textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Showers will move through the area this morning (40 to 70 percent chances). A passing cold front this afternoon may bring some thunderstorms (20 to 40 percent chances). Gusty winds and small hail may occur with the strongest storms, if they develop.

- A period of south gales is expected over the middle third of the open waters of Lake Michigan from middle morning to middle afternoon today. A Gale Warning is in effect for this area, as well as for the nearshore waters from Sheboygan to Port Washington.

- Gusty south to southwest winds are expected today. Gusts of 35 to 40 MPH are expected at times. A gust or two to 45 MPH may occur, but most gusts should remain below Wind Advisory levels.

- Relatively warm and humid conditions with increasing storm chances returns Thursday night into the weekend.

UPDATE

Issued 548 AM CDT Tue May 12 2026

An area of showers will move east through the area during the morning hours, within focused warm air advection in the low levels with the low level jet transporting moisture into the region. CAMs suggest that this activity may exit the area by midday, or linger in southeast Wisconsin later this morning into early or perhaps middle afternoon. They vary with how much additional showers and some storms develop from middle to late afternoon across the area with the cold frontal passage.

The main thing to watch will be how long the showers and associated clouds linger into this afternoon, and if we can get any sunshine and instability to develop. If so, there should be enough skinny mean layer CAPE (300 to 600 J/kg) with strong deep layer bulk shear (around 50 knots) for some storms to produce gusty winds and small hail. This would be supported synoptically aloft by an advancing 500 mb shortwave trough into the area. Would need more than 1000 J/kg of mean layer CAPE for severe storms, which seems unlikely at this time. Will need to monitor the mesoscale environment into this afternoon. This should exit to the east by early this evening.

In addition, forecast soundings are showing steep low level lapse rates allowing for robust mixing in the boundary layer today. Gusts of 35 to 40 MPH are expected over most of the area, and there could be a gust or two to 45 MPH. For now, think most gusts will remain below Wind Advisory levels today. Warm temperatures are expected today, with highs into the middle to upper 70s. If more sunshine occurs, it may reach 80 degrees or higher.

Gusty winds will shift west to northwest behind the cold front this evening, with gusty northwest winds later tonight into Wednesday lingering. The cyclonic flow at 500 mb into Wednesday should allow for scattered to broken, or perhaps more overcast, stratocumulus clouds to linger. Cold air advection should bring in cooler but more seasonable temperatures, with highs Wednesday in the lower to middle 60s.

Wood

SHORT TERM

Issued 1106 PM CDT Mon May 11 2026

Today through Wednesday night:

Low pressure will approach from the northeast tonight, dragging a warm front over southern WI around daybreak. WAA on the leading edge of the warm advection will drive showers around dawn and through the morning hours. All of these showers will be elevated with negligible MUCAPE, so thunder is not expected. Shower activity will then grow more scattered heading into the afternoon as the main push of mid level WAA moves east/northeast, with strong surface WAA on gusty southwest winds advecting a warm surface airmass in the mid 70s into southern WI. A cold front is then expected to move through the area during the mid to late afternoon. Shower and storm coverage and strength along the front will be highly contingent upon air mass recovery during the late morning into the mid afternoon. At this time, CAMs depict just enough instability along the front (~400 J/kg CAPE) to drive scattered storm development. However, the skinny nature of the modeled CAPE profiles will limit storm strength and severity. A few rumbles of thunder are most likely with activity along the front, while small hail and gusty winds will remain isolated and only occur with storms that manage to become well established in Far SE WI before moving over Lake Michigan.

Following the cold front, sfc CAA will usher in a cooler air mass for Wednesday. Highs will be in the low to mid 60s amid breezy northwest winds. Light frost may occur Wednesday night into Thursday.

CMiller

LONG TERM

Issued 1144 PM CDT Mon May 11 2026

Thursday through Tuesday:

A gradual warming trend will take hold on Thursday as upper level ridging from the Plains leans east into the Great Lakes region. Highs are projected to rise into the 80s on Saturday. The warming will be spurred on by multiple waves of WAA, most notably Thursday night into Friday, then Saturday into Sunday. With these waves of WAA, expected shower and storm chances and modest increases in humidity. Beyond, models vary a bit regarding how showers and storms will evolve along a passing cold front on Sunday and how much rain will linger into Monday, with the ECMWF favoring a drier solution, while the GFS favors storms Sunday night and lingering showers Monday. In either case, warmth sticks around for the end of the extended period.

CMiller

AVIATION

Issued 548 AM CDT Tue May 12 2026

An area of showers will move east through the area during the morning hours, with mainly VFR conditions expected. This activity may exit the area by midday, or linger in southeast Wisconsin later this morning into early or perhaps middle afternoon. There is uncertainty with how much additional showers and some storms develop from middle to late afternoon across the area with the cold frontal passage.

The main thing to watch will be how long the showers and associated VFR clouds linger into this afternoon, and if we can get any sunshine and instability to develop. If so, some storms may develop and produce gusty winds and small hail. Less development would occur with less sunshine. This activity should exit to the east by early this evening.

There may be brief low level wind shear conditions for the next few hours, until surface winds pick up, but will keep out of TAFs for now due to borderline conditions.

Gusty south to southwest winds are expected today, with gusts of 30 to 35 knots at times. There could be a gust or two to 40 knots. Gusty winds will shift west to northwest behind the cold front this evening, with gusty northwest winds later tonight into Wednesday. Scattered to broken, or perhaps more overcast, stratocumulus clouds around 3500 to 4000 feet AGL should linger as well.

Wood

MARINE

Issued 548 AM CDT Tue May 12 2026

Winds will become south southeast early this morning and quickly become south and gusty through the morning hours, as low pressure around 29.6 inches approaches from the northwest.

Despite the cold lake surface temperatures, showers over the lake will mix down gales from middle morning through middle afternoon. A Gale Warning is in effect for this time period, over roughly the middle third of the lake, as well as for the nearshore waters from Sheboygan to Port Washington. Building waves are expected today into this evening.

Gusty winds then ease a bit during the early evening hours, as a cold front passes and winds become northwesterly. Gusty northwest winds then return later tonight into Wednesday. A Small Craft Advisory is in effect today into Wednesday for the nearshore waters of Lake Michigan. Building waves are expected today into this evening in this area.

North to northwest winds then ease Wednesday night into Thursday, as high pressure around 30.1 inches moves over Lake Michigan. South to southwest winds should then become gusty Friday into Saturday. A Small Craft Advisory may be needed for the nearshore waters during this period.

CMiller/Wood

MKX WATCHES/WARNINGS/ADVISORIES

WI...None. LM...Gale Warning...LMZ364-LMZ366-LMZ563-LMZ565-LMZ567-LMZ643- LMZ669-LMZ671-LMZ868-LMZ870-LMZ872...9 AM Tuesday to 5 PM Tuesday.

Small Craft Advisory...LMZ643...5 PM Tuesday to 4 PM Wednesday.

Small Craft Advisory...LMZ644-LMZ645-LMZ646...9 AM Tuesday to 4 PM Wednesday.