FXUS63 KILX 270808 AFDILX Area Forecast Discussion National Weather Service Lincoln IL 308 AM CDT Mon Oct 27 2025 .KEY MESSAGES... - There has been a slight trend southward in Wednesday's storm track, shifting the greater probabilities for beneficial rainfall more towards southern Illinois. Regardless of the storm track, Wednesday will become gusty (30-35 mph areawide). - Dry and seasonably cool weather will return by Halloween. && .DISCUSSION...(through next Monday) Issued at 305 AM CDT Mon Oct 27 2025 This morning, water vapor imagery depicts a very chaotic upper- level pattern across the CONUS. Central Illinois is currently situated between an amplified ridge to the north and a closed low to the south. This synoptic pattern could be described as either a rex block or a split flow regime. Regardless, the entire system will shift eastward tonight as a strong shortwave trough carves into the Missouri Valley. Model guidance has come into more reasonable agreement on the evolution of this trough, with the disturbance becoming a closed low as it pushes into the Ozarks Tuesday night, then pivoting into the Tennessee Valley later Wednesday. Subtle variability remain regarding the depth and timing of this feature, and its attendant surface low. With respect to the GEFS and EPS, the low tracks are about 150 miles apart still, with the GEFS favoring a low track from roughly St. Louis to Carbondale, and the EPS favoring a track from about Jonesboro to Memphis. This key discrepancy could be the difference between central Illinois being within the core of the beneficial rainfall axis (GEFS), or merely the periphery (EPS). After parsing through the 00z suite of ensemble guidance, there does seem to be a clear trend southward, positioning central Illinois on the periphery or gradient of the rainfall axis, while southern Illinois lies within the core of it. The GEFS and NBM are notable exceptions at this point, and you could argue these are now the outliers. We can see this bifurcation in the probabilistic guidance, too. Solution A (EPS, GEPS) exhibits a high (50-70%) probability of exceeding 0.5" south of a Macomb to Terre Haute line, while Solution B (GEFS, NBM) reveals similar probabilities but south of a Davenport to Champaign line. In other words, Solution A supports widespread beneficial rainfall across our CWA, while Solution B is more discriminatory, confining beneficial rainfall mostly across our southern CWA. The latest trends are favoring Solution B for now. Regardless of the exact track, surface winds will become breezy Tuesday night into Wednesday as low pressure rapidly deepens over the region. The 75th percentile of the NBM distribution seems like a decent hedge on gusts, which suggests something in the range of 30-35 mph. Needless to say, Wednesday will be a bit of a raw day. A ridge of high pressure will establish itself Thursday and Friday, bringing dry and seasonably cool weather for Halloween. By the weekend, choppy mid-level flow is expected to return, ushering in another fast-moving frontal system across the region. MJA && .AVIATION... (For the 06z TAFs through 06z Monday Night) Issued at 1220 AM CDT Mon Oct 27 2025 High pressure to the northeast of the central IL terminals will continue to bring a feed of dry air into the area, limiting northward extent of precipitation from a low pressure system passing by to the south. Another system will be tracking into the region near the end of the period, however any associated precipitation or MVFR conditions will hold off until after 06Z. Winds E around 10 kts, increasing to 12-15 kts with gusts up to 20 kts by 16Z. 37 && .ILX WATCHES/WARNINGS/ADVISORIES... None. && $$