textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Patchy fog possible tonight, mainly along the Lake Michigan shoreline and in the Wisconsin River Valley.

- Chance for showers and storms for Sunday night toward east central WI.

- Prolonged period of hot and humid conditions expected for all of next week. Potential for heat indices around to above 100F.

- Additional shower/storm chances accompanying the heatwave Tuesday through the end of the week.

SHORT TERM

Issued 1240 AM CDT Fri Jun 26 2026

Overnight through Sunday night:

Low clouds and fog briefly affected shoreline areas from Milwaukee to Kenosha but has since dissipated. Patchy fog is still possible in river valleys. We can expect a mostly clear skies with few mid and high level clouds overnight, and a light easterly breeze.

With high pressure centered over the Upper Great Lakes, easterly winds will continue across southern WI and keep the (barely) below- normal temperatures going for one more day. Highs will range from the lower 70s near Lake Michigan to around 80 west of Madison under mostly sunny skies.

Our shower/storm chances diminished for Saturday night into Sunday. We still have storm chances for east central WI on Sunday night, as there could be a storm complex that rolls across the north half of the state. This would also coincide with the low level warm front.

Cronce

LONG TERM

Issued 1240 AM CDT Fri Jun 26 2026

Monday through Thursday:

The 925mb temps will surge to 26C on breezy south-southwest winds. This would yield highs around 91-92 with dry adiabatic mixing. Dewpoints should mix out a bit during the afternoon (NBM and bias-corrected model guidance has a high bias), but still top out in the lower 70s. This is VERY hot and humid and the heat advisory criteria of 100 is expected to be met. We would need heat indices of 105 or higher to meet the extreme heat warning criteria. The southerly wind component could allow a lake breeze to develop but not move very far inland.

While the 925mb temps will be similar on Tuesday and our forecast is for Heat indices of 100-104, there is a small chance that clouds from remnant storm complexes could end up over southern WI.

Wednesday and Thursday will continue to have the warm bubble with 925mb temps around 26 over southern WI. Therefore, heat index values will likely continue to be just over 100 but we will continue to watch for clouds to hinder that at times. With low temps over 70 each night during this long stretch of heat and humidity, this prolonged heat wave may warrant an extreme heat warning which can be issued if we are expecting to meet heat advisory criteria for four days in a row.

The ridge over the center of the country looks like it will break down a little on Friday and give us increasing chances (30-45%) for showers and thunderstorms Friday through Saturday. This is during the July 3rd-4th fireworks shows. At this time, there is very low confidence on these storm chances and we will continue to watch closely.

Cronce

AVIATION

Issued 1240 AM CDT Fri Jun 26 2026

Mid level clouds will gradually diminish along the IL border overnight. Patchy fog is possible in the river valleys. Expect mostly sunny skies with a few mid and high clouds during the day and steady easterly winds.

Cronce

MARINE

Issued 1240 AM CDT Fri Jun 26 2026

High pressure continues to track across the Upper Great Lakes and influence the weather pattern through Saturday, with light north to northeast winds. Patchy fog may occur at times.

Low pressure will deepen over the Central Plains for Sunday, bringing breezy southeasterly winds to the lake. Winds then turn southerly and strengthen more into Monday, as the low pressure lifts into the Canadian Prairies. Gusty southerly winds may linger into most of next week. Gales are not expected at this time.

Waves may reach Small Craft Advisory Criteria Sunday night through Monday night, especially north of the North Point Light. Gusty southwest winds up to 25 kt are expected at times Monday through Tuesday.

Cronce

MKX WATCHES/WARNINGS/ADVISORIES

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