textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Increasing humidity and thunderstorm chances for late tonight through Saturday. A 1 out of 5 (marginal) risk for severe storms is forecast Friday. Hail, gusty winds, and lightning will be the main hazards.

- Trending less likely for storm chances through the rest of the weekend as a cold front pushes through and a Hudson Bay high pressure returns to the Upper Great Lakes.

- Next round of rain is expected early next week.

- Hot and humid conditions expected mid to end of next week with some potential for Heat Advisory conditions late next week.

SHORT TERM

Issued 1139 PM CDT Thu Jun 4 2026

Current Overnight through Friday Night:

A broken line of showers and a few rumbles of thunder have tried to work into the area this evening but have largely been stymied by very dry low level air. However, with time, the low levels should begin to moisten as a shortwave trough aloft pushes east into our area this morning and an 850mb moist advection axis leans over into the state this morning. Rain and a few rumbles of thunder will then linger over the area from 3AM through Noon as the shortwave passes and the moisture axis slowly translates eastward.

A lull is expected during the afternoon as subsidence occurs on the backside of the shortwave, but a second shortwave over MN is expected to kick off thunderstorm activity over northern WI Friday afternoon. This storm activity should then track southeast into our area Friday evening between 6PM and 10PM. Provided the skies clear in the subsidence lull we'll have behind the morning rain, moderate instability from 1800 to 2500 J/kg should build over southern WI ahead of the approaching broken line of storms. Mid level lapse rates may approach 7 C/km with effective shear of 30 knots, supporting sufficient storm organization for some gusty winds and hail with the evening storms.

These storms should then largely weaken after sunset as they travel southward, growing more scattered with time, although a few weaker pop-up storms may linger overnight Friday into early Saturday morning.

CMiller

LONG TERM

Issued 1203 AM CDT Thu Jun 4 2026

Saturday through Thursday:

Outflow from Friday's storms is expected to push a cold front through the region Saturday morning. The front is then expected to set up south of the area over IL, while high pressure slowly builds into the region through the rest of Saturday. With the front south of the state, rain chances are looking less likely Saturday. High pressure continues to build Sunday, keeping conditions dry. The familiar easterly wind pattern that plagued us for most of May will briefly return, leading to cooler conditions by the lake with highs in the 60s and 70s, while highs will be in the low to mid 80s far inland. High pressure will then begin to retreat east on Monday, allowing for thunderstorm chances (50 to 80%) to return Monday afternoon and evening.

A strong ridge is then expected to build over the upper midwest mid to late next week, allowing a hot and humid air mass build over the region. The NBM projects highs in the 90s by next Wednesday and Thursday amid dewpoints in the low to mid 70s, which would cause heat indices between 100 and 105. Model trends will have to be monitored for potential heat headlines. Along with the heat, global deterministic models depict a more summer-like pattern, with nebulous chances for thunderstorms at times from mid to late next week given the ample instability.

CMiller

AVIATION

Issued 1220 AM CDT Thu Jun 4 2026

Dry air will cause VFR conditions to hang out until around sunrise this morning, with lower ceilings moving in from the west as widespread rain along a frontal boundary slowly moistens the lower atmosphere and moves east. Some combination of MVFR west of KMSN and VFR east of KMSN should exist through 10Z, then MVFR and IFR ceilings will push east 10-15Z as rain and thunderstorms push in.

Rain and thunder should persist through the morning hours on today, pushing east this afternoon. Low ceilings are then expected to rise and scatter late Friday afternoon. Some additional thunderstorm activity may occur across central and east central Wisconsin this evening as a broken line moves in from the north.

Winds will remain southerly to southwesterly tonight through Friday and light to moderate. Some gusts to 20 knots may occur Friday late morning into the afternoon.

CMiller

MARINE

Issued 1220 PM CDT Thu Jun 4 2026

High pressure over the southeastern US will continue to drift east toward the Atlantic into tomorrow as a low over the Central Plains connects to another low over southwest Ontario as a cold front between the two tracks east into Friday. The Canadian low pressure will track east across the northern Great Lakes through Friday bringing prevailing southwesterly winds to Lake Michigan along with shower and thunderstorm chances tonight through Friday ahead of the cold front. Then expect the cold front to push through the region later Friday into Saturday bringing additional shower and thunderstorm chances along with a more northwest to westerly wind shift behind it into Saturday. Then winds weaken and become more variable as high pressure builds across the region later Saturday into Sunday. Looking ahead to the start of next week will bring an additional low pressure system to develop over the Plains and bring a return of southerly winds to the Upper Great Lakes.

CMiller

MKX WATCHES/WARNINGS/ADVISORIES

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