Area Forecast Discussion
Issued by NWS Central Illinois
Issued by NWS Central Illinois
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173 FXUS63 KILX 222014 AFDILX Area Forecast Discussion National Weather Service Lincoln IL 314 PM CDT Sun Sep 22 2024 .KEY MESSAGE... - Off and on showers will continue through Tuesday. Storm total rainfall will be greatest along and south of the I-72 corridor where 1 to 2 inches will occur. && .SHORT TERM...(Tonight through Monday) Issued at 314 PM CDT Sun Sep 22 2024 19z/2pm surface analysis shows a cold front between the Illinois River and the I-55 corridor. Scattered showers are beginning to re-develop ahead of the boundary...particularly east of I-55. Think areal coverage will continue to increase over the next couple of hours, resulting in 60-70 PoPs across the E/SE KILX CWA through the remainder of the afternoon and into the early evening. The front will settle southeastward tonight, eventually stalling just north of the Ohio River overnight. With forcing shifting to the south and slightly drier air advecting into the region behind the departing cold front, think early evening showers will come to an end and mostly dry weather can be anticipated overnight. Low temperatures will range from the middle 50s northwest of the Illinois River...to the middle 60s south of I-70. The front will remain stalled across the Ohio River Valley on Monday as a short-wave trough evident on latest water vapor imagery over Colorado approaches from the west. Showers and a few thunderstorms will develop in the vicinity of the boundary...with the best rain chances during the day remaining focused south of I-70. As the wave gets closer and a weak surface low develops and tracks along the front, increased synoptic lift will bring another round of light to moderate rain to much of central Illinois Monday night. Barnes .LONG TERM...(Tuesday through Next Sunday) Issued at 314 PM CDT Sun Sep 22 2024 Showers will be ongoing Tuesday morning, but will shift eastward and come to an end from west to east during the afternoon. Storm total rainfall from yesterday through Tuesday will be greatest along/south of I-72 where amounts of 1 to 2 inches will be common. After a period of dry weather Tuesday night into Wednesday, the forecast for later in the period becomes a bit more complex as a short-wave trough currently over northern Alberta digs southeastward and cuts off over the Mississippi River Valley by mid to late week. The exact evolution of this process remains unclear as synoptic model solutions vary. Another complicating factor will be the presence of a potential tropical system most models are forecasting to track northward through the Gulf of Mexico by Thursday/Friday. This system will likely shunt the upper low N/NW as it approaches the Gulf Coast...potentially bringing an extended period of scattered showers to portions of the Midwest Thursday through the upcoming weekend. Some solutions even suggest tropical moisture may be entrained by the upper low, although this does not seem particularly plausible. End result is a low confidence forecast featuring low chance PoPs for the end of the week into next weekend. Barnes && .AVIATION... (For the 18z TAFs through 18z Monday Afternoon) Issued at 1239 PM CDT Sun Sep 22 2024 17z/12pm surface analysis shows a cold front west of the Illinois River...with scattered showers along and ahead of the front. Ceilings are predominantly MVFR across central Illinois: however, a narrow corridor of IFR persists in the vicinity of the boundary currently impacting KPIA. Based on HRRR/RAP frontal timing, have veered winds to W/NW and improved ceilings to MVFR at KPIA by 20z. Further east, have maintained MVFR ceilings and shower mention through the afternoon. The front will gradually work south of the terminals by early this evening, followed by largely dry conditions with winds veering to NW and eventually to N/NE by late tonight into Monday morning. Forecast soundings suggest MVFR ceilings will persist at most sites, but may temporarily improve to VFR at KPIA this evening before once again lowering to MVFR by dawn Monday. Barnes && .ILX WATCHES/WARNINGS/ADVISORIES... None. && $$