Area Forecast Discussion
Issued by NWS Central Illinois
Issued by NWS Central Illinois
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958 FXUS63 KILX 222324 AFDILX Area Forecast Discussion...Updated Aviation National Weather Service Lincoln IL 624 PM CDT Sun Sep 22 2024 .KEY MESSAGES... - 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 00z TAFs through 00z Monday Evening) Issued at 624 PM CDT Sun Sep 22 2024 Cold front has reached KCMI, and threat of any thunder appears to have ended at the TAF sites. Northwest winds up to 10 knots will become more northerly this evening, then northeast Monday morning. Area of MVFR ceilings impacting KPIA/KBMI at 23Z will push southeast behind the front, though the southwest flank of it will be more scattered. As winds become more northerly, 18Z HREF ensembles suggest areas near KBMI/KCMI will see a period of IFR ceilings between about 03-07Z (40-60% chance). Overall, a more widespread expansion of ceilings just above 1,000 feet will occur late in the night, likely persisting a good portion of Monday. However, some improvement to VFR is anticipated at KPIA potentially as early as 16-18Z. Geelhart && .ILX WATCHES/WARNINGS/ADVISORIES... None. && $$