NWS Milwaukee Forecast Discussion
028 FXUS63 KMKX 251937 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 237 PM CDT Thu Sep 25 2025 .KEY MESSAGES... - Patchy fog in river valleys and other low lying areas possible again tonight. - Above normal temperatures return late week into the weekend. && .SHORT TERM... Issued 237 PM CDT Thu Sep 25 2025 Tonight through Friday night: Clear skies, high pressure, and lows dropping toward the dewpoint values tonight will allow for areas of dense, shallow fog again. This should occur in the usual low lying areas, marshes and river valleys. A weak mid level shortwave will track southeast through northern MN and central WI tonight, with the associated surface low dropping across Lake Superior and northern Lower Michigan. This feature may help prevent or break apart any fog that has developed toward central WI. A weak surface cold front is expected to reach Sheboygan around 10 AM, Milwaukee around 12 PM, and Kenosha by 3 PM. The timeline may accelerate with this back door cold front, rushing down the lake quicker than inland areas. It should reach Madison between noon and 3 PM, although diffused in strength. The steep low level lapse rates behind this cold front should give us an area of low clouds along and behind the front for the afternoon and evening, and possibly through the night. That cloud layer looks fairly shallow on forecast soundings, so sprinkles are possible, but showers unlikely. Northeast winds along and behind this front may have a few gusts up to 20 mph, and persistent onshore winds could build wave heights up to 3 feet, but a beach hazards statement does not look necessary at this time (moderate swim risk). High temps tomorrow will be impacted by the front and these associated clouds, with lakeshore temps only in the lower 70s and southwest WI temps in the upper 70s. The cloud cover is uncertain for Friday night. Where it is clear, fog is possible once again. Cronce && .LONG TERM... Issued 237 PM CDT Thu Sep 25 2025 Saturday through Thursday: Another trough of low pressure will swing across the Upper Great Lakes Saturday afternoon. Expect slightly breezy southwesterly winds ahead of this trough, along with a push of warmer air. Highs over southern WI Saturday will be in the lower 80s. Expect northerly winds behind the front Saturday evening, with temps falling back into the lower 50s for most areas. An area of clouds is likely along this front, but probably no showers since the deeper forcing is way farther north. High pressure will sit over the Upper Great Lakes Sunday and Monday. Temperatures will continue to be well above normal for late September, around 80 inland from Lake Michigan. Plenty of sunshine, light winds and a lake breeze can be anticipated each day. This will also continue to be a good setup for morning fog. By Tuesday afternoon, surface high pressure sitting over Ontario and Hudson Bay will push cooler air across Lake Michigan on a northeast breeze. The forecast remains dry for southern WI Tuesday through Thursday. A low pressure trough approaching from the Northern Plains may bring precip to us next weekend. Cronce && .AVIATION... Issued 237 PM CDT Thu Sep 25 2025 The afternoon diurnal cumulus clouds will diminish quickly this evening. Areas of fog, locally dense, are expected once again in the favorable low spots and river valleys. A weak cold front will spread into east central WI Friday morning, race down the lake through late morning, and gradually spread inland as well. Expect a period of MVFR ceilings along and behind this "back door cold front" from mid Friday morning through mid Friday afternoon. There should be improvement to cloud bases up to VFR by mid afternoon. Clouds may linger into the overnight hours, but there is uncertainty. If clouds clear, especially for areas inland from Lake Michigan, then areas of dense fog are possible once again. Cronce && .MARINE... Issued 237 PM CDT Thu Sep 25 2025 Westerly winds are expected tonight as high pressure slides across Illinois and Indiana. Areas of fog are possible again tonight. A frontal boundary associated with a surface trough will then drop through Lake Michigan from the north on Friday, with winds becoming northerly behind the front. Wind gusts up to 20 kt are possible, along with building waves up to 3 feet along the WI and IL Lake Michigan shoreline. This is not high enough for a Small Craft Advisory. Light southerly winds will prevail on Saturday as the weak high departs and a low pressure trough crosses Manitoba and Ontario. Winds will become northerly Saturday night. High pressure will set up over the Upper Great Lakes Sunday and Monday, leading to light and variable winds with a lake breeze each day. Cronce && .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