textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Rain is gradually exiting from west to east for areas south of Interstate 94 tonight. Rain is expected to clear the state prior to sunrise.

- At least Moderate Swim Risk is expected for the Lake Michigan beaches Monday with the possibility for High Swim Risk to develop. Keep out of the water and away from dangerous areas like piers and breakwalls!

- Chances for thunderstorms Tue nt through Wed nt.

- Below normal temps continue.

SHORT TERM

Issued 1055 PM CDT Sun Jun 21 2026

Today and Tonight:

A low pressure system in northeastern MO/central IL will continue to move east toward the Mid Atlantic coast tonight. The stratiform rain shield across the southern Great Lakes region will continue to gradually shift east with the low bringing an end to our rain tonight. Rain is already starting to end from west to east yet tonight. Majority of the rain is expected to end with in the next couple of hours. Some isolate light rain could linger on the back side in the early morning hours, but by and large all the rain will end prior to sunrise Monday. As this low pressure system exits high pressure will be building in from the Northern Plains. Skies will gradually begin to clear as the stable air builds in and winds will become light. Lake shore areas are expected to have the strongest winds of the day coming off of lake Michigan which will keep temperatures cooler in the low to mid 60s. Inland areas will be a bit warmer around the mid 70s. Scattered cumulus clouds are expected Monday afternoon well inland from the lake. Dry conditions are expected to remain through Monday night.

Patterson

LONG TERM

Issued 1055 PM CDT Sun Jun 21 2026

Tuesday through Saturday:

An upper level trough will be descending down from southern Alberta through the northern Plain and into the northern Great Lakes Region late Tuesday. The sfc low will follow a very similar path and is expected to cross through northern Wisconsin Wednesday. POPs are expected to increase across the region from the northwest to the southeast as this sfc low moves in. Instability should rise across the state as a warm front moves through. This will bring not only rain chances but also thunderstorms. The question becomes how much instability and shear for any stronger to severe storms. From some forecast soundings there looks to be narrow CAPE and shear around 30 kts or more. So there is a chance for storms, but each sounding that has both of these features has a cap to contend with as well. So its looking like this could be another conditional strong to severe storms scenario as of now. This is still a couple of days out so things could change, but a time period worth keeping an eye on.

For Thursday and Friday, there is some discrepancies around 500mb among guidance. Some build in ridging aloft faster than others. High pressure is expected to move into the Great Lakes Region briefly but timing and whether or not there could be some lingering PVA aloft is still in question. The PVA aloft with high pressure near the sfc has some low chance POPs (10-30%) mixing in for both Thursday and Friday at times. Available moisture and any forcing at the sfc will really be the catalyst for any light rain during this time (a lake breeze could be just enough forcing, convergence at the sfc, to get light rain). Hard to tell if this will even be an issue if the upper level ridge is in place aloft.

Next decent chance for rain looks to come Sunday into Monday as a trough moves through the western CONUS toward the Great Lakes Region. With there already being discrepancies in the 500mb flow prior to this, models are just continuing to diverge from each other further. Granted timing and strength seem to be the biggest problems so POPs are still hitting a peak of 40-60% Monday.

Patterson

AVIATION

Issued 1055 PM CDT Sun Jun 21 2026

MVFR to VFR conditions are expected through the period. Widespread along and south of the interstate 94 corridor will slowly end from west to east this evening into tonight. MVFR ceilings around 1-3 kft will be possible within the exiting rain. Visibilities are expected to be 6 SM or higher for any terminal experiencing rain. Terminals north of interstate 94 are expected to stay dry with largely VFR conditions. Overcast skies are expected to persist across southern Wisconsin until Monday morning. Mid to high level clouds will start to clear from the northwest to the southeast around sunrise Monday morning. Partly cloudy skies are expected Monday with some diurnal cumulus clouds around 4-6 kft. There is some uncertainty in how expansive any diurnal cumulus clouds could become.

The lingering light southerly winds will eventually turn to easterly then become light and variable by around midnight tonight. Light east to northeast wind are expected to Monday. Winds are expected to be at their strongest along Lake Michigan with sustained wind around 10-15 kts and gusts up to 20 kts. Light and variable winds are expected again Monday night.

Patterson

MARINE

Issued 1055 PM CDT Sun Jun 21 2026

Low pressure around 29.7 inches will track eastward from northeastern Missouri to Ohio by Monday. Light easterly winds will persist across much of the lake with breezy northeast winds across the southern third tonight through Monday. As the low departs and high pressure moves in the pressure gradient will tighten just enough to build waves across the southern Wisconsin nearshore. Waves are expected to be around 4 feet at time Monday afternoon. A Small Craft Advisory is in effect for the elevated waves for areas south of Lighter northerly winds are expected late Monday evening into Tuesday as high pressure around 30.1 inches builds into the region. Winds will become light and variable Tuesday night as the high pressure tracks overhead. By Wednesday, the high pressure will exit to the southeast and low pressure around 29.8 inches moves from the northern Plains into northern Wisconsin. As the low approaches breezy south to southeast winds will develop across the lake.

Patterson

MKX WATCHES/WARNINGS/ADVISORIES

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