Area Forecast Discussion
Issued by NWS Central Illinois

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000 FXUS63 KILX 231554 AFDILX Area Forecast Discussion National Weather Service Lincoln IL 1054 AM CDT Fri Apr 23 2021 .SYNOPSIS... Issued at 330 AM CDT Fri Apr 23 2021 Mostly cloudy skies will prevail today over Illinois along with some light rain showers from I-55 west. More widespread rain showers will overspread central and southeast IL during tonight, with wet weather likely continuing into Saturday. The rain should end over the IL river valley Saturday afternoon, and over the rest of the area by Saturday evening. Seasonably cool temperatures will prevail into this weekend. Highs of 55 to 60 degrees today, upper 50s to lower 60s Saturday, and in the low to mid 60s Sunday. Much warmer conditions are expected Monday and Tuesday, with highs in the mid 70s to lower 80s. && .UPDATE... Issued at 1001 AM CDT Fri Apr 23 2021 Clouds will continue to increase in coverage this afternoon as synoptic-scale ascent becomes enhanced ahead of an upper-level trough lifting into the Southern Plains. Meanwhile, low-level dry air observed by the 12z ILX sounding will mitigate the chance for widespread showers this afternoon. The better chance will arrive later this evening once the lower troposphere saturates. Most locations will receieve 0.25" of rainfall or less through Saturday, but some locations may receive up to 0.75" wherever the frontogenetic forcing/banding precip develops. The rain is on track to exit the region from west to east by Saturday evening. Temperatures will warm near 60 degrees this afternoon as low- level return flow on the western periphery of a departing surface high helps advect a modified Gulf air mass northward into central Illinois. && .SHORT TERM...(Today and tonight) ISSUED AT 330 AM CDT Fri Apr 23 2021 Early morning surface map showed 1023 mb high pressure over western NC/VA into southern WV and ridging westward into the mid MS river valley including southeast IL. A 1004 mb low pressure was along the southern CO/KS border with a warm front extending thru sw OK into ne Texas and near the AR/LA border. Aloft the water vapor loop shows a northern stream short wave trof over the eastern Dakotas while a southern stream trof was over AZ into nw Mexico. Broken to overcast mid level clouds had overspread much of IL during the night while rain showers were south of I-64 over southern IL into central/se parts of MO and tracking eastward. Temps were in the upper 30s to mid 40s over CWA, mildest from Springfield sw. CMI airport was down to 34 from midnight to 1 am until mid level clouds spread in during early overnight and now up to 38F. Latest CAMs have trended slower with arrival of light rain showers from the west during today with weak lift and limited low level moisture. Have lower pops today especially in eastern IL where we have nudged highs up a few degrees. Highs in the mid to upper 50s today, expect upper 50s to near 60 degrees in eastern IL where more peaks of sunshine expected as mid level clouds thin for a time during midday/early afternoon. Winds become breezy SSW today. Best forcing pushes east into IL during tonight as short wave trof approaches IL, with better chance of rain showers, though not getting into southeast IL until late evening or overnight. Very limited instability over CWA thru tonight and have removed the isolated thunderstorms this afternoon and tonight over southern/sw CWA. A little more support for a few thunderstorms in southern/sw IL late this afternoon into tonight. Lows tonight in the mid to upper 40s. .LONG TERM...(Saturday through Thursday) ISSUED AT 330 AM CDT Fri Apr 23 2021 The short wave trof pushes east into IL Sat morning and exits east of IL during Sat afternoon. Continued high chances of rain showers Sat morning especially east of the IL river, then diminish pops from the west during Sat afternoon with the IL river valley dry by Sat afternoon with cloudy skies becoming partly sunny. Brunt of rain showers shift east of IL by sunset Sat. Rainfall amounts between a half and three quarter inches expected over much of the area by sunset Saturday, though lighter amounts by Galesburg where quarter to half inch amounts expected. Highs Sat in the upper 50s and lower 60s, mildest over the IL river valley where more sunshine expected later in the day. Weak 1020 mb high pressure ridge settles over IL/WI by midday Sunday and bringing a nicer spring day to the area with mostly sunny skies and lighter winds. Highs Sunday in the low to mid 60s, mildest over southern/SW CWA. Models show some qpf over the upper MS river valley and possibly as far south as nw IL Sunday afternoon with some increasing clouds over central IL. Strong south winds on back side of high pressure ridge on Monday over IL with gusts 25-35 mph and possibly higher along with a fair amount of sunshine, to bring a nice warm up, with highs in the mid to upper 70s. Highs around 80 to lower 80s on Tuesday with isolated showers/thunderstorms over the IL river valley Tue afternoon. A deep upper level trof into the southern Rockies Tue and into the southern Plains Wed to bring a stronger storm system into IL during midweek. Showers and thunderstorms likely spread east over the area during Tue night into Wed. Low pressure ejecting ne into central IL and then into lower MI Thu to continue high chances of showers and some thunderstorms. Moderate to heavy rains possible from Tue night thru Thu and during that period could also be a risk of stronger thunderstorms. Highs Wed in the low to mid 70s, warmest in southeast IL. Highs Thu range from lower 60s over the IL river valley and around 70 along the Wabash river. && .AVIATION...(For the 12Z TAFS through 12Z Saturday morning) Issued at 555 AM CDT Fri Apr 23 2021 VFR conditions are expected to continue through about sunset across the central IL airports with some sprinkles possible. Broken mid level clouds around 10k ft early this morning to lower to 4-6k ft this afternoon. MVFR ceilings accompanied by some rain showers will spread east over central IL during early evening with IFR to low end MVFR ceilings setting in during overnight with MVFR vsbys from more widespread rain showers. SSW winds to increase to 10-14 kts with gusts around 20 kts by late morning and afternoon. Winds to veer SE this evening and diminish to 5-10 kts. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...MJA SYNOPSIS...07 SHORT TERM...07 LONG TERM...07 AVIATION...07

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