121
FXUS63 KIWX 212229
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
629 PM EDT Tue May 21 2024

.KEY MESSAGES...

- Potential of strong to severe thunderstorms remains for late
  tonight, mainly west of I-69, but confidence is decreasing.
  The greatest threats are damaging wind gusts.

- Warm and muggy conditions to be replaced by somewhat cooler
  and less humid air later this week into the Memorial Day
  weekend with some additional chances for showers and storms.

&&

.DISCUSSION...
Issued at 223 PM EDT Tue May 21 2024

A robust cumulus field has blossomed across the area today in
the warm sector south of a front that is positioned just north
of the MI/IN border. A few isolated showers or storms could pop
up along this front, but have only kept a slight chance for this
afternoon with soundings showing a capping inversion that will
limit convection. The bigger concern is the potential for severe
weather late tonight. Convection is ongoing ahead of a surface
low across portions of Iowa into Wisconsin. CAMs show a QLCS
developing upstream with the greatest tornado potential across
Iowa, but there is less confidence into the southern Great Lakes
given expected tendency to some outflow dominance through time,
and the fact 0-3km shear will be more marginal with eastward
extent compared to upstream across the MS Valley. The main
shortwave will lift up into northern Michigan, while a second
wave farther south will push across central Illinois into
Indiana. As these waves diverge, some of the CAMs are also
showing a split in the line of storms, meaning that our forecast
area is less favored for severe weather, except for maybe the
northwest corner. The latest SPC Day 1 Outlook maintains a
fairly sharp gradient in severe potential from Enhanced Risk far
northwest to Marginal Risk across southeast which falls inline
with above factors and the gradient in convective environment
expected through time. Given strong DCAPEs, some concern does
exist if integrity of linear convection is maintained to have
some damaging wind gusts late evening/early overnight across the
west/northwest. Hail looks to be a lower end threat, and
focused probably extreme west/northwest.

The cold front stalls just east of the area Wednesday morning,
and so there could still be isolated to scattered showers and
storms, but the risk of severe weather is low. Broad trough
remains over the region going into Thursday, so while the better
moisture and energy will be to the southeast, the is still a
chance of storms in our area south of US 24. Although transitory
ridging moves in on Friday, with will also bring increasing
moisture up from the south and a continued chance for mainly
afternoon convection. A cold front comes through Friday night
with the potential for moderate to heavy rain, and then Saturday
should be dry and noticeably cooler with highs in the 70s. The
more moderate temperatures will persist through Memorial Day as
will periods of showers and thunderstorms.

&&

.AVIATION /00Z TAFS THROUGH 00Z THURSDAY/...
Issued at 625 PM EDT Tue May 21 2024

Very active to the west of the area; however, given the latest
CAMs and dissipation of cu layer, have a TEMPO group at SBN and
VCNTY at FWA. Low confidence that there will be much activity
that reaches northern Indiana. Otherwise, terminals should stay
VFR outside any storms that happen to reach the terminals.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...None.
MARINE...Small Craft Advisory until 5 AM EDT Wednesday for LMZ043-046.

&&

$$

DISCUSSION...Cobb
AVIATION...Skipper