Area Forecast Discussion
Issued by NWS Central Illinois
Issued by NWS Central Illinois
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061 FXUS63 KILX 100737 AFDILX Area Forecast Discussion National Weather Service Lincoln IL 237 AM CDT Fri May 10 2024 .KEY MESSAGE... - In the Monday-Tuesday timeframe, there is a 20-30% chance of greater than 0.75" of rainfall in 24 hours. Should this occur, one impact would be additional runoff into area rivers already running high. && .DISCUSSION... Issued at 237 AM CDT Fri May 10 2024 An upper level wave is diving southeast across IL this morning. There have been a few showers associated with this wave as it traversed IA and moved into northwest IL, but the latest high res models indicate these showers won`t make it deep into central IL. We will see brief upper ridging this afternoon before another upper wave dives southeast into IL tonight in the northwest flow aloft. An associated surface low will dive southeast across the Great Lakes with an accompanying cold front passing through IL Friday night. We`ll see a chance for showers with this system Friday night, but instability looks rather weak. Believe thunder chances will be rather slim as MUCAPEs look to be less than 100 J/kg according to the HREF mean. Expect benign northwesterly flow aloft for the weekend. We`ll have breezy northwest winds on Saturday with a surface ridge of high pressure moving through the area Saturday night. By Sunday night, an upper low will be passing to the east across Ontario with a southern stream upper low approaching to the southwest. Precipitation chances increase across IL from this southern system Sunday night, with some moderate chances for thunder expected as MUCAPEs are as high as 500 J/kg in west-central IL. The upper low will slowly make its way east across the mid MS River Valley on Mon/Tue and the track will play a key role in how far north the rain extends. Showers with embedded thunderstorms are expected for the start to the week, with the southern half of IL having the best chance for measurable rainfall. Right now, the rainfall ensemble mean for Mon-Tue ranges from around 0.25" in Galesburg to 0.75" in Lawrenceville. Models also have a 20-30% chance for 0.75" of rain in 24 hrs in our southern zones, around I-72 and south, which could add some additional runoff to area rivers that are already running high. Sometime in the Wed-Thu timeframe, we`ll likely see an upper ridge move into the area once again, providing a break from the precip for at least part of the period. There are model differences in the timing of this ridge, but sometime on Thu or Friday, another upper wave is expected to bring showers and storms back to the region. Stay tuned for updates to this late week system as the picture becomes clearer with subsequent model runs. Knutsvig && .AVIATION... (For the 06z TAFs through 06z Friday Night) Issued at 1135 PM CDT Thu May 9 2024 MVFR cloud deck roughly east of a KSPI-KPNT line late evening, with some embedded IFR conditions near KBMI/KCMI. While these should lift a bit as lingering showers exit, some concern for ceilings below 1,000 feet further west overnight. Currently, some breaks in the clouds are seen across the Illinois River valley, and latest HREF guidance favors 50-60% chances of ceilings below 1,000 feet developing between 09-12Z from KPIA-KSPI west. Significant improvements expected to begin by 14Z, with VFR conditions prevailing the remainder of the forecast period. Geelhart && .ILX WATCHES/WARNINGS/ADVISORIES... None. && $$