633
FXUS63 KILX 240459
AFDILX

Area Forecast Discussion...Updated Aviation
National Weather Service Lincoln IL
1159 PM CDT Mon Sep 23 2024

.KEY MESSAGES...

- Widespread showers and a few thunderstorms will continue
  tonight, lingering into Tuesday. Additional rainfall looks to be
  around an inch near I-72, with the remainder of the area likely
  to receive over a half inch. Some locally higher amounts are
  possible, with some spotty precipitation amounts exceeding 2
  inches possible.

- Additional rainfall is possible starting Thursday as moisture
  associated with a developing tropical storm system from the Gulf
  of Mexico moves into the region.

&&

.UPDATE...
Issued at 834 PM CDT Mon Sep 23 2024

The next band of showers and a few storms is starting to push into
the forecast area mainly along and south of a Taylorville to
Danville line. Further northwest, expect more patchy drizzle and
isolated showers through midnight followed by scattered showers
later overnight.

Deubelbeiss

&&

.DISCUSSION...
Issued at 325 PM CDT Mon Sep 23 2024

A surface low is situated in southern MO this afternoon, with warm
front extending east of the low into the Ohio Valley. As the low
moves northeastward overnight, the warm front should clip
southeast portions of the ILX forecast area with an increasingly
moist and unstable air mass, resulting in several hundred J/kg
MUCAPE, which looks to remain elevated. This should bring a period
of scattered thunderstorms this evening and overnight to around
the I-72 corridor, with some isolated lightning activity to the
north. 12Z HREF depicts the highest CAPE around 750 J/kg south of
I-70 where the strongest storms could be expected, but likely
below severe limits. SPC continues a Marginal Risk just south of
Clay, Richland, and Lawrence counties for a large hail and locally
damaging wind risk, as well as a potential tornado or two. After
this last wave moves through overnight, producing widespread rain
of a half inch to inch, with locally over 2 inches depicted by
HREF ensembles, showers and thunderstorms should taper off from
west to east during the daytime Tuesday, although a few showers
could continue into the afternoon as an upper level trough digs
southward over the region and begins to cut off.

Wednesday should be dry as the upper low continues to dig
southward to near Arkansas vicinity, meanwhile NHC estimates a
tropical disturbance will have strengthened to Hurricane Helene in
the Gulf of Mexico. The forecast track currently moves through the
FL Panhandle into GA, then potentially hooks back westward due to
influence by the cutoff low, weakening to a depression heading
toward IL. While considerable uncertainty remains in this yet to
develop tropical storm track, the main message is that at least
associated moisture appears likely to circulate back toward IL
late this week through the weekend into early next week, for
additional rain chances in central IL. Doesn`t appear to be a high
likelihood of excessive rainfall as the Appalachians will likely
remove a significant amount of moisture, but several days of rain
chances could prove to bring beneficial moisture to central IL.

Temperatures should continue to be cool Tuesday with the lingering
showers and cloud cover, with highs ranging from around 70 in most
of central IL to mid 70s south of I-70, then as the fairly
stagnant pattern develops with the cut off low to our
south/southwest, we should see highs around the mid 70s for
several days.

37

&&

.AVIATION...  (For the 06z TAFs through 06z Tuesday Night)
Issued at 1158 PM CDT Mon Sep 23 2024

Low pressure centered near St Louis late this evening will lift
across central Illinois overnight into Tuesday morning. Rain and
IFR/LIFR ceilings will accompany the low passage overnight with
the heaviest rain south of PIA to BMI. Light and variable winds
are expected with the low, then will set up out of the northwest
behind the departing low late morning to around midday as
conditions gradually improve back to MVFR and precip chances
diminish. VFR conditions will return later in the day.

Deubelbeiss

&&

.ILX WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$