Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
Issued by NWS Milwaukee/Sullivan, WI
598 FXUS63 KMKX 010219 AAA AFDMKX Area Forecast Discussion...UPDATED National Weather Service Milwaukee/Sullivan WI 919 PM CDT Sun Aug 31 2025 .KEY MESSAGES... - Some fog possible is possible again late tonight into early Monday morning, mainly along and west of the Kettle Moraine. - Shower and thunderstorm chances continue to trend upward (50 to 70 percent or higher) Wednesday into Wednesday night along a cold front. - Below normal temperatures expected Wednesday night into the weekend. && .UPDATE... Issued 919 PM CDT Sun Aug 31 2025 It will be another calm and clear night across southern WI. There is still patchy fog expected, especially over farm fields, marshes, low-lying areas, and river valleys. Temperatures have fallen into the 50s and are expected to drop into the upper 40s inland from Lake Michigan. Cronce && .SHORT TERM... Issued 218 PM CDT Sun Aug 31 2025 Tonight through Monday night: High pressure will remain just east of the area during this period, with dry conditions expected to continue. Some fog is possible again later tonight into early Monday morning, mainly along and west of the Kettle Moraine. Chilly lows in the upper 40s tonight should be below the lowest dew points this afternoon, so patchy fog is forecast. This fog may be more shallow in nature, except in low lying areas and river valleys. The best chances look to be in far western portions of the area. Light and variable winds tonight and Monday night are expected, with light east to southeast winds on Monday. Some diurnal cumulus may occur again in the late morning and afternoon on Monday. Highs Monday should reach the middle to upper 70s, with lower 50s away from the lake Monday night. There may not be much fog Monday night, with low temperatures staying above the Monday minimum dew points. Wood && .LONG TERM... Issued 218 PM CDT Sun Aug 31 2025 Tuesday through Sunday: 500 mb flow becomes northwesterly on Tuesday, as a broad upper level low develops over south central Canada. The high at the surface should slide further east, but allow for another dry day with light southwest winds developing. Highs should be in the middle to upper 70s once again. Models and 500 mb cluster analysis continue to show a deepening 500 mb low shifting southeast into the western Lake Superior area by 00z Thursday, with the main 500 mb low lingering somewhere over northern Ontario into Saturday. At the surface, a cold front is expected to push southeast through the area Wednesday afternoon and early evening, exiting to the southeast by later Wednesday night. There is ample moisture and upward vertical motion with the front, so the trend for higher PoPs of 50 to 80 percent looks reasonable for Wednesday, with decreasing PoPs Wednesday evening. Showers and some thunderstorms are expected with the front. At this time, forecast soundings are showing tall, skinny mean layer CAPE with the best deep layer bulk shear values behind the front. Thus, not expecting any severe weather. A solid 0.25 to 0.50 inches of rainfall may occur, with locally higher amounts possible. Various vorticity maxima with differential CVA rotating through the area at times Wednesday night into the rest of the week may bring periodic chances for showers. There is also a secondary cold front that may push through the area later Thursday night or Friday morning, which may help focus a round of showers. Kept 20 to 30 percent PoPs for this period. Cold air advection on northwest winds should bring much cooler temperatures into the area Wednesday night and linger into Saturday. Highs Thursday may only reach the upper 50s to around 60, which are close to record low maximum temperatures at Milwaukee and Madison. Below normal highs in the middle 60s for Friday and Saturday are forecast, with lows in the lower to middle 40s. These values have been highlighted by ensemble trends and the NBM. High pressure moving into the region for the weekend may bring quiet weather, with slowly moderating temperatures. Wood && .AVIATION... Issued 919 PM CDT Sun Aug 31 2025 Clear skies and light winds are expected into Monday morning. Patchy fog will likely develop again, especially in river valleys, marshes and other low-lying areas. Diurnal cumulus clouds with bases around 3500 ft are anticipated Monday. Cronce && .MARINE... Issued 218 PM CDT Sun Aug 31 2025 High pressure around 30.3 inches will linger over the region into Tuesday, which will continue to bring light winds over Lake Michigan. Southwest winds will become established Tuesday night, as low pressure around 29.6 inches develops near Lake Superior. The low will slowly move to the Ontario and Quebec border Wednesday and Wednesday night, dragging a strong cold front across Lake Michigan. The frontal passage will result in a gusty northwest wind shift across the waters Wednesday night, with gusty winds lingering into Thursday. The current forecast winds remain below gale force thresholds during this period for the open waters, though increases to or above gale force may occur in later forecasts. A Small Craft Advisory will likely be needed for the nearshore waters, for the gusty winds and building waves. Showers and thunderstorms will accompany the passing cold front Wednesday into Wednesday night. It remains too early to pinpoint any possibility for waterspouts with this activity and any showers the rest of the week, though forecast trends will be closely monitored. Breezy west winds will continue through Friday. Wood && .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