textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Hot and humid conditions are expected next week, possibly hitting Heat Advisory criteria at times Monday through Thursday.

- There will be a chance for storms Saturday night into Sunday and again later Tuesday through Thursday.

SHORT TERM

Issued 1224 AM CDT Fri Jun 26 2026

Overnight through Sunday:

Patchy fog is possible overnight, primarily toward Lake Michigan. Light to modest easterly winds will persist through Saturday. This will keep lakeshore areas cooler than inland, and also below normal for a couple more days. Look for plenty of cloud cover across southern WI today as low pressure (and associated showers/storms) tracks across IL and IN. The precip will remain south of the WI/IL border.

There is still a chance (30-45%) of showers and maybe a rumble of thunder Saturday night into Sunday morning as a weak "wing" of mid level warm air advection lifts through WI. The chance for thunder is low because of the strongly capped environment and weak mid level lapse rates. This is our first push of warmer and more humid air into the region, but lakeshore max temps (mid- upper 70s) will remain cooler than inland (mid 80s) due to steady southeast winds.

Cronce

LONG TERM

Issued 1224 AM CDT Fri Jun 26 2026

Sunday night through Thursday:

The upper level ridge will settle over the Mid Mississippi River Valley by Monday morning. Some overnight showers are possible (20% chance) in east central WI. Very warm and humid air will work into southern WI on Monday and stick around through the holiday weekend. High temperatures will be in the lower to mid 90s each day, and dewpoints will likely reach 70 (not sure how far above 70, as models seem to be overdoing this element). The NAEFS (ensemble) is showing that this warm of temps is in the 99th percentile compared to climate, has a one-day- every-10-years return interval, and is around 2 standard deviations higher than normal.

This is going to be a prolonged period of hot and humid conditions that will quickly become dangerous for those without air conditioning, especially since overnight temps will remain in the 70s (upper 70s at times). Heat advisories will likely be needed.

Expect chances for thunderstorms at times during this heat wave, although the ability to predict exactly when and where storms could develop will be limited to the day before. This is because storms will likely develop in the Northern Plains, MN and northwest WI areas and then potentially roll into central or southern WI overnight into the next morning. Any of these storm complexes could limit our daily high temperatures and offer a temporary reprieve from the extreme heat, but not the humidity.

Cronce

AVIATION

Issued 1224 AM CDT Fri Jun 26 2026

Mid and high level clouds will increase overnight into Friday as low pressure and associated precip tracks across MO/IL/IN. Cloud bases should lower to around 5000ft as the system passes by during the day, then diminish overnight. Light-modest easterly winds are expected today.

Cronce

MARINE

Issued 1224 AM CDT Fri Jun 26 2026

High pressure over Ontario and the western Great Lakes will dominate today through Saturday with light north to northeast winds. Sunday, low pressure will deepen over the Central Plains, bringing breezy southeasterly winds to the lake. Winds then turn southerly and strengthen Monday (not quite gales) as low pressure exits into the Canadian Prairies. Breezy southerly winds will persist for most of next week. A Small Craft Advisory will likely be needed.

Cronce

MKX WATCHES/WARNINGS/ADVISORIES

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