FXUS63 KMKX 211849 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 149 PM CDT Sat Jun 21 2025 .KEY MESSAGES... - Hot and humid conditions are expected Today through Monday. Maximum heat indices of 100 to 105 degrees are forecast each day with higher heat indices between 105 and 110 expected through the Milwaukee Metro. An Extreme Heat Warning is in effect for Milwaukee, Racine, and Kenosha Counties, while everywhere else in southern WI is under a Heat Advisory - High swim risk expected for Sheboygan and Ozaukee county beaches and moderate swim risk for Milwaukee, Racine, and Kenosha beaches Tuesday due to life threatening waves and dangerous currents, especially near breakwalls, river/creek inlets, and piers. - Cold front arrives next Monday into Tuesday, but then lingers as a stationary boundary through much of next week. Multiple rounds of strong to severe storms will be possible over the week. && .SHORT TERM... Issued 149 PM CDT Sat Jun 21 2025 Tonight into Sunday Night: Focus through tomorrow night continues to be on the heat. For today, surface dew points didn't really mix at all and if anything the moisture trapped under the inversion helped to create a weak cu field. Dew points have climbed into the middle 70s with temps already into low to mid 90s leading to heat indices in the low to mid 100s with the higher values in the warning counties. With the strong southerly winds, beach hazards remain dangerous in Sheboygan and Ozaukee counties with high waves occurring there today. Going into Sunday, it looks fairly similar to today with the hot and humid air mass in place. Some subtle differences are that the 850-700mb temperatures look to be a few degrees cooler than today and the low level winds aren't quite as strong as they are today. However, we'll be starting at a higher temperature/moisture profile to start the day, so it shouldn't take as long to get to the temps/dews we had today. Overall, didn't see enough to change any headlines and will keep things going as is. Halbach && .LONG TERM... Issued 149 PM CDT Sat Jun 21 2025 Monday through Saturday: Going into Monday, a cold front will approach southern Wisconsin in the afternoon, which should allow for temperatures and dew points to remain high throughout the day. The RAP/HRRR/NAM all show a pocket of drier air advecting northeastward from the south, which seems a bit odd considering the flow out of the Gulf. This could lead to some lower heat indices, but will not be changing anything since we still have heat indices going above 100F. If this trend continues, could see where the warning gets dropped down to an advisory after tomorrow night. This environment ahead of the front will be highly unstable with SBCAPE values reaching 3000 J/kg+. The wind shear profile is unidirectional and fairly parallel to the front. The main speed shear increase is in the lowest 0-3km, so perhaps there could be some bowing clusters that develop and track to the northeast ahead of the front, but overall mainly expect multicell clusters with large hail/downbursts being the main severe risk. The timing has been fairly consistent with the front moving in during the late afternoon from the NW and tracking through to the SE into the evening hours. Beyond this, it gets a bit messy as the upper level flow goes zonal and the boundary gets hung up somewhere in the Great Lakes vicinity. Trying to pin down exactly when the chances for storms/rain will occur will be difficult. Right now, my eye goes to Thursday as there appears to be a deeper low pressure system that develops and brings more widespread lift to the region. Wherever the boundary sets up will be the focus for concern for heavy rainfall or potential severe thunderstorms. Halbach && .AVIATION... Issued 149 PM CDT Sat Jun 21 2025 The main concern through tomorrow is with the winds and low level wind shear that will occur overnight. A locally broken cu deck did develop this morning with ceilings dropping into the 2-3kft range briefly. Those bases have been increasing over the past hour or so and are expected to diminish over the next few hours. Peak wind gusts will be in the 28-34kt range this afternoon before decoupling this evening. A Low Level Jet will develop around 2kft toward midnight/5z which should hit 45kts. Therefore, have left some LLWS in there for after 5z tonight as wind gusts should subside. Winds started gusting around 12z this morning and am expecting the same into tomorrow morning. Peak gusts tomorrow should be slightly lower than what we're seeing today in the 20-25kt range. Halbach && .MARINE... Issued 149 PM CDT Sat Jun 21 2025 The main focus for higher winds and waves across the lake is today into Sunday as a persistent southerly wind under a tight pressure gradient helps to develop high waves from south to north. Due to the cold water temperatures and the warm air moving over the top of it, the amount of gusts mixing down should be limited to just along the land/lake interaction in far SW Lake Michigan near Chicago. These southerly winds should continue into Monday before a cold front drops from north to south across the lake. This front should get to the southern shore of the lake early on Tuesday before potentially shifting back northward over the next few days. With high pressure pushing in from the north, winds should generally be on the lighter side for much of next week. Halbach && .MKX WATCHES/WARNINGS/ADVISORIES... WI...Beach Hazards Statement...WIZ052-WIZ060 until 10 PM Saturday. Heat Advisory...WIZ046-WIZ047-WIZ051-WIZ052-WIZ056-WIZ057- WIZ058-WIZ059-WIZ060-WIZ062-WIZ063-WIZ064-WIZ065-WIZ067- WIZ068-WIZ069-WIZ070 until 7 PM Monday. LM...Small Craft Advisory...LMZ643 until 4 AM Sunday. Small Craft Advisory...LMZ644-LMZ645-LMZ646 until 10 PM Saturday. && $$ 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