863
FXUS63 KIWX 232353
AFDIWX

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

.KEY MESSAGES...

- Rain showers will expand in coverage overnight with greatest
  coverage expected across northeast Indiana and northwest Ohio
  late night.

- Scattered showers and storms expected later Tuesday
  afternoon/early Tuesday evening. An isolated strong to severe
  thunderstorm is possible.

- 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 /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 744 PM EDT Mon Sep 23 2024

Backing of low level flow downstream of Central Plains upper
trough has allowed for some renewed advective forcing to spread
some light rain showers back across northern Indiana south of
the US 24 corridor. Some question as to how far north these
showers will progress this evening given more impressive
mid/upper level forcing remains upstream. During the overnight
hours, an upper level jet stream will nose northeast across the
Ohio River valley, placing northeast Indiana in more favorable
synoptic positioning for vertical motion. Will continue trend of
prevailing showers overnight at terminals, with greater
confidence at KFWA. Cigs will likely fluctuate between MVFR/VFR
this evening, but renewed moist advection overnight into early
Tuesday should bring back more IFR conditions. The earlier onset
of improving conditions Tuesday is expected at KFWA as sfc low
track would place KFWA in a weak warm sector, with slower
improvements at KSBN. The upstream upper level vort should
dampen across the southern Great Lakes Tuesday, but could
provide impetus for scattered showers/storms Tuesday
afternoon/early evening. With still some uncertainty as to
instability magnitudes, will hold off on TS mention at this
time.

&&

.IWX WATCHES/WARNINGS/ADVISORIES...
IN...Beach Hazards Statement until 9 PM CDT this evening for INZ103.
OH...None.
MI...Beach Hazards Statement until 10 PM EDT this evening for
     MIZ177-277.
MARINE...None.

&&

$$

DISCUSSION...Cobb
AVIATION...Marsili