FXUS63 KMKX 181141 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 641 AM CDT Sat Jul 18 2026 .KEY MESSAGES... - Wildfire smoke is expected to return tonight and Sunday with unhealthy air and reduced visibility expected. - High Swim Risk conditions may occur at all southern WI beaches Saturday night. - Numerous thunderstorms, possibly severe, are forecast Monday and Monday night. && .UPDATE... Issued 641 AM CDT Sat Jul 18 2026 The MCS from the early morning hours skirted along the far western portion of the CWA with mostly light to moderate rain. Southeastern Wisconsin should largely stay dry through the rest of the morning as the last of the showers dissipate as CIN has taken over. Things will remain fairly quiet across southern Wisconsin until the cold front returns this afternoon into this evening. As the front moves through and winds shift to northwesterly smoke is expected to return. Based on the Wisconsin DNR's forecast unhealthy conditions for sensitive groups is expected at a minimum. Widespread smoke is expected to arrive tonight and should continue through Sunday. For the open waters of Lake Michigan A Dense Smoke Advisory is in effect this afternoon/evening through Sunday night when smoky conditions are expected to improve again. As winds shift behind the cold front, north to northeast winds are expected to come off Lake Michigan and build waves across southern Wisconsin beaches this evening. There is a high swim risk for Ozaukee, Milwaukee, Racine and Kenosha beaches and a moderate swim risk for Sheboygan county. With the north to northeast winds be sure to steer clear of the northern side of piers and breakwalls. Stay out of the water. The high swim risk is expected to persist through the overnight hours until waves diminish. Patterson && .SHORT TERM... Issued 1134 PM CDT Fri Jul 17 2026 Tonight through Sunday night: The CAMs continue to dissipate the current MCS over west central WI over the next 2-3 hours but will still have at least slight chance PoPs as a wly 850 mb jet of 30 kts and thermal ridge shifts swd into the area just ahead of the approaching cold front. PWATs will increase to 1.6-1.9 inches during the overnight with elevated CAPE of 2000 J/KG expected. The CIN will be weak but so is the forcing. The cold front will track from nw-se across the area from 10-16Z with a continued possibility for development as it moves toward the IL border. Sfc based convection may become possible toward the border by late morning, but much of the expected storm development will be in nrn IL in the afternoon. Nly winds and weak cold advection will then settle over srn WI for the afternoon including a lake breeze boosted by the front. High temps in the middle to upper 80s will likely be reached by noon over far ern WI before cooler lake air moves inland. Heat index values on Sat will range from the upper 80s north of I-94 to the lower 90s south. High pressure will then settle over the nrn Great Lakes and nrn WI Sat nt, then moving to lower MI and Lake Huron on Sun. Cooler low temps in the lower to middle 60s is forecast Sat nt with highs Sun in the upper 70s to lower 80s. The high temp forecast for Sun is accounting for fairly widespread smoke that will arrive Sat nt and continue through Sun. Gehring && .LONG TERM... Issued 1134 PM CDT Fri Jul 17 2026 Monday through Friday: For Mon-Mon nt a couple upper waves over Canada will support a 996 mb low across nrn Ontario. A wly low level jet of 30-40 kt and associated thetae advection will arrive on Mon with fairly widespread showers and storms expected. The cold front and the srn periphery of the shortwave trough will follow Mon nt, but there is uncertainty if the warm front will pass or stall over sw WI or farther west due to the earlier storms and clouds. Nevertheless the baroclinic zone and CAPE gradient will likely be sufficiently close for a additional storms and severe potential over some of the area. Afterward nwly winds and cold advection will prevail on Tue but with temps still near normal. Nwly flow aloft and high pressure gradually moving from the Upper MS River Valley to the Mid Atlantic States is the trend for the remainder of the week. Little to no chances for rain with temps near normal. Gehring && .AVIATION... Issued 641 AM CDT Sat Jul 18 2026 VFR conditions are expected into this afternoon/evening across southern Wisconsin. Southwest winds this morning will give wave to northwest to north winds behind a passing cold front. As winds turn northerly smoke is expected to return to southern Wisconsin. Areas to possibly widespread smoke are expected this evening through Sunday. Visibilities may fall to 1-2 SM with the smoke with cigs of around 2-3 kft. Held off on the lower IFR ceilings and cigs until this evening into early Sunday morning for the TAFs. If smoke moves in quicker those IFR conditions will occur earlier. Light and variable winds will settle in across the state tonight into Sunday morning. Patterson && .MARINE... Issued 1134 PM CDT Fri Jul 17 2026 Areas of smoke will continue over the north half of the lake tonight. Otherwise breezy southwest to west winds will develop ahead of a cold front. The low pressure area around 29.7 inches will track from just north of Lake Superior tonight across southern Quebec Saturday afternoon and deepen to 29.4 inches. Its trailing cold front will track from northern Lake Michigan Saturday morning to far southern Lake Michigan by early afternoon. Smoke will return to Lake Michigan behind the cold front and may become dense once again. Breezy northerly winds are forecast behind the cold front and will linger into Saturday evening. Winds then quickly taper Saturday night, as high pressure around 30.1 inches moves over the northern Great Lakes. Northeast to light and variable winds are then expected through Sunday into Sunday night. Gusty south to southwest winds may then develop Monday into Monday night, with gusty west to northwest winds possible into the middle of next week. A Small Craft Advisory will likely be needed Sat nt from Sheboygan to Winthrop Harbor due to breezy northeast winds and building waves. Gehring && .MKX WATCHES/WARNINGS/ADVISORIES... WI...Beach Hazards Statement...WIZ060-WIZ066-WIZ071-WIZ072...7 PM Saturday to 7 AM Sunday. LM...Small Craft Advisory...LMZ643...7 PM Saturday to 2 AM Sunday. Small Craft Advisory...LMZ644-LMZ645-LMZ646...7 PM Saturday to 7 AM Sunday. && $$ 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