KILX issues Area Forecast Discussion (AFD) valid 2024-05-10T17:58:00ZKILX issues Area Forecast Discussion (AFD) valid 2024-05-10T17:58:00Z 30% north of a Macomb to Paris line) for showers will arrive tonight as a compact upper trough and associated trailing cold front pass through the region. Bumgardner && .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 18z TAFs through 18z Saturday Afternoon) Issued at 1254 PM CDT Fri May 10 2024 Aside from marginal MVFR ceilings around BMI (which should be lifting over the next hour or two), VFR conditions should be predominant throughout the forecast period, barring a brief vis drop with scattered showers overnight. Low VFR ceilings should break up behind the cold front, when a pronounced wind shift (from southwest to northwest) will also occur. Northwest winds will increase, gusting frequently over 20 kt, by mid to late Saturday morning when surface heating aids in mixing. Bumgardner && .ILX WATCHES/WARNINGS/ADVISORIES... None. && $$ ]]>