Area Forecast Discussion
Issued by NWS Milwaukee/Sullivan, WI
Issued by NWS Milwaukee/Sullivan, WI
796 FXUS63 KMKX 190956 AFDMKX Area Forecast Discussion National Weather Service Milwaukee/Sullivan WI 456 AM CDT Wed Jun 19 2024 .KEY MESSAGES... - There will be chances for storms this morning over central WI and then again from the mid afternoon into the evening for all of southern WI. On and off thunderstorm chances will then continue into this weekend. - Heat index values will be in the mid 90s over southeast WI today. Head index values will be back in the mid 90s this Friday and Saturday. - A moderate swim risk may occur Thursday morning at Sheboygan County beaches. && .SHORT TERM... Issued 441 AM CDT Wed Jun 19 2024 Today through Thursday: A cold front is expected to slowly sink southeast over the state today. Currently, a weak 500mb wave along the front is causing an area of shower and storm activity over NE IA. This activity should continue northeast into central WI this morning and fade with time. There should be a bit of a lull in activity as the front continues southeast, but by the mid afternoon, convergence along the front and the breaching of convective temps should allow for scattered thunderstorms to form over much of southern WI. Shear will be weak with effective bulk shear only around 10 knots, but shallow inverted v soundings in the lowest 1 to 2 km and PWATs in excess of 1.6 to 1.8 inches will cause torrential downpours and the possiblity of downbursts with any storms that form. Scattered shower and storm activity will continue into the overnight hours and into Thursday morning as the front slowly sags south and stalls in northern IL. Thursday will actually feel cool in comparison to the past few days, as cloud cover, rain and northeasterly flow off of Lake Michigan will dull daytime highs. Highs will be in the 70s over most of southern WI, with 80s near the WI/IL border. Dew points will remain elevated however, keeping some soupiness in the air. CMiller && .LONG TERM... Issued 441 AM CDT Wed Jun 19 2024 Thursday night through Tuesday: Lee troughing along the Rockies is anticipated to create an area of low pressure over the Nebraska panhandle by Thursday night. WAA in association with circulation around this low will bring another surge of warmth north for Friday and Saturday with daytime highs in the mid to upper 80s for Friday and the upper 80s to low 90s for Saturday. Heat indices will reach the 90s both days owing to lingering dew points near 70. The broad WAA over the upper midwest to central plains is expected to promote further chances for convection Thursday night into Saturday morning with the NBM painting broad PoPs of 30 to 45% over southern WI. Models are still keying in on a cold frontal passage Saturday evening with 60 to 70% PoPs as the afformentioned low deepens and approaches Lake Superior. Timing of the front would suggest some of the storms would be strong, but GFS soundings are currently ho-hum, with only 25 knots of effective bulk shear, mid level lapse rates around 6 C/km, 1600 J/kg of SBCAPE, and weak flow evident in the hodographs. This paired with boundary parallel shear would drive quick upscale growth into a squall line along the front Saturday night. We`ll continue to monitor the storm threat as the weekend draws closer. Beyond, temperatures "cool" in the low 80s Sunday and Monday as high pressure sink south into the area behind the front, but heat may return by Tuesday as ridging returns. CMiller && .AVIATION... Issued 423 AM CDT Wed Jun 19 2024 Scattered cloud cover is expected today with a mix of high to low VFR. Showers and storms are expected over central WI this morning, then over most of southern WI during the mid afternoon into the evening as a front slowly sags southeast over the area. Tonight, low ceilings are expected in the post frontal air mass, with cloud bases ranging from 1500 to 2500 feet. Some patchy marine fog may creep inland at KMKE tonight, but certainty regarding timing is low at the moment. Winds will start the day southwesterly and a bit breezy, and will shift northwesterly between 18z and 00z as the front moves through. Speeds should ease with the wind shift. Winds overnight will remain light and north to northeasterly. CMiller && .MARINE... Issued 415 AM CDT Wed Jun 19 2024 A cold front will gradually sink east-southeast over Lake Michigan through today as low pressure approaches James Bay in Canada. Modest southerly to southwesterly winds will prevail through today until winds come around to northerly tonight following the front. In the post-frontal air mass, some areas of marine fog may form tonight. North to northeast winds should then linger into Thursday night, as high pressure moves toward Lake Superior. CMiller && .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