621
FXUS63 KIWX 230425
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
1225 AM EDT Sun Jun 23 2024

.KEY MESSAGES...

* Relief from the heat arrives later tonight through Monday, but
  briefly returns on Tuesday when afternoon heat indices may
  once again be near 100 degrees.

* Showers and scattered storms expected to move in tonight with
  some potential for wind gusts in excess of 50 mph late
  evening into early overnight hours, best chances in nw IN and
  sw MI.

* There are chances for thunderstorms Tuesday into Wednesday,
  though confidence regarding timing and intensity is low at
  this time.

&&

.DISCUSSION...
Issued at 224 PM EDT Sat Jun 22 2024

No changes in thinking from the previous forecast. Shortwave and
associated deepening sfc low tracking east through the northern
Great Lakes will drag a convective outflow and synoptic cold front
southeast through the area tonight into Sunday. This will bring
rain/storm chances and at least a brief reprieve from the heat.

Dry, hot and somewhat breezy conditions will persist this afternoon
into most of the evening given a capped/dry airmass with 700 mb
temps near 10-11C. Attention late this evening into early Sunday
turns to a line or cluster of deep convection organizing over
eastern IA, southern WI and northern IL during the late aftn hours.
Expectations are for this activity to undergo a general weakening
trend with southeast progression as it outruns more favorable
flow/forcing into much less downstream instability. With that said,
if a more organized upstream convective segment is realized, the
potential for isolated severe wind gusts would exist for areas
mainly northwest of US 24 in the 03-07z window. Non-severe gusts in
the 30-50 mph range appear more likely however with what should
become an outflow dominant convective line. Opted to hold with
likely to categorical PoPs otherwise along the pre-frontal feature
early Sunday given ample pooled moisture.

The main cold front then follows through Sunday morning into early
Sunday afternoon with additional non-zero chances for scattered
showers/storms. A turned over airmass and weakened frontal
convergence behind the early AM composite outflow limits
chances/coverage however. Drier and cooler air (seasonable) does
settle in Sunday afternoon, and more into Monday when sfc high
pressure briefly builds in with pleasant wx.

Return flow quickly ramps back up in response to the next round of
Upper Midwest and Northern Great Lakes height falls. This will allow
a frontal system, first as a warm front and strong low-mid level
theta-e advection late Monday night into Tuesday, followed by a cold
frontal passage Tuesday night or Wednesday to potentially impact the
local area. This type of evolution points to several MCS`s during
this time which will no doubt modulate the positioning/timing of
these frontal features and degree of heating/destabilization.
Confidence in temps and shower/storm chances remain very low as a
result at this forecast range. Higher confidence however in
seasonable temps and dry conditions to follow for the second half of
the week.

&&

.AVIATION /06Z TAFS THROUGH 06Z MONDAY/...
Issued at 1225 AM EDT Sun Jun 23 2024

Line of convection will arrive at KSBN in roughly an hour with
brief MVFR conditions and wind gusts around 30 kts likely. Still
expect arrival in KFWA around 08-09Z with lower coverage of
lightning. MVFR ceilings also still appear likely behind the
line. Models suggest IFR possible but there is little support
for that in upstream obs and will continue to hold with fuel-
alternate MVFR for now. Return to VFR anticipated by the
afternoon with clearing skies and winds relaxing by Sunday
evening.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...None.
OH...None.
MI...Beach Hazards Statement from 4 AM EDT early this morning
     through this afternoon for MIZ177-277.
MARINE...Small Craft Advisory from 4 AM early this morning to 6 PM EDT
     this evening for LMZ043-046.

&&

$$

DISCUSSION...Steinwedel
AVIATION...AGD