textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Scattered snow showers are expected into linger into this evening over far eastern Wisconsin, shifting southward across areas near the lake. Brief visibility drops may occur into early evening. Some freezing of wet surfaces may occur tonight, as temperatures drop below freezing.

- A mix of light rain and light snow is forecast Tuesday night (30 to 60 percent chances), with a little light freezing rain mixed in over south central Wisconsin. Any ice accumulation will be very minor and likely only on elevated surfaces.

- Milder temperatures then return on Wednesday, with widespread showers (60-80 percent) forecast Wednesday night during the passage of a cold front.

- Another round of widespread showers and storms may occur Thursday night, followed by an active weather pattern of more showers and storms late in the weekend into next week possible.

UPDATE

Issued 706 PM CDT Mon Apr 6 2026

Scattered snow showers will linger into this evening over northeastern parts of the forecast area, shifting southward across areas near the lake. This should occur as the backdoor cold front moves quickly south over the waters and is slower to advance on land, which will bring convergence and help support the scattered snow shower activity.

Most of this activity has been fairly light in nature, with the heavier snow showers remaining over the lake. There may be a heavier snow shower that develops into early evening, which could briefly reduce visibility to 2 miles or less. However, expecting most of this activity to be light in nature, with the gusty winds keeping the snow from accumulating on surfaces.

This activity should end by middle to late evening, with temperatures quickly dropping with cold air advection. This may bring freezing to any surfaces that get wet from the snow showers, though this is not expected to be impactful.

Clouds are expected to clear overnight into early Tuesday morning. Gusty north winds into this evening should gradually weaken overnight and become northeast to east on Tuesday, as high pressure moves across the region. Lows tonight should drop into the upper teens to lower 20s, with highs Tuesday in the lower 40s well inland and middle 30s closer to the lakeshore.

Wood

SHORT TERM

Issued 155 PM CDT Mon Apr 6 2026

This afternoon through Wednesday night:

The shortwave trough from nrn Ontario to Lake Superior will continue sewd tnt, while its associated wave of low pressure over the nrn Great Lakes tracks to the lower Great Lakes. The instability showers will continue over east central WI this afternoon. A backdoor cold front will then shift from Lake MI into far ern WI this evening. There may be enough low level convergence for linear development of light snow moving inland. Just as lake to 850 mb temp differences become favorably for lake effect snow by late evening, drier air arrives and hinders any development. Any snow accum that would occur will be very light and likely just on the grass and elevated surfaces. Continued cold advection of a polar airmass and clearing skies will then drop temps in the upper teens to lower 20s by 12Z Tue.

Polar high pressure then tracks from central WI to the lower Great Lakes on Tue, while 500 mb height rises occur. Mostly sunny skies are expected, but a polar airmass will only rebound into the lower to middle 40s well inland from the lake. Ely winds will only allow high temps in the 30s for far ern WI.

Modest sely winds and low to mid level warm advection will begin Tue nt ahead of a well organized upper trough and sfc low moving along the Canadian border in the Great Plains. This will bring chances (20-50 percent) for mixed pcpn over srn WI, highest over south central WI. A period of freezing rain may occur over south central WI during this time, while any glazing of ice would likely remain on elevated surfaces. Breezy sly winds will then boost temps into the 60s well away from Lake MI on Wed. Continued chances (20-50 percent) for light rain are still forecast on Wed with highest chances north and west of Madison.

Rain chances will then rise to 60-80 percent Wed nt with the passage of the cold front trailing from the low moving across nrn Ontario. A swly low level jet of 60 kts will bring a good surge of thetae advection just ahead of the front. Rainfall totals of 0.20-0.50 inches are possible.

Gehring

LONG TERM

Issued 232 PM CDT Mon Apr 6 2026

Thursday through Monday:

Thursday through Friday Night: Wet conditions continue as a surface front crosses southern Wisconsin & lingers near the Wisconsin- Illinois state line. Current guidance suggests that the most-favored period for precipitation will be Thursday night into Friday morning, when an upper disturbance will cross the western Great Lakes & interact with the front. Temperatures should be mild enough for all rain, with an embedded thunderstorm or two possible if enough elevated instability can build in overhead. Not expecting any strong/severe storms at this time, but will continue to watch trends. Will, however, need to monitor where any embedded thunderstorms set up, as any enhanced rainfall rates could act to exacerbate already elevated river levels if they track over basins heavily impacted by prior precip. Northerly winds will lead to cooler afternoon highs on Friday after milder conditions on Thursday.

Saturday through Monday: Despite increasing deterministic uncertainty regarding smaller-scale evolutions, global ensembles are in reasonably good agreement for a synoptic scale pattern shift across the CONUS. Pronounced mid-upper level ridging will build into the Mid-Atlantic from the Gulf of Mexico while a broad upper trough digs into the Great Basin vicinity. Occurring in response to the pattern shift, winds will trend southwesterly through the column, allowing a warm air mass to build into the western Great Lakes from the Great Plains. Temperatures will thus trend upward during this portion of the period, with highs climbing into the 70s Sunday into Monday. The warmer air will be accompanied by increasing low level moisture, with dew points pushing the 60 degree mark from Sunday into Monday. Despite remaining uncertainties regarding smaller-scale features, placement of the western trough will place southern Wisconsin in line for additional shortwave passages. This will translate to continued active conditions into early next week, with building warmth and humidity supporting even greater potential for thunderstorms. Will need to monitor this time frame for both strong storms & hydro impacts given the increasing instability & already high river levels, though it remains too early to offer specific details. Will continue to watch trends and discuss with greater detail as this portion of the period draws closer.

Quigley

AVIATION

Issued 706 PM CDT Mon Apr 6 2026

Scattered snow showers will linger into this evening over northeastern parts of the forecast area, shifting southward across areas near the lake. This should occur as a cold front moves quickly south over the waters and is slower to advance on land.

Most of this activity has been fairly light in nature, with the heavier snow showers remaining over the lake. There may be a heavier snow shower that develops into early evening, which could briefly reduce visibility to 2 miles or less. However, expecting most of this activity to be light in nature, with visibility generally at 6 miles or higher and ceilings around or above 3500 feet AGL. The gusty northwest to north winds will keep the snow from accumulating on surfaces.

This activity should end by middle to late evening, with temperatures quickly dropping. This may bring freezing to any surfaces that get wet from the snow showers, though this is not expected to be impactful.

Ceilings above 3500 feet AGL are expected to clear overnight into early Tuesday morning. Gusty north winds into this evening should gradually weaken overnight and become northeast to east on Tuesday, as high pressure moves across the region.

Wood

MARINE

Issued 706 PM CDT Mon Apr 6 2026

Northwest gales have generally subsided over the northern portions of the lake, and the Gale Warning has been allowed to expire. Some moderate freezing spray is possible over the northern half of the lake into this evening.

Winds will decrease late tonight into Tuesday, as high pressure around 30.5 inches moves across central Lake Michigan Tuesday morning into the early afternoon.

Low pressure around 29.5 inches will then track along the Canadian border Tuesday night and Wednesday, then track north of Lake Superior Wednesday night into Thursday morning. This will result in breezy south winds which may increase to gale force. Much weaker winds will then take hold by Thursday afternoon and the remainder of the week.

A Small Craft Advisory will remain in effect from Sheboygan to Winthrop Harbor through tonight, for gusty nwly winds becoming northerly and high waves.

Gehring/Wood

MKX WATCHES/WARNINGS/ADVISORIES

WI...None. LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646 until 7 AM Tuesday.