Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
Issued by NWS Milwaukee/Sullivan, WI
444 FXUS63 KMKX 130245 AAA AFDMKX Area Forecast Discussion...UPDATED National Weather Service Milwaukee/Sullivan WI 945 PM CDT Sun May 12 2024 .KEY MESSAGES... - Showers and thunderstorms have dissipated this evening, with a few showers or storms possible overnight. - Widespread showers with embedded thunderstorms are expected Monday afternoon and evening, mainly along and south of a line from Madison to Port Washington. && .UPDATE... Issued 945 PM CDT Sun May 12 2024 Most of the shower and thunderstorm activity has ended across the area, with the loss of daytime heating and subsequent convective inhibition increasing in the low levels. There may still be some showers and a few storms that develop or move into the area into the overnight hours, as the cold front sags slowly southward toward the area and the 850 mb trough lingers nearby. The front will sag southward into the area Monday, then to the south Monday night. The front will accelerate southward across Lake Michigan first by early to middle afternoon, bringing a quick cool down for lakeshore areas. Low level frontogenesis with the front, along with the advancing 500 mb shortwave trough and 850 mb trough, should bring another round of showers and some thunderstorms by middle afternoon into the evening. The best chances will be across the southern and southeastern parts of the area, similar to most CAMs. The low clouds that develop should limit mean layer CAPE, so not expecting strong to severe storms. Wood && .SHORT TERM... Issued 352 PM CDT Sun May 12 2024 Tonight through Monday night: Scattered thunderstorms developed in a line across northern Iowa and are slowly expanding into southwest WI this afternoon. These are roughly along 700mb frontogenesis and are being triggered with help from a weak mid level shortwave and also by reaching the convective temperature. Low levels are very dry with steep low level lapse rates up to 8000 ft, so gusty winds up to 50 mph are the main threat with these storms, although pea size hail is possible. The next line of scattered storms of interest is currently up in southeast MN and this is associated with the low level cold front (surface to 850mb). This front will make its way into south central WI this evening, but then stall. Convection along it is expected to be weakening as it reaches our forecast area near the Dells mid to late evening. With that boundary stalled over southern WI, additional showers and elevated, weak thunderstorms are expected to develop by midday Monday. Areas toward central WI have lower confidence in these showers, but southern WI has a high probability of showers and storms (80 to 100 percent) during the late afternoon and evening hours. Depending on sky cover Monday morning, a high around 80 could sneak into far southeast WI before the showers develop. This area would be more susceptible to a stronger storm or two, but that would be short lived. Winds will switch to northeast near the lakeshore by late morning in Sheboygan and spread down toward Kenosha through the mid afternoon as a cold front races down the lake faster than inland areas. Lower clouds and much cooler temperatures, along with increasing northeast winds, will help lower clouds develop as the day goes on Monday late afternoon and night. The scattered showers will end from north to south overnight Monday night into Tuesday morning. Models are trending a little slower with clearing the precip out. Cronce && .LONG TERM... Issued 352 PM CDT Sun May 12 2024 Tuesday through Sunday: Southern Wisconsin will get shortwave ridging aloft Tuesday into Wednesday for dry and warm conditions. There looks to be a mid level trough approaching from the west on Wednesday night. Still uncertain on whether thunderstorms develop, but there will also be an approaching cold front. Some weak lift is indicated late Wednesday night into Thursday for shower activity. Highest QPF looks to be east and southeast of the forecast area on Thursday. Surface wind direction could also be tricky on this day. This system kicks well east by Friday for a dry and breezy day for southern Wisconsin. In fact, mostly dry and zonal flow aloft should hold through next weekend. This will very likely result in warm temperatures and no precipitation, although diurnal convection can be expected each day. KPL && .AVIATION... Issued 945 PM CDT Sun May 12 2024 Most of the shower and thunderstorm activity has ended across the area. There may still be some showers and a few storms that develop or move into the area into the overnight hours, as the cold front sags slowly southward toward the area. Light southwest winds and scattered to broken VFR clouds are expected. Low level wind shear conditions are expected from around 03Z to 09Z Monday across area terminals, as west southwest winds around 2000 feet AGL are around 40 knots. The front will sag southward into the area Monday, then to the south Monday night. The front will accelerate southward across Lake Michigan first by early to middle afternoon, bringing a quick wind shift to the northeast for lakeshore terminals, before spreading across the rest of the area. Another round of showers and some thunderstorms are expected by middle afternoon into the evening. The best chances will be across the southern and southeastern terminals. Low clouds with ceilings of 1000 to 1500 feet AGL are anticipated by Monday afternoon and linger into the night. Visibility may drop into the 2 to 5 mile range with the precipitation. Wood && .MARINE... Issued 945 PM CDT Sun May 12 2024 Winds and waves have subsided below Small Craft Advisory levels, so the Small Craft Advisory has been cancelled. A cold front will slowly move southward across Lake Michigan tonight into Monday. Modest south to southwest winds ahead of the front will veer north to northeast behind it. North to northeast winds will increase Monday night into Tuesday night, as weak low pressure around 29.6 inches develops south of the region. High pressure around 30.1 inches near Hudson Bay Wednesday into Friday should bring lighter winds to the region. A Small Craft Advisory will likely be needed for later Monday night into Tuesday night, for increasing northeast winds and building waves. Wood && .MKX WATCHES/WARNINGS/ADVISORIES... WI...None. LM...None. && $$ Visit us at weather.gov/milwaukee Follow us on Facebook, Twitter, and YouTube at: www.facebook.com/NWSMilwaukee www.twitter.com/NWSMilwaukee www.youtube.com/NWSMilwaukee