textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Increasing potential for pop-up/convective snow showers this afternoon and evening, especially over east central Wisconsin. Some late afternoon/evening commute impacts may occur, caused by sharp visibility drops and light slushy accumulations on roadways. Some freezing of wet surfaces may occur tonight as temperatures drop.

- A mix of light rain and light snow may occur Tuesday night (40 to 60 percent chances), with a little light freezing rain mixed in as well. Best chances for this would be toward Wisconsin Dells and Montello.

- Active pattern continues Wednesday into next weekend, with multiple additional periods of rain and a few thunderstorms.

SHORT TERM

Issued 1225 AM CDT Mon Apr 6 2026

Today through Thursday:

Any rain showers should exit the area to the southeast over the next hour or so. There may be some partial clearing that occurs overnight, before the next area of clouds moves into the area from the north. Northwest winds should develop overnight and gradually pick up by dawn. They will become gusty during the morning hours and linger through the afternoon.

There continues to be increasing potential for pop- up/convective snow showers this afternoon and evening, mainly toward east central Wisconsin and possibly affecting areas east of Interstate 41 and south toward Milwaukee. There is decent upward vertical motion from more differential CVA aloft, with low level frontogenesis response with the cold front passing southward through Lake Michigan and eastern parts of the area.

Forecast soundings are showing steep low level lapse rates with perhaps up to around 100 J/kg of mean layer CAPE toward the Sheboygan area, with lower instability values to the southwest. HREF continues to show potential for at least scattered convective snow showers with snowfall rates of one half inch per hour (perhaps up to one inch per hour with the instability), which seems reasonable given the setup. There should also be mild ground temperatures that drop quickly Monday evening, so there may be some refreezing of wet roads.

This does not seem to be a classic snow squall setup at this time, but certainly a good setup for these convective snow showers. They may reduce visibility to 1 to 2 miles or less in a short amount of time, with the snow rates and gusty winds. Any accumulations may be tough to come by on the warmer roads, but may see wet, slushy accumulations under an inch on grassy surfaces.

Thus, some impacts to the late afternoon/early evening commute are possible, especially toward east central Wisconsin. Will continue to monitor this potential and message accordingly.

High pressure should bring quiet weather Tuesday, with continued cool temperatures in the lower 40s. Onshore winds near the lake will keep highs in the 30s there.

There remains a 40 to 60 percent chance for light rain and light snow mix Tuesday night, with some light freezing rain possibly mixing in. Forecast soundings continue to show this potential, as warm air advection on gusty south winds helps bring a gradually warmer layer of air in the low levels but above the surface. It may be more of a transition from light snow to a wintry mix to light rain Tuesday night, with mainly light rain Wednesday morning. The best chances for this will be toward Wisconsin Dells and Montello. Will continue to monitor this potential.

The gusty south winds should bring warmer highs into the 60s inland, with perhaps 50s closer to the lake with south southeast winds developing. A cold frontal boundary sagging into the area from the northwest Wednesday night into Thursday should bring continued rounds of showers with a few storms possible at times. Better chances look to be Wednesday night (60 to 80 percent chances), with 30 to 40 percent chances lingering Thursday.

Another mild day Thursday with highs into the 60s are anticipated with gusty southwest winds. Temperature confidence is relatively high, as ensembles are showing small spreads in the forecast ranges of temperatures Wednesday into Thursday.

Wood

LONG TERM

Issued 1225 AM CDT Mon Apr 6 2026

Thursday night through Sunday:

Ensembles remain in some disagreement with the progression of the frontal boundary across and south of the area Thursday night into Saturday. Some take the front to the south of the area later Friday into Saturday, keeping the area generally dry. Others stall it out across southeast and far southern parts of the area, with continued chances for showers and a few thunderstorms at times. For now, will maintain at least 20 to 30 percent chance for showers and a few thunderstorms at times Thursday night into Saturday, until more clarity on the frontal boundary location can be seen.

Temperature spreads in the ensembles are relatively small during this period, considering the uncertainty with the frontal boundary. They generally point to mild temperatures, with highs well into the 50s and lows in the middle to upper 30s. Cooler values near the lake may occur if winds become onshore.

Ensemble means are generally showing south to southwest flow and warm air advection at the surface later in the weekend, with possible warming temperatures into the 70s by Sunday. Spreads in the temperatures are still fairly low, with most ensemble members showing the warmer trend. Chances (generally 40 to 50 percent or more) for showers and a few storms may linger at times into Sunday, with the warmer and more moist airmass moving into the region.

Wood

AVIATION

Issued 1225 AM CDT Mon Apr 6 2026

Any rain showers should exit the area to the southeast over the next hour or so. There may be some partial clearing that occurs overnight, before the next area of ceilings around 3500 feet AGL moves into the area from the north. They should remain around 3500 feet AGL through the day and evening. Northwest winds should develop overnight and gradually pick up by dawn. They will become gusty during the morning hours and linger through the afternoon.

There continues to be potential for pop-up snow showers this afternoon and evening, mainly toward the Sheboygan terminal and possibly affecting Waukesha and Milwaukee terminals by late afternoon/early evening. Snow showers with snowfall rates up to one half to one inch inch per hour are possible with the gusty northwest winds.

May see visibility drop quickly to 1 to 2 miles or less at times, with ceilings varying between 2500 and 3500 feet AGL. There should also be mild ground temperatures that drop quickly Monday evening, with some quick refreezing potential. May see wet, slushy accumulations under an inch mainly on grassy areas toward the Sheboygan terminal if these persist.

Winds will become north tonight and weaken, with ceilings gradually shifting out of the area.

Wood

MARINE

Issued 1225 AM CDT Mon Apr 6 2026

Northwest winds will linger overnight, as high pressure around 30.7 inches builds into the northern Plains. These winds will increase once more during the day Monday, as a small area of low pressure around 30.0 inches develops east of Lake Huron. A few gale force gusts are possible over the northern half of the open waters during the afternoon hours.

Winds will decrease Monday night into Tuesday, as high pressure around 30.5 inches moves over and east of the area. Some moderate freezing spray is possible over the northern half of the lake Monday evening.

A Small Craft Advisory is in effect for later this afternoon and tonight for the nearshore waters, for increasing northwest winds and building waves.

Low pressure around 29.6 inches will form over the northern Great Plains and approach Lake Michigan Tuesday night into Wednesday, resulting in increasing southerly winds across the waters. Winds will remain gusty into Wednesday night, as the low passes north of Lake Superior. Gale force gusts will be possible with this system.

A Small Craft Advisory will likely be needed for the Wednesday into Wednesday night period for the nearshore waters, with a few gale force gusts possible.

Winds will taper during the day Thursday, with high pressure around 30.4 inches moving from the northern Plains toward Lake Superior. Showers and a few thunderstorms are forecast Wednesday into Thursday.

Wood

MKX WATCHES/WARNINGS/ADVISORIES

WI...None. LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646...4 PM Monday to 7 AM Tuesday.