textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Patchy fog will be possible over central and south central Wisconsin around daybreak Saturday morning.

- Dry weather with highs in the 60s this weekend; cooler by Lake Michigan due to onshore winds.

- Widespread showers (80-90 percent chance) and scattered thunderstorms return for Monday through Monday night. Potential for severe weather has developed, with locally heavy rainfall also possible.

UPDATE

Issued 615 AM CDT Sat Apr 25 2026

A deck of very low clouds has worked its way inland through southeastern Wisconsin, and may hold together all the way into Green/Dane/Columbia/Green Lake Counties by sunrise. With this low cloud cover, temperatures may remain lower for longer in southeastern Wisconsin especially, limiting the highs for the day by a few degrees. Farther inland as lake influence diminishes after sunrise, temperatures in the upper 60s to 70 degrees are expected. Otherwise, forecast remains on track, with northeasterly breezes throughout the day.

MH

SHORT TERM

Issued 1107 PM CDT Fri Apr 24 2026

Today through Sunday Night:

Some patchy fog may form over central to south central Wisconsin overnight, primarily around dawn. This fog should quickly mix out after daybreak.

Otherwise, high pressure will linger through the weekend promoting dry conditions. Saturday will feature highs in the mid to upper 60s inland, with cooler temperatures by the lake owing to northeast winds. A few areas along the Wisconsin River Valley may reach 70. Similar conditions are expected Sunday, with a bit more cloud cover aloft as upper level warm advection leans into the region from the west.

CMiller

LONG TERM

Issued 1123 PM CDT Fri Apr 24 2026

Monday through Friday:

A low pressure system is expected to approach the Upper MS Valley Sunday night into Monday. However, model variance regarding the low track remains high between the global models and CAMs, and even within the global model ensembles. At this time, the current envelope of solutions has the low tracking as far south as the WI/IL border to as far north as passing over Duluth, MN. Given the solutions, very different scenarios may play out on Monday regarding our potential severe weather threat.

If a more northerly track occurs, the warm sector of the low would be allowed to surge north into southern WI. As this happens, some thunderstorms may occur on the leading edge of the low-level warm advection Monday morning. With southerly return flow, we'd recover for another round of evening storms along a cold front, with all hazards possible.

If a southerly track pans out, we would likely struggle to get the warm sector into the state as east to northeast flow off of Lake Michigan stymies the northward progression of the warm front. We'd likely still see rain in this scenario, perhaps heavy at times, as isentropic lift occurs over the warm front to our south, but most of the surface- rooted stronger storms would stay to our south in Illinois.

Given this uncertainty, we'll continue to monitor the models through the weekend for important updates. Following the cold front Monday night into Tuesday, a cooler weather pattern is progged to take hold through the rest of the week, characterized by persistent northwest flow, relatively dry conditions, and highs in the upper 50s to low 60s. Still a bit too early to say definitively but frost headlines could be needed by next weekend if model trends hold.

CMiller

AVIATION

Issued 615 AM CDT Sat Apr 25 2026

IFR cloud deck has moved inland from Lake Michigan, stretching through JVL and rising slightly to ~1500 ft. A scattered to broken deck of ~1500 ft clouds may reach as far west as MSN by sunrise. Expecting this deck to slowly whittle away from west to east through the morning hours, but there is potential for lingering overcast skies through the day at lakeshore terminals. Still, expect a rise to MVFR by midday even if overcast skies linger. Expect northeasterly winds to increase through the day, gusting near 20 kt during the afternoon along lakeshore terminals. Winds will diminish overnight, shifting to become easterly, then southeasterly into Sunday morning. A deck of IFR clouds near Lake Michigan are possible again overnight tonight.

MH

MARINE

Issued 1106 PM CDT Fri Apr 24 2026

High pressure will build into northern Wisconsin and the western U.P. through tonight behind departing low pressure, resulting in northerly winds of 10-20 knots tonight into Saturday. Areas of fog will linger overnight, as the drier air mass has been a bit slower to arrive, but fog is expected to ease after daybreak Saturday.

East to northeast winds 10 to 15 knots are expected to develop Saturday night into Sunday as the high shifts eastward ahead of an approaching low pressure system. The low is expected to lift from around northwest Minnesota early Monday to Lake Superior by early Tuesday morning. Winds will increase Monday into Monday night out of the south to southeast ahead of this low. The cooler lake temps should dampen the threat for gales across the lake, but a few severe storms may occur over the southern end of the Lake Monday night.

Breezy west to northwest winds will then develop behind the departing low on Tuesday.

CMiller

MKX WATCHES/WARNINGS/ADVISORIES

WI...None. LM...None.