277
FXUS63 KIWX 220544
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
144 AM EDT Sat Jun 22 2024

.KEY MESSAGES...

* Dangerous heat and humidity will persist into Saturday.

* There is a low chance (20-30%) for isolated storms this afternoon
  into early this evening across far ne IN, sc MI and far nw OH.

* A cold front will bring better chances (50-80%) for showers and
  storms late Saturday night into Sunday morning, followed by dry
  and cooler (near normal) temperatures into Monday.

&&

.DISCUSSION...
Issued at 230 PM EDT Fri Jun 21 2024

Pooled moisture/instability near a loosely defined sfc trough may
be enough to generate isolated afternoon convection in far ne IN,
far nw OH and sc MI through early this evening. Similar to
previous days, little shear/flow/forcing to speak of with non-
severe pulse type cells favored (a few gusts > 40 mph). Dry and
hot under a scattered diurnal cu field otherwise with a strong
TN Valley centered upper ridge continuing to dominate.

A series of shortwaves will track out of the Rockies into the Upper
Midwest on Saturday, and through the Great Lakes Sunday into Monday.
This will suppress the positive height anomaly southwest into
the Southern Plains. Southwest flow will deepen in response to
the approaching system tonight through Saturday evening, pushing
the leftover boundary well north of the area with dry
conditions and somewhat breezy southwest winds (gusts 20-25 mph
on Sat). Highs on Saturday should push the mid 90s across the
entire area with peak PM heat indices making one last run at
100F.

Height falls through the Great Lakes will eventually force a cold
front southeast through the area later Saturday night into Sunday
morning with a better opportunity for showers and storms.
Instability magnitudes will be limited given poor diurnal timing and
meager mid level lapse rates. A weakening, outflow dominant, area on
sub-severe convection likely survives into northern portions of the
area later Saturday night in this environment, with the cold front
off to the southeast by peak heating Sunday.

Sfc anticyclone will briefly build in Sunday night into Monday
behind Sunday`s cold front with a welcomed cooldown (seasonable
temps). Theta-e ridge then tries to build in Tuesday into early
Wednesday as warm advection ramps up in advance of the next
approaching upper level wave, and behind the exiting sfc high. This
pattern favors a few convective systems, and possible a very
hot/muggy Tuesday, though confidence remains on the low side
regarding PoPs and temps given lingering model differences. Dry and
seasonable wx then to follow for the second half of the week.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 140 AM EDT Sat Jun 22 2024

Predominantly VFR conditions at the TAF sites today, with mainly
high and mid level clouds around through the period. MVFR/IFR
conditions are possible towards the end of the period (around
3-6z) at KSBN, then probably just beyond the TAF period at KFWA
as a cold front approaches the area. Models have the prevailing
conditions staying VFR at this moment in terms of ceilings, but
as we usually see, a 1-3SM visibility is a reasonable first
guess in the event any heavier showers/storms impact the
terminal. Carried this in a prob30 for KSBN this issuance given
lower confidence. Otherwise, SSW winds will gust up to around
20-25 knots today.


&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Heat Advisory until 8 PM EDT /7 PM CDT/ this evening for
     INZ005>008-012>015-020-022-023-103-104-116-203-204-216.
     Excessive Heat Warning until 8 PM EDT this evening for INZ009-
     017-018-024>027-032>034.
OH...Excessive Heat Warning until 8 PM EDT this evening for OHZ001-
     002-004-005-015-016-024-025.
MI...Heat Advisory until 8 PM EDT this evening for MIZ078>081-177-
     277.
MARINE...None.

&&

$$

DISCUSSION...Steinwedel
AVIATION...MCD