FXUS63 KLOT 210748 AFDLOT Area Forecast Discussion National Weather Service Chicago/Romeoville, IL 248 AM CDT Sat Mar 21 2026 .KEY MESSAGES... - Early summer-like temperatures are expected this afternoon, followed by blustery and sharply colder conditions on Sunday. - Cooler and drier weather is expected early next week. && .DISCUSSION... Issued at 248 AM CDT Sat Mar 21 2026 The next 48 hours will be a tale of two seasons, with early summer temps today tumbling back to late winter temps for Sunday. A massive upper-level ridge responsible for widespread record high temperatures across the southwest CONUS the past couple days will quickly deamplify into broader WNW flow aloft across much of the CONUS through the weekend. Light easterly flow early this morning will increase and veer southwest by early afternoon in response to a compact low crossing northern Wisconsin this afternoon. This will advect the unseasonably warm airmass associated with the ridge northeastward over the area this afternoon. In fact, 925 hPa temps will near late-March record values of over 20C late this afternoon (per KILX sounding climo). If we can mix to 925 hPa, which seems more likely than not, max temps should at least reach or surpass 80F south of I-80 and the mid 70s toward the Wisconsin state line. Would not be entirely surprised to see temps make a run at 80F at Chicago (far from the daily record of 87F in 2012). The expected deeper mixing will also foster the development of gusty winds potentially to 30 mph by sunset, as well as locally elevated brush fire concerns where rain has been less prevalent the past couple weeks (e.g. toward east-central Illinois). The cold front associated with the low passing to the north today will surge southward late tonight through Sunday morning, resulting in a blustery, colder, cloudy and possibly damp day on Sunday. Temps will struggle to climb out of the 40s through the day, and may remain stagnant in the lower 40s across northeast Illinois. Additionally, a band of anafrontal precip with perhaps an embedded elevated thunderstorm is possible, though marginal mid-level moisture implies that precip chances will be limited to either drizzle or bands of light rain. Broader WNW flow across the northern CONUS will take hold across much of next week, with a continued series of waves crossing somewhere across the Great Lakes region. Cooler but seasonable conditions will prevail as high pressure passes north of the area Monday and Tuesday. A trough passing well to the north on Tuesday is progged to push a stalling cold front near or over the region late Tuesday night into Wednesday, with a stronger trough crossing the Great Lakes region Thursday into Thursday night. The cold front with Thursday's system is favored to still south of the area, leading dry conditions amid colder temps for Friday. Kluber && .AVIATION /06Z TAFS THROUGH 12Z SUNDAY/... Issued at 1247 AM CDT Sat Mar 21 2026 - Gusty southwest winds expected this afternoon - Wind shift to gusty northeast winds and IFR (or lower) conditions expected after 06z Sunday morning. Light southeast winds will develop after sunrise this morning before winds become south-southwest and begin increasing later in the morning. By early afternoon, south-southwesterly winds will likely gust between 20-30kt until sunset (or shortly after at ORD/MDW). A cold front will move across the terminals after 06z Sunday with a brief (an hour or two) wind shift to northwest before the stronger lake enhanced front results in another shift to gusty northeast winds prior to sunrise Sunday. Low stratus is expected to follow quickly (less than an hour or so) behind the wind shift to northeast. For now, introduced IFR CIGS, but certainly possible that CIGS could be LIFR given the initially very shallow nature of this front. - Izzi && .LOT WATCHES/WARNINGS/ADVISORIES... IL...None. IN...None. LM...None. && $$ Visit us at weather.gov/chicago