369 FXUS63 KMKX 112018 AFDMKXArea Forecast Discussion National Weather Service Milwaukee/Sullivan WI 318 PM CDT Thu Sep 11 2025
.KEY MESSAGES...
- Dense fog is possible tonight, especially in southeast and east central Wisconsin.
- Chances (20 to 40 percent) for showers and thunderstorms later Friday night into Saturday morning.
- High temperatures climbing above normal through the weekend, with humidity increasing as well.
&&
.SHORT TERM... Issued 318 PM CDT Thu Sep 11 2025
Tonight through Saturday:
With high pressure overhead and light north-northeast flow off of Lake Michigan, we will remain in a conducive environment for dense fog tonight. If we go by trends last night, the first signs of fog should develop closest to the lakeshore and then expand inland. Models are pointing to the area between Manitowoc and Sheboygan for early development prior to midnight, with expansion south and west as the night goes on. If dense fog develops here, it will impact visibility along I-43.
Fog and clouds will diminish quickly Friday morning with daytime heating and mixing. Winds will be out of the east-southeast for the first half of the day so warming may be a little slow. However, southwest winds just above the surface will begin to kick in Friday afternoon and especially in the evening with the low level jet. Inland areas will warm into the 80s under general diurnal cumulus clouds. Highs near the lake will remain in the 70s.
On Friday night, the nose of the LLJ will primarily be pointing into central MN, with the 850mb temp gradient curving from the Twin Cities down through Wisconsin Dells and Lake Geneva. Meanwhile, the right entrance region of an upper jet and also a mid level shortwave trough will slide across central-northeast MN during the early evening. There are a couple of weather scenarios with this setup and models are divided. One camp suggests the development of a convective complex over northern MN that rides across northern WI. Another camp suggests that the complex develops over southeast MN (later) and rides across southern WI Sat morning. Several camps suggest a solution in between. Therefore, still a large amount of uncertainty here and the chance of showers and slight chance of thunderstorms over southern WI between midnight and noon describes the situation at this time. We will probably not have a better idea of how things are going to progress tomorrow night until the 12z meso models come in tomorrow morning.
Cronce
&&
.LONG TERM... Issued 318 PM CDT Thu Sep 11 2025
Saturday through Thursday:
Any lingering showers with a few rumbles of thunder are expected to exit southeast WI by noon Saturday. We will be within the warm sector and have a south to southwest wind by the afternoon. There will likely be a lake breeze along lakeshore, so highs there may not crack 80. Inland areas southwest of Madison should be in the upper 80s. With dewpoints rising into the lower-mid 60s, overnight lows will also be mild in the lower-mid 60s.
Sunday and Sunday night will have a similar story, but with the ridge shifted slightly eastward, so right over WI, it will be even warmer. Highs in the upper 80s inland from Lake Michigan.
A robust, occluding shortwave is expected to cross North Dakota and southern Manitoba Monday afternoon and night. Precip (showers and thunderstorms) from the associated surface front, along with several additional shortwaves, should remain to our west. Therefore, we (srn WI) should remain entrenched within the ridge. Our forecast highs for Mon-Wed are in the upper 80s, with upper 70s to lower 80s along the lakeshore. Dewpoints will be in the 60s and it will feel like late July again.
This ridging pattern may hold for quite a while, possibly all the way into next weekend.
Cronce
&&
.AVIATION... Issued 318 PM CDT Thu Sep 11 2025
Dense fog may develop over southeast and east central WI once again by late evening and persist into Friday morning. Coverage is uncertain, so expect updates. If we go by trends last night, the first signs of fog should develop closest to the lakeshore and then expand inland. Models are pointing to the area between Manitowoc and Sheboygan for early development prior to midnight, with expansion south and west as the night goes on.
Fog and clouds will diminish quickly Friday morning with daytime heating and mixing.
Cronce
&&
.MARINE... Issued 318 PM CDT Thu Sep 11 2025
Dense fog with visibility below 1 mile is possible again tonight, primarily for the west half of Lake Michigan.
High pressure will continue to move into New England tonight through Friday. Low pressure around 29.7 inches will move into the northern Great Plains, allowing winds to turn south to southeast. Showers and some thunderstorms are expected Friday night into Saturday, with southerly winds increasing.
Winds will turn back out of the northeast Saturday night into Sunday, as a frontal boundary shifts south and high pressure around 30.2 inches develops in Quebec.
Cronce
&&
.MKX WATCHES/WARNINGS/ADVISORIES... WI...None. LM...None. &&
$$
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
NWS MKX Office Area Forecast Discussion