textproduct: Milwaukee/Sullivan

KEY MESSAGES

- An isolated storm or two (around a 20 percent chance) is possible across far northern and northwestern parts of the area this evening, with gusty winds possible under any cell that manages to develop.

- A backdoor cold front Wednesday will bring gusty northeast winds behind it near the lake and cooler temperatures. This front will also bring chances for showers and storms (around 20 to 40 percent) Wednesday afternoon, with the better chances in south central to southwestern Wisconsin. Gusty winds are possible with stronger storms.

- Dry for later this week into the weekend, with above normal temperatures developing.

UPDATE

Issued 727 PM CDT Tue May 26 2026

An outflow boundary pushing southward from the area of storms in east central to north central Wisconsin continues to help develop new storms to the north of the area. Will need to watch this feature and see if it makes it into the far northern parts of the area over the next few hours. If it does, then isolated to scattered storms could occur in an uncapped environment with modest mean layer CAPE around 500 J/kg or more with weak deep layer bulk shear around 15 knots or so. There is enough DCAPE (greater than 500 J/kg) to bring the risk for gusty winds with any stronger storms that develop. They would move slowly east if they were to develop, so brief heavy rainfall may also occur.

An isolated shower or storm may occur overnight in far northwest parts of the area, as the main upward vertical motion shifts to the west of the area, where weak 850 mb confluence/convergence resides. Otherwise, middle to high clouds should move through the area tonight into Wednesday morning.

In addition, the backdoor cold front will move southward across Lake Michigan overnight into Wednesday morning, pushing southwest across the area later in the day. There is some question if this will push into and through the area earlier in the day, with gusty northeast winds behind it bringing in much cooler temperatures. Thus, there is some uncertainty with high temperatures on Wednesday, especially in northern and eastern parts of the area.

The front will also serve as a potential focal point for isolated to perhaps scattered showers and storms by middle afternoon on Wednesday, mainly over south central Wisconsin where more instability will be present. Mean layer CAPE around 500 J/kg with weak capping and deep layer bulk shear around 20 knots or so may bring gusty winds and brief heavy rainfall with any stronger storms. CAMs are still quite uncertain with if and where storms may occur, so kept PoPs in the 20 to 30 percent range for the most part. Highs should reach the middle 80s southwest of the front, with cooler 70s behind it and 60s along the lakeshore.

A moderate to high swim risk is possible later Wednesday into Thursday morning for the Lake Michigan beaches, with increasing north to northeast winds and building waves.

Wood

SHORT TERM

Issued 231 PM CDT Tue May 26 2026

Tonight through Wednesday night:

Convergence boundary has set up across northern Wisconsin, draping into southeastern Minnesota. This will serve as the focal point for convective development this afternoon. Shear under 15 kt surface to 500 mb will mean decaying storms will produce any propagating motion. With plenty of solar heating at the surface, and at least marginal moisture return, expecting SBCAPE to rise to around 1000 J/kg in central to southwestern Wisconsin this afternoon. DCAPE around 1000 J/kg will allow for gusty winds under any thunderstorms that do develop. However, this DCAPE does arise from extremely dry mid levels (~800-600 mb) and a lack of strong, consistent forcing will likely prevent storms from developing a strong updraft core and therefore will allow significant evaporation. This indicates that it would be difficult to realize these DCAPE values in central Wisconsin. Therefore, not anticipating any severe thunderstorm winds this evening, but a briefly gusty storm may be possible from Marquette to Sheboygan Counties and perhaps as far south as Sauk County this evening.

Outside of storm development, expecting temperatures in the mid to upper 80s, with the highest temperatures in central to southwestern Wisconsin. An isolated spot or two may see up to 90 degrees. Winds will gradually turn more southerly this afternoon, allowing for a lake breeze to develop and bring temperatures down in the near-lake regions (generally about a half county inland). Winds will then diminish into tonight, becoming light and variable to light and northerly into Wednesday.

