Area Forecast Discussion
Issued by NWS Chicago, IL
Issued by NWS Chicago, IL
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917 FXUS63 KLOT 262316 AFDLOT Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 616 PM CDT Fri Jul 26 2024 .KEY MESSAGES... - Very warm to hot, humid, and at times stormy pattern returning Sunday into next week. A few strong storms possible Monday. && .DISCUSSION... Issued at 228 PM CDT Fri Jul 26 2024 High pressure remains centered over the Great Lakes this afternoon, resulting in sunny skies and temps slightly below normal for late July. The high will gradually shift east on Saturday, with max temps into the mid 80s under increasing high- level clouds. An elongated upper-level trough extending from southeast Texas through the Lower Mississippi River Valley will drift northward toward the Upper Mississippi River Valley through Sunday while drawing a moisture-rich airmass into the region. Scattered showers and diurnally enhanced thunderstorms are expected to spread across much of the area Sunday amid weak to modest mid- level lapse rates and minimal low-level capping. Locally enhanced forcing within a coupled weakly upper-jet structure combined with the higher PWAT airmass could support a narrow swath of 1"+ rainfall Sunday afternoon. A weak trough over the central Great Plains will phase with the aforementioned trough on Monday. By this time, increasing lapse rates and low-level moisture will yield another window of scattered and diurnally enhanced showers and storms Monday afternoon and evening. While severe convection is not currently expected, favorable thermodynamic profiles within a weakly sheared environment could support pulsing convection with strong wind gusts. Guidance remains generally in agreement with a broad, low- amplitude ridge building across the central CONUS Monday through Thursday, though there has been a weakening trend with the ridge over the past couple days. A weak cold front may stall over or just south and west of the forecast area late Tuesday into Thursday on the periphery of persistent steep mid-level lapse rates over the region. This puts the area in the vicinity of a weak ring-of-fire pattern with at least a couple periods of convection expected during the week. However, timing out these episodes can be difficult to impossible this far out. Either way, seasonably warm and humid conditions with heat index values well into the 90s to perhaps locally 100F appear likely mid to late week. Kluber && .AVIATION /00Z TAFS THROUGH 06Z SATURDAY/... Issued at 614 PM CDT Fri Jul 26 2024 Light easterly winds at press time will tend to turn more southerly with time, and settle between 180 and 160 degrees by sunrise tomorrow. The direction may sneak west of south for a few hours during the morning hours, though speeds should remain light (around or less than 5 kt). A lake breeze will work toward ORD/MDW during the afternoon allowing for winds to turn easterly once again, before they return to southeasterly tomorrow night. Upper-level clouds will stream overhead toward the end of the TAF period. Borchardt && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...None. && $$ Visit us at weather.gov/chicago