IWX issues Area Forecast Discussion (AFD) at Jun 30, 3:27 AM EDT836
FXUS63 KIWX 300727
AFDIWX
Area Forecast Discussion
National Weather Service Northern Indiana
327 AM EDT Mon Jun 30 2025
.KEY MESSAGES...
- Two periods of showers/storms are expected, one into the
morning hours and a second, lower confidence chance late
afternoon into this evening. Heavy rain is the most likely
threat, but stronger storms this afternoon and evening could
produce isolated wind damage.
- Drier and less humid Tuesday through early Friday with
seasonable highs in the 80s.
- A return to hot and humid conditions as well as diurnal
showers/storms Saturday to Monday.
&&
.DISCUSSION...
Issued at 312 AM EDT Mon Jun 30 2025
A small area of showers and storms has been trying to expand across
SW portions of the CWA, but is struggling given the overall lack of
convergence or strong forcing. An area of showers and storms was
holding its own and even expanding somewhat across central IN
with this area working NE to impacts SE parts of the forecast
area through 15Z or so. Have went with chc pops in these area
and slgt chc elsewhere to handle the pop up activity expected. The
main threat from any of these will be locally heavy rain given
copious amounts of moisture (PWATs pushing 2" in some areas) and
overall slow movement. The area will likely end up in a lull
for convection prior to the arrival of a cold front and
somewhat stronger trough. However, the final coverage of the
first round of convection as well as any remnant outflows will
determine if we can indeed remain dry or if random
showers/storms pop in an unstable (MLCAPE 1000 to 1500 J/KG) and
most likely uncapped atmosphere. Any areas of weak convergence
could easily pop a few storms with the the most likely areas
late AM into early afternoon possibly being near Lk MI where
lake convergence may hug the shore and allow for some
development. CAMs are struggling on exactly how convection may
unfold with regards to timing, coverage and intensity along and
ahead of the cold front leading to low confidence in the final
outcome. Any limited severe threat will come from development
this afternoon and evening, but even so the best dynamics and
shear lag behind the front resulting in more of a pulse or
loosely organized multicell storm setup with locally heavy rain
and gusty winds the main concern. After coordination, have
capped pops at high chc during the most favorable window late
afternoon into early evening and opted for coverage wording
today and this evening everywhere. Based on some models trends
on a slower arrival to the cold front, pops were also slowed
down wrt to the west to east lowering trend. Everything should
generally be clear by 6Z Tue.
Tuesday through Fri night will be somewhat less humid and
seasonable warm with highs in the 80s as the overall upper level
trough remains in place. Model blend still placing some slgt
chc pops in for Thursday with a subtle disturbance. Not really
buying the slgt chc pops, but will leave alone for now. Upper
level ridging begins to build for the weekend with signals of
590 dm or higher working back in which would yield highs in the
upper 80s to around 90 and at least somewhat increased humidity
as well as diurnal chances for showers and storms.
&&
.AVIATION /06Z TAFS THROUGH 06Z TUESDAY/...
Issued at 1233 AM EDT Mon Jun 30 2025
Showers and thunderstorms are developing north of KLAF, drifting
northeast within the warm sector of a low centered near the UP
of Michigan. SPC mesoanalysis depicts ample instability this
hour and acceptable upper-level support from a vort lobe
rotating through central and southern Indiana. This ought to
keep the PROB30 early this morning in play though confidence is
low overall. Greater confidence in scattered storms passing
through in the afternoon ahead of an upper-level trough and
subsequent cold front. KSBN has a reasonable opportunity to see
two rounds of storms. Meanwhile, the cold frontal storms appear
unlikely to arrive to KFWA given a dwindling TS environment.
&&
.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...None.
&&
$$
DISCUSSION...Fisher
AVIATION...Brown
Source:
IWX issues Area Forecast Discussion (AFD) at Jun 30, 3:27 AM EDT---------------
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