Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
Issued by NWS Milwaukee/Sullivan, WI
800 FXUS63 KMKX 022000 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 300 PM CDT Tue Sep 2 2025 .KEY MESSAGES... - Showers are likely (~60-70%) with embedded thunder late tonight through Wednesday ahead of an approaching cold front. - Below normal temperatures expected Wednesday night through the weekend. - Widespread showers (60-80%) and isolated storm are forecast Thursday night with the passage of low pressure. && .SHORT TERM... Issued 300 PM CDT Tue Sep 2 2025 Tonight through Wednesday night: Partly cloudy to brief periods of mostly cloudy skies will continue through the afternoon via daytime heating and fair weather cumulus. A broad trough of low pressure just north of Lake Superior will deepen tnt when a deep upper trough over nrn Manitoba digs toward it. The cyclogenesis will deepen to nearly 996 MB by late afternoon Wed as the low tracks from just north of Lake Superior to nearly James Bay, Canada. Farther south over srn WI, a weak pre-frontal trough and/or outflow boundary currently over se MN and ne IA will shift into areas northwest of Madison along with a band of PVA. PoPs will increase to 30-50 percent over this area this evening. After midnight, PWATs will increase to 1.2-1.3 inches within the 850 mb thermal ridge, ahead of the approaching cold front. Fcst soundings become fairly saturated above the boundary layer with very minimal CAPE for the night and through Wed. The warm, moist advection followed by low level frontogenesis along the cold front is expected to provide enough lift for showers to become likely with embedded thunder. The likely PoPs will be within a narrow band and progress from nw to se across the area, and long duration rainfall is not expected. Nwly winds and cold advection will then drop temps to around 40F inland from the lake for sunrise Thu. Gehring && .LONG TERM... Issued 300 PM CDT Tue Sep 2 2025 Thursday through Tuesday: A sfc ridge will move from the Mid MO River Valley to the Ohio River Valley on Thu, with swly winds and warm advection beginning in the afternoon. A strong shortwave trough approaching from the nw will then bring a fast moving wave of low pressure across central or srn WI for Thu nt. Widespread rainfall is looking likely for much of srn WI. This low will quickly lift newd into Ontario and Quebec contributing to an already large cyclonic flow over Ontario. High pressure will finally arrive for Sat nt-Sun nt. Below normal temps will prevail during this time. The large cyclonic flow over Canada will gradually shift ewd along with high pressure over the Great Lakes. Sly winds and warm advection will thus return for early next week. Gehring && .AVIATION... Issued 300 PM CDT Tue Sep 2 2025 Sct-bkn050-070 fair wx cumulus today, then showers becoming likely late tnt into Wed as a Canadian cold front passes through srn WI. MVFR Cigs will develop north and west of a line from Mineral Point to Madison to Sheboygan during the early morning hours of Wed, with areas of Cigs below 1 kft in this same region. The MVFR Cigs will then expand into se WI by late morning. Cigs will then rise to 3.5-4.0 kft during the early afternoon. Gehring && .MARINE... Issued 300 PM CDT Tue Sep 2 2025 Modest to breezy south to southwest winds will become established across Lake Michigan this afternoon into tonight as low pressure deepens to 29.5 inches over northern Lake Superior. The low will continue to deepen to near 29.4 inches during the day on Wednesday as it progresses toward James Bay, Canada. A cold front will then gradually cross Lake Michigan from north to south for Wednesday afternoon, resulting in a gusty northwest wind shift across the waters. Showers and storms will accompany the passing front on Wednesday with a few storms producing gusty winds. A few waterspouts are also possible, particularly across the northern half of the open waters. 30.0 inch high pressure will settle into the northern Great Plains early Thursday morning, migrating into the western Ohio River Valley by Thursday evening. The feature`s progression will result in a southwest wind shift across the waters during the day Thursday. Winds will become gusty Thursday night as a second area of 29.5 inch low pressure quickly develops in the northern Great Plains. The low will move across Lake Michigan Friday morning, with gusty northwest winds becoming established during the afternoon hours. Wind gusts could thus approach gale thresholds once more Thursday night through Friday afternoon. Showers and isolated storms will accompany the passing low, particularly late Thursday night into early Friday morning. Gehring && .MKX WATCHES/WARNINGS/ADVISORIES... WI...None. LM...None. && $$ Visit us at weather.gov/milwaukee Follow us on Facebook, X, and YouTube at: www.facebook.com/NWSMilwaukee www.x.com/NWSMilwaukee www.youtube.com/NWSMilwaukee