerous showers with some embedded thunderstorms are expected
through this evening.
- Cooler weather returns this weekend with periodic chances for
light rain showers through early next week.
&&
.UPDATE...
Issued at 1207 PM EDT Thu May 1 2025
The severe weather threat is decreasing this afternoon. A line of
thunderstorms has developed over far east-central Indiana and is now
advancing toward the I-75 corridor. Storms will move through Lima
shortly. This line of storms has the best environment to work
with such that it will grow upstream outside of our forecast
area. To the west over northern IL and northwest IN, showers
are developing but in a lackluster environment characterized by
500 j/kg of CAPE and poor effective shear (accounting for the
anticipated shallow nature for the storms) of 30 knots south of
US 30. Forecast soundings are likewise unimpressive.
Nonetheless, widely scattered shower and thunderstorms are
anticipated through the afternoon ahead of an approaching cold
front amid the aformentioned marginal environment. Can't rule
out small hail from the tallest storms but widespread severe is
very unlikely.
&&
.DISCUSSION...
Issued at 248 AM EDT Thu May 1 2025
Surface warm front currently lifting into the area as midlevel
trough lifts out of the Ozarks. Substantial WAA on the nose of a 40+
kt LLJ aiding in some modest MUCAPE...maintaining SCT thunderstorms
with a chance of some small hail. Environment is increasingly
hostile further north though and forecast soundings only show a few
hundred J/kg of shallow MUCAPE through the morning. Best midlevel
CVA and associated surface low track will be just to our NW through
the morning but our area remains in a region of deep isentropic
upglide with at least neutral instability. This will favor numerous
showers through the morning and beyond with a few embedded
thunderstorms. On the positive side this morning convection and
associated ample cloud debris will limit diurnal destabilization in
our CWA. Furthermore the actual cold front (such as it is) does not
arrive until the evening hours. Severe chances over the OH Valley
appear tied to a prefrontal trough with most hi-res CAM's suggesting
convection develops over southern IN/KY during the early afternoon
and lifts into central/eastern OH late in the day. Our extreme SE
zones could possibly get clipped by a few strong storms during the
early/mid afternoon but the threat appears marginal given limited
instability in our CWA. Strong winds and hail are the main threats
roughly Portland to Ottawa with little/no threat NW of that line.
Initial trough axis and associated weak surface front cross the area
during the late evening. Anticipate a lull in activity by later
tonight into early Fri as we wait for the next northern stream
trough to slowly dig into the region. In fact Friday could end up
being entirely dry given slower arrival of this trough. Another
effect of the slower arrival is much greater support among various
guidance for a cutoff low to develop over our region and meander
over the eastern CONUS (potentially for quite some time). This leads
to chances for rain through at least Tue with considerable
uncertainty on exact timing and placement. Right now, best chances
for rain appear to be Sat and Sun with more diurnally-driven showers
Mon-Tue but this could easily change. Potential upper low will also
keep a lid on highs and limit diurnal drops at night. Highs could
remain stuck in the low/mid 60s with lows in the 40s.
&&
.AVIATION /18Z TAFS THROUGH 18Z FRIDAY/...
Issued at 1237 PM EDT Thu May 1 2025
Breezy southwest winds gusting up to 30 knots this afternoon in
advance of a cold front progged to bring scattered showers and
a few storms to northern IN. Cigs will generally range between
high MVFR and low VFR, with brief IFR/MVFR vis restrictions in
heavier showers. Cold front does move through KSBN this evening,
stalling near or just north of KFWA late tonight into tomorrow
morning. Winds will diminish and cigs will lower into IFR or low
MVFR along and behind the cold front with a few lingering
showers not out of the question.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.
&&
$$
UPDATE...Brown
DISCUSSION...AGD
AVIATION...Steinwedel
Source:
IWX issues Area Forecast Discussion (AFD) at May 1, 12:37 PM EDT---------------
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