IWX issues Area Forecast Discussion (AFD) at May 16, 2:15 PM EDT348
FXUS63 KIWX 161815
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
215 PM EDT Fri May 16 2025
.KEY MESSAGES...
- There is a chance for storms this evening, mainly between 7pm
and 10pm EDT. A few thunderstorms could become severe with
damaging winds the primary threat, mainly south of US 24.
- Cooler and breezy on Saturday.
- Periodic rain chances return next week, mainly Tuesday through
Thursday.
&&
.DISCUSSION...
Issued at 215 PM EDT Fri May 16 2025
A shortwave, 70-80 kt 500 mb jet, and an attendant cold front track
through this evening into the early overnight through the base of an
Upper Midwest upper low. The associated shot of deeper ascent and
some low level moisture return with a developing low level jet
should bring a period of scattered showers/storms to most of the
area this evening. Still cannot rule out a few strong to severe
storms, mainly south of US 24, as shear profiles are favorable
for organized convection. Instability is the limiting factor
however with MLCIN and dry air to overcome, though incoming
height falls/cooling aloft, and some last minute low level
theta-e advection, should eventually allow updrafts to break the
cap with MLCAPE potentially surging into the 1000-1500 j/kg
range (highest southeast of US 24). High DCAPE with steep 0-3km
lapse rates favor a downburst wind threat if any multicell
clusters/lines emerge. Overall confidence in anything more
than isolated strong to severe cells is low, with greater probs
for severe storms off to the south near the primary
moisture/instability axis.
Cold advection on the southern fringes of a stacked low moving east
through the Great Lakes region will provide significantly cooler and
breezy conditions post-frontal later tonight into Saturday. Cyclonic
flow around the low will also allow stratocu to build in for a time,
especially north of US 30 where non zero chances for a rogue
sprinkle/shower will exist. Sunday is definitely the preferred
weekend day weather-wise as high pressure nudges in from the north
with sunshine, lighter winds and slightly warmer temps.
Next week continues to look wet at times as an upper low cuts off
and slowly tracks east through the Central US and Great Lakes. The
greatest chances for rain are the Tuesday through Thursday periods,
with temperatures generally below average for mid-late May.
&&
.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 127 PM EDT Fri May 16 2025
An upper level speed max lifting across downstream portion of
upper trough and an accompanying upper level short wave will
help to advect some increased low level moisture northward late
this afternoon/early this evening. Sfc dew points have mixed out
nicely early this afternoon into the upper 40s to lower 50s. The
challenging part of this convective forecast is trying to assess
extent of moisture return in advance of this short wave tonight
and how much destabilization can occur. Strengthening low/mid
level wind fields and initial dry profiles do suggest potential
of some strong winds with any storms (or showers). Have not made
substantial changes to previous timing of main potential threat
in the 00Z-03Z window for thunder. Otherwise, southerly gusts
to 20 to 25 knots will be maintained in advance of the
associated cold front this evening, with post-frontal west winds
gusting to 30 to 35 knots by Saturday afternoon. Conditions
should remain primarily VFR this period with the exception of
any stronger showers and storms.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...Small Craft Advisory until 5 PM EDT Saturday for LMZ043-046.
&&
$$
DISCUSSION...Steinwedel
AVIATION...Marsili
Source:
IWX issues Area Forecast Discussion (AFD) at May 16, 2:15 PM EDT---------------
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