438
FXUS63 KILX 232025
AFDILX

Area Forecast Discussion
National Weather Service Lincoln IL
325 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.

&&

.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 18z TAFs through 18z Tuesday Afternoon)
Issued at 1254 PM CDT Mon Sep 23 2024

IFR cigs are predominant along the I-72 corridor as an area of
rain and embedded heavy showers spreads over the area. To the
north, MVFR cigs and scattered light showers are in place, but it
appears northward shift of the precipitation shield should take
place this afternoon and evening, spreading the IFR cigs
northward. As the center of this system ejects northeastward close
to the I-72 corridor late this evening, scattered thunderstorms
should approach the I-72 terminals, so have included a period of
VCTS. IFR cigs look to continue through 18Z before significant
improvement, except at KPIA which should see some improvement by
around 16Z. Winds E 5-10 kts this afternoon, becoming light and
variable near the low center, then winds shifting to NW Tuesday
morning around 15Z as the low moves off to the northeast.

37

&&

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

$$