Area Forecast Discussion
Issued by NWS Central Illinois
Issued by NWS Central Illinois
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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. && $$