Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
Issued by NWS Milwaukee/Sullivan, WI
342 FXUS63 KMKX 121405 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 905 AM CDT Sat Jul 12 2025 .KEY MESSAGES... - Lingering showers this morning gradually diminish. - Chance (20-40%) for a broken north to south line of showers and thunderstorms this afternoon/early evening, especially east of I-39/90. - Dry weather expected Sunday into early Tuesday, then turning warmer and more active with precip chances returning midweek. && .UPDATE... Issued 905 AM CDT Sat Jul 12 2025 A few light showers or sprinkles are expected this morning as low stratus moves through the area. This afternoon, isolated to widely scattered thunderstorms are expected to develop along a weak cold front. Best chances (around 30-40%) will be north of I-94 and east of I-39, with lower chances (15-20%) with southward extent. Brief gusty winds and an instance or two of marginally severe hail will be possible, but any severe weather threat will be quite limited. Convection will move east of the area and diminish by early to mid evening. Boxell && .SHORT TERM... Issued 315 AM CDT Sat Jul 12 2025 Today and Tonight: Showers with a few embedded rumbles of thunder continue across southern WI early this morning as the mid-level shortwave trough gradually works its way out of the area. Will continue to see this shower activity through daybreak, but as the trough shifts further east, will see coverage gradually diminish as well. Behind the showers, likely to see cloudy and misty conditions linger through the morning as well. A drier window is expected mid to late morning, but another upper-level trough is progged to swing through the Upper Midwest through the day. This will be accompanied by a weak cold frontal boundary moving through the region. Ahead of the cold frontal passage will see southerly winds and lingering moisture with PWATs around 1.5 inches across southern WI. As the trough and cold front move through, could see a north to south orientated broken line of showers develop along the front early this afternoon into early evening hours. 00z HREF does show a narrow swath of modest SBCAPE (500-1200 J/kg) build in behind the morning activity and ahead of the frontal passage. Thus may be enough for a few showers to grow tall enough to produce thunder/lightning this afternoon as well. While the potential for stronger storms is limited (SPC risk 1 out of 5) given the favorable upper-level dynamics remaining north and east of southern WI, cannot rule out seeing an isolated storm or two tap into the 30-40 kt 0-6km shear expected to work its way into the region and produce localized gusty winds and small hail. While today does not look to be a washout with plenty of dry time, the 00z CAMs support a quick window for this activity along the cold front this afternoon generally between 20z-00z. Drier conditions expected behind the frontal later this evening. Otherwise, looking a near normal if not slightly cooler conditions today given the cloud cover and scattered shower/storm chances. Looking at highs today in the upper 70s and lower 80s with overnight temps behind the cold front falling into the upper 50s and lower 60s. Wagner && .LONG TERM... Issued 315 AM CDT Sat Jul 12 2025 Sunday through Friday: An upper trough will exit into southeastern Canada and the overall pattern will trend more zonal to start the next workweek. Surface high pressure will dominate our weather regime, though only for a brief time as the western CONUS ridge begins to break down toward midweek. A series of shortwaves will ride the remnant, flat ridge over the northern tier of states, opening our low level flow back to the southwest and bring a seasonably warm/muggy airmass back into the region. High temperatures Monday through Wednesday will trend a few degrees above average, with highs in the mid to upper 80s and heat indices getting into the 90s. Timing midweek rain chances is rather futile given typical differences within the guidance, though the main idea is to expect a few bouts of showers/storms from later Tuesday through Thursday. There is broad agreement that the main upper trough passage looks to be on/around Thursday (give or take). As is typical for the time of year, any heavy rainfall and severe storm hazards will be more of a mesoscale challenge. High pressure enters from the northwest to end the week delivering lower dewpoints and cooler temperatures. Gagan && .AVIATION... Issued 905 AM CDT Sat Jul 12 2025 IFR stratus is moving through the area this morning, ahead of an approaching cold front. Ceilings should scatter and lift later this morning into the early afternoon. Widely scattered thunderstorms are expected to develop along the front, though most locations will remain dry. If convection does affect the terminals, it will be short lived. Winds will turn more westerly this afternoon and evening behind the front. Boxell && .MARINE... Issued 312 AM CDT Sat Jul 12 2025 A broad area of low pressure continues to gradually lift northeastward across WI and Lake Michigan this morning. It looks to eventually merge with a deeper low pressure tracking across Ontario through the morning. Expecting to see increasing southerly winds along with scattered thunderstorm activity across Lake Michigan this morning/afternoon. Then a cold front extending off the low pressure tracking across Ontario will push across Lake Michigan later this afternoon and evening resulting in more westerly winds tonight. Then high pressure will move across the southern tip of Lake Michigan on Sunday, with winds turning southerly and southwesterly as the high moves east. Southerly flow is then expected into at least Monday, before a front becomes stationary over the central portion of the lake through midweek. Wagner && .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