765
FXUS63 KIWX 211830
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
230 PM EDT Fri Jun 21 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 /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 123 PM EDT Fri Jun 21 2024

An area of high pressure keeps the area devoid of thunderstorms
through much of the forecast period with prevailing VFR conditions.
One thing of note is that the HRRR brings showers into Berrien
county MI between 6 and 12z and that could continue moving inland.
Models take it away from SBN`s area with time so will keep it out of
the TAF for now. Winds back more southerly from westerly during the
taf period, but stay below 10 kts until we get to daytime Saturday.
Gusts at or above 20 kts will be possible midday Saturday into the
afternoon.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Heat Advisory until 8 PM EDT /7 PM CDT/ Saturday for
     INZ005>008-012>015-020-022-023-103-104-116-203-204-216.
     Excessive Heat Warning until 8 PM EDT Saturday for INZ009-017-
     018-024>027-032>034.
     Air Quality Alert until midnight EDT /11 PM CDT/ tonight for
     INZ020-103-203.
OH...Excessive Heat Warning until 8 PM EDT Saturday for OHZ001-002-
     004-005-015-016-024-025.
MI...Heat Advisory until 8 PM EDT Saturday for MIZ078>081-177-277.
MARINE...None.

&&

$$

DISCUSSION...Steinwedel
AVIATION...Roller