Area Forecast Discussion
Issued by NWS Central Illinois
Issued by NWS Central Illinois
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864 FXUS63 KILX 221739 AFDILX Area Forecast Discussion...Updated Aviation National Weather Service Lincoln IL 1239 PM CDT Sun Sep 22 2024 .KEY MESSAGES... - Off and on rain chances will continue today through Tuesday. Storm total rainfall will be greatest along and south of the I-72 corridor where 1 to 2 inches will occur. - Cooler and drier weather will return for the middle and end of the week. && .UPDATE... Issued at 1051 AM CDT Sun Sep 22 2024 Short-wave trough evident on 15z/10am water vapor imagery over western Illinois continues to bring widespread light to occasionally moderate rain to the eastern half of the KILX CWA. Latest radar trends show the majority of the rain has shifted east of the I-55 corridor...with only scattered showers lingering further west. As a cold front drops southeastward through the region, additional showers and a few thunderstorms will develop along the boundary this afternoon before the front settles southward toward the Ohio River tonight. Am therefore expecting a lull in precip chances from late morning through early afternoon, followed by an uptick in areal coverage as the front passes this afternoon. Once the strongest forcing shifts south of the area, rain chances will decrease sharply this evening...with locations along/north of I-72 likely becoming completely dry overnight. Given extensive cloud cover and showers, high temperatures today will be considerably cooler than in recent days...with readings ranging from the lower 70s far northwest around Galesburg to near 80 degrees south of I-70. Barnes && .DISCUSSION... Issued at 400 AM CDT Sun Sep 22 2024 A large area of showers with a few embedded thunderstorms was moving eastward into central IL early this morning, as was as far east as highway 29 from Peoria to Springfield. Some weakening trends noted in convection past few hours and expect this to continue as it tracks into eastern IL during this morning. A cold front over central WI into far southeast Iowa and nw MO will push se to near the IL river by early afternoon and nearing I-70 by sunset. A broken band of convection is forecast to develop along and ahead of the cold front near the IL river valley early this afternoon and push into southeast IL this evening. SPC day 1 outlook keeps marginal risk of severe storms south of CWA this afternoon/early evening over southern MO and southern IL where instability will be greater. Ample clouds today along with rain chances to bring cooler temperatures with highs in the lower 70s nw of the IL river and upper 70s to near 80F in southeast IL. This will be a nice break from the heat we had past 8 days with highs in the upper 80s to mid 90s since Sep 14th. Convection chances to lower as the night wears on with mainly isolated chances overnight with main energy/lift focused sw of our area. Lows tonight range from mid to upper 50s from I-55 nw to the mid 60s in southeast IL from I-70 southeast. Monday we will be on the cool side of the front to our south with highest pops (50-60%) in our southern counties and slight chances from I-74 north by Mon afternoon. SPC day2 marginal risk of severe storms Monday afternoon and evening is in far southern IL from Murphysboro to Evansville south. Highs Monday mostly in the lower 70s with upper 60s even possible sw of Springfield. Highs near 75F at Lawrenceville. Low pressure near central AR around dawn Monday to lift ne along the front into the mid MS river valley by sunset Monday and near southeast IL by dawn Tue as upper level trof/low digs into the upper MS river valley and east central plains by Tue afternoon. This will likely spread another wave of convection ne over central and southeast IL during Mon night and Tue morning, and lingering chances of showers in eastern IL Tue afternoon. Seasonably cool day again on Tue with mostly cloudy to overcast skies and rain chances especially in the morning, with highs around 70F in central IL and low to mid 70s in southeast IL. Have generally dry and seasonably cool conditions Tue night through Wed night though nearby upper level trof may keep more low clouds around and isolated light showers (pops less than 20%). Models diverge with evolution of upper level pattern during 2nd half of the week as a strong cutoff low appears to affect the southern and southeast states. Latest GEM and Ecmwf models now bring cutoff low far enough north with qpf over central/se IL Thu into this weekend, while GFS is drier with upper level ridging into IL late this week. Blended models have 20-30% chance of showers Thu through this next weekend with highs in the 70s and lows in the 50s. 07 && .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. && $$