557
FXUS63 KIWX 231839
AFDIWX

Area Forecast Discussion
National Weather Service Northern Indiana
239 PM EDT Mon Sep 23 2024

.KEY MESSAGES...

- Scattered showers and thunderstorms arrive later this evening
  and linger through much of the day Tuesday.

- Dry midweek before a low chance (20-30%) of showers late this
  week into the weekend.

&&

.DISCUSSION...
Issued at 125 PM EDT Mon Sep 23 2024

Abundant cloud cover today has effectively kept temperatures
down. Most locations will only see highs in the 60s, although a
few may get up to around 70 degrees.

A low pressure system currently centered over Arkansas and
Missouri will make its way northeastward this evening. Showers
could begin moving into southwest portions of the forecast area
as early as 6-7 pm EDT. While isolated thunder is possible,
chances are slim due to a lack of instability. Showers will
continue through the night, mainly south of US 24. Then as the
low tracks farther northeast by daybreak, shower activity will
also shift northward. The surface low will cross the region
from southwest to northeast (White County, IN to Williams and
Fulton counties in Ohio) on Tuesday afternoon. In its vicinity
and in the warm sector to the southeast will be the best chances
for thunderstorms. It is in this area where bulk shear will be
30-40 kts and CAPE in excess of 1500 J/kg that SPC has extended
the Marginal Risk for severe storms from around 3 pm through 9
pm. Damaging wind or hail could be possible, or even an isolated
tornado.

Wednesday will be mostly dry, but a few lingering showers may
still be possible as the upper trough crosses the Great Lakes.
On Thursday and Friday, the region will again be stuck between
low pressure systems and high pressure will build back in.
It will be dry and temperatures will warm, although it will not
be as hot as last week, with highs confined mainly to the upper
70s or low 80s. Model uncertainty comes into play for the
weekend concerning the position of an upper low to the
southwest and a tropical system near the west coast of Florida.
Consensus is that we should see more rain by Sunday into Monday.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 114 PM EDT Mon Sep 23 2024

Shortwave trough and attendant sfc wave over MO will lift out
across the terminals Tue. Post frontal stratus holding firm so
far through this morning yet should mix a bit higher through
this afternoon. However increasing moisture flux late tonight
and overspread of large, incoming rain shield out of srn/cntrl
IL will bring about widespread IFR conditions by daybreak and
continue through much of Tue.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Beach Hazards Statement until 4 PM CDT this afternoon for
     INZ103.
OH...None.
MI...Beach Hazards Statement until 5 PM EDT this afternoon for
     MIZ177-277.
MARINE...Small Craft Advisory until 5 PM EDT this afternoon for LMZ043-
     046.

&&

$$

DISCUSSION...Cobb
AVIATION...T