Late Wednesday morning through Wednesday afternoon, a backdoor cold front will sweep through Lake Michigan into southern Wisconsin. In southeastern Wisconsin, expecting the front to pass through during the morning hours, with minimal instability development, so no storms are currently expected. Farther inland, as the frontal feature modifies and slows, this may create a focal point for isolated to scattered storms. 12Z CAMs have backed off on convective development, so have accordingly backed off PoPs into the isolated (~20-30% coverage) category for the afternoon to early overnight hours Wednesday in south-central to southwestern Wisconsin. Dry air in the mid levels continues, but a slightly deeper 70% RH layer in the low levels may allow for a few more storms than today, and an isolated strong to severe storm may be possible with winds as the primary threat. High temperatures in the 70s are expected near Lake Michigan with highs in the mid to upper 80s inland. If the front moves through faster/earlier in the day, expect lower high temperatures.

Overnight, expect continued northeast winds and temperatures falling into the low 50s across the area. Any lingering showers and storms will taper off from east to west.

MH

LONG TERM

Issued 231 PM CDT Tue May 26 2026

Thursday through Tuesday:

High pressure settles in behind the backdoor cold front on Thursday, with light northwesterly winds keeping temperatures in the 60s near Lake Michigan, low 70s along the Kettle Moraine, and around 80 degrees in southwest Wisconsin. Dry conditions continue overnight, with clear skies and calm winds bringing lows in the 40s. Friday, high pressure lingers, allowing for plenty of sunshine to bring temperatures in the 80s away from Lake Michigan, and an afternoon lake breeze to keep Lake Michigan Counties in the 70s.

A weaker backdoor cold front on Saturday will bring cooler conditions to the region, with highs in the 70s in southeastern Wisconsin and the low 80s in southwestern Wisconsin. Sunday, northeast winds continue, with highs in the 70s to low 80s, once again with the coolest conditions near Lake Michigan. High pressure remains in place through early next week, with lake breezes impacting temperatures near the Lake and largely dry conditions persisting.

MH

AVIATION

Issued 727 PM CDT Tue May 26 2026

An outflow boundary pushing southward from the area of storms in east central to north central Wisconsin continues to help develop new storms to the north of the area. Will need to watch this feature and see if it makes it into the far northern parts of the area over the next few hours, especially toward the Sheboygan terminal.

If it does, then isolated to scattered storms could occur. Gusty winds may occur with any stronger storms that develop. An isolated shower or storm may occur overnight in far northwest parts of the area. Otherwise, middle to high clouds should move through the area tonight into Wednesday morning, with VFR category conditions expected.

In addition, the backdoor cold front will move southward across Lake Michigan overnight into Wednesday morning including the terminals near the lake, pushing southwest across the rest of the area later in the day. There is some question if this will push into and through the area earlier in the day. Gusty northeast winds are expected to develop right behind the front and linger into Wednesday night and perhaps Thursday morning.

The front will also serve as a potential focal point for isolated to perhaps scattered showers and storms by middle afternoon on Wednesday, mainly over south central Wisconsin where more instability will be present. Gusty winds are possible with any stronger storms. Otherwise, scattered middle level clouds around 7000 feet AGL are expected during the day, with VFR category conditions outside of any storms.

Wood

MARINE

Issued 727 PM CDT Tue May 26 2026

Low pressure around 29.5 inches will exit into Quebec, keeping southerly gusty winds through this evening, before a backdoor cold front pushes southwestward late tonight into Wednesday morning and shifts winds northeasterly. Gusts up to 30 knots are possible along this front. Winds remain northeasterly through Thursday, gradually diminishing into Thursday night as high pressure around 30.3 inches builds into the Great Lakes region.

A Small Craft Advisory may be needed for Wednesday night into Thursday morning for the nearshore waters, for gusty northeast winds and building waves.

Lighter and variable winds are expected through Thursday night, before a brief period of southwesterly winds moves in as weak low pressure system moves through Ontario into the Northeast. On Saturday, an additional backdoor cold front will allow for brisk northeasterly winds once again. Winds then weaken and remain light and predominantly northerly through early next week under high pressure.

MH/Wood

MKX WATCHES/WARNINGS/ADVISORIES

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