textproduct: Milwaukee/Sullivan

KEY MESSAGES

- Scattered snow showers are expected into early this evening over far eastern WI. Some late afternoon/evening commute impacts may occur, caused by sharp visibility drops. 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 WI. 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.

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 155 PM CDT Mon Apr 6 2026

Areas of MVFR Cigs will continue this afternoon and evening especially over ern WI where scattered snow showers will be present. Vsbys could briefly drop to 1-2SM with the snow showers. Afterward, VFR conditions are expected through Tue.

Gehring

MARINE

Issued 155 PM CDT Mon Apr 6 2026

Northwest gales are expected over the north half of the lake this afternoon and early evening, as low pressure around 29.7 inches tracks across the northern Great Lakes, reaching the lower Great Lakes late tonight. A Gale Warning is now in effect. Some moderate freezing spray is possible over the northern half of the lake 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 this afternoon through tonight for gusty nwly winds becoming northerly and high waves.

Gehring

MKX WATCHES/WARNINGS/ADVISORIES

WI...None. LM...Gale Warning...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565 until 7 PM Monday.

Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646 until 7 AM Tuesday.