636 FXUS63 KMKX 150937 AFDMKXArea Forecast Discussion National Weather Service Milwaukee/Sullivan WI 437 AM CDT Mon Sep 15 2025
.KEY MESSAGES...
- Patchy dense fog development expected again overnight tonight. Particularly in east central WI toward Sheboygan and in/around the Wisconsin River valley region.
- High confidence in above average temperatures through midweek.
- Rain chances to end the week into next weekend are highly uncertain. Forecast has trended drier for late Wednesday and Thursday.
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.SHORT TERM... Issued 425 AM CDT Mon Sep 15 2025
Today through Tonight:
Patchy morning fog will be possible, with the best chances over east-central WI. Otherwise, once fog dissipates, clear and dry conditions are expected today. Inland temperatures will rise to the mid 80s, while east flow off the lake will hold highs in the upper 70s along the lakeshore.
Tonight, overnight lows will drop into the 50s amid continuing mostly clear skies and subsidence over the region.
CMiller
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.LONG TERM... Issued 425 AM CDT Mon Sep 15 2025
Tuesday through Saturday:
High pressure will remain entrenched over the Upper Great Lakes through Wednesday night. Highs each afternoon will be in the mid 80s with dewpoints in the lower 60s. High clouds may spread over south central WI, including Madison, each afternoon due to anticipated shower/storm development in eastern MN and western WI.
The upper low that has been sitting over the Northern Plains will take on a negative tilt and sink into the central Plains Thursday through Saturday. Showers and thunderstorms are expected along the leading edge of this trough each afternoon, so they will inch closer to southern WI each day. We have small chances already on Thursday, but the higher chance will be over northern WI along a surface convergence zone (along a back door cold front). Chances for showers/storms increase to around 30 percent in southwest WI on Friday, although they will be up against drier easterly air stemming from high pressure over Hudson Bay.
The trough with a leading shortwave pushes into southern WI on Saturday, but it will continue to be a question about how much dry air can win out. That upper trough will eventually make its way across the Upper Great Lakes, but this could be any time between Saturday night and Monday. It will take a couple of days for that trough to cross, so we should see periods of showers and thunderstorms. There is a pretty clear signal for the Northern Plains and at least western WI to heat up once again with a ridge returning.
Cronce
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.AVIATION... Issued 425 AM CDT Mon Sep 15 2025
Patchy morning fog is possible, mainly over the east-central WI this morning. Once fog clears, VFR conditions and light to moderate southeast winds are expected through today.
CMiller
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.MARINE... Issued 425 AM CDT Mon Sep 15 2025
Weakening low pressure around 29.7 inches over the northern Great Plains will remain nearly stationary through at least Wednesday, with broad high pressure of 30.2 inches dominating our weather pattern. Light (10kt or less) easterly winds are expected during this time over Lake Michigan, keeping waves in the 1 to 3 foot range, and usually on the lower end of that range. Will need to continue to monitor for areas of dense fog development from time to time.
CMiller
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.MKX WATCHES/WARNINGS/ADVISORIES... WI...None. LM...None. &&
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NWS MKX Office Area Forecast Discussion