Marine Weather and Tide Forecast for Greendale, WI

UPDATE
Issued 551 PM CST Wed Mar 4 2026

Patchy fog will be possible again tonight as low level moisture remains trapped beneath a strong inversion. Some of that fog may become dense, particularly in southeast Wisconsin. Freezing fog appears to be less of a concern tonight as overnight lows over much of the area are expected to remain above freezing.

CMiller

SHORT TERM
Issued 155 PM CST Wed Mar 4 2026

Tonight and Thursday:

High level clouds are streaming in from the southwest while the low level stratus finally starts to pull out to our south this afternoon. This will give all of southern Wisconsin a window of partly to mostly sunny skies into this evening. This period of clear skies will be short lived as a low pressure system in Missouri tracks northeast into Illinois and then northern Indiana. As this low approaches clouds will return from south to north this evening into tonight. Scattered light rain showers will move in from the south around midnight ahead of the sfc low.
Rain will become more widespread early Thursday morning as the upper level shortwave moves through the Great Lakes Region and the sfc low passes to our south. The better lift and instability will be with the low and frontal boundaries to our south so not expecting much in the way of thunder for southern Wisconsin.
Can't rule out one or two storms producing a rumble of thunder, but that would be mainly for the WI/IL border areas. With rain moving in from the south and then exiting to the east, the northwest corner of our forecast area will likely miss out on the rain through Thursday morning. As the low pull away to the east Thursday, rain may linger along eastern Wisconsin into the early afternoon hours.

Overcast skies will remain through Thursday night as another low pressure system develops in the eastern Rockies and advects toward the Great Lakes Region. As this sfc low tracks northeast, an upper level trough will follow a similar path providing good lift and support for rain and thunderstorms. There is high confidence in getting widespread rain and storms starting Friday morning and continuing into Saturday morning with POPs around 80% or better. An initial push of storms will likely develop along the leading edge of some WAA, then another push of showers/storms along the warm front and again with the cold front Saturday morning. There are likely to be breaks in the rain/storm activity throughout the day with some more scattered convection with the warm front and then likely a line of storms along the cold front.

The exact track of the sfc low is still a bit in question and this will play a big roll in the potential for stronger or severe storms across southern Wisconsin. There are good dynamics with the upper level jet and LLJ, but Wisconsin is lacking in instability with a lot of the models. The dynamics can overcome a lot, but that instability (even a little bit) will be important to keep an eye on. The timing of the warm front will be a big factor in that. The later in the night the warm front passes and the more easterly it is, the more limited storms may be and vice versa. The best timing for any stronger storms looks to be Friday evening into Friday night. There are still a lot of details to hash out here so stay up to date with the forecast.

Patterson

LONG TERM
Issued 155 PM CST Wed Mar 4 2026

Saturday through Thursday:

The cold front will still be moving through southeast WI Saturday morning. The highs for the day will occur early, and the chance for rain will linger until the surface cold front clears the area.
Upper levels will dry out quickly, but low clouds within the wrap- around region will linger over southern WI well into the afternoon, and we cannot rule out a few sprinkles with this feature.

High pressure will briefly take hold of WI as it expands from the Plains. A weak low pressure system crossing Ontario will bring us increasing southwest winds Sunday. This will help push highs back into the upper 50s to around 60. Any light rain associated with this system is expected to remain north of central WI.

The next cold front stemming from the slow-moving Ontario Low will swing across southern WI Monday afternoon or evening, but this will be a pretty diffuse front, meaning not a big temp gradient along it. It may be diffuse enough where there would not be a big wind shift, but models disagree on this.

Models begin to diverge on Tuesday, where the 12Z operational GFS shuns that Mon nt cold front to the south of WI while the ECWMF front stalls over central WI and then quickly shifts back north with the next approaching low from the Plains. The Plains low will track across IL and IN, but how far north it tracks remains uncertain. The latest 12Z GFS and ECMWF Ensembles support their diverging nature of this front. This is stemming from the GFS having a stronger low crossing Lake Superior Friday night.

The precip amounts and types for Tuesday into Wednesday will be dependent upon this track. The next low pressure system to watch will be Thursday night into Friday as it crosses the Northern Plains.

Cronce

AVIATION
Issued 600 PM CST Wed Mar 4 2026

Ceilings are expected to continually lower this evening through tonight as low level moisture works northward into the area.
Expect patchy fog and some potential for drizzle this evening over southeast Wisconsin, with fog linger and rain becoming possible near daybreak on Thursday. Winds are expected to remain light and northeasterly through tomorrow.

CMiller

MARINE
Issued 155 PM CST Wed Mar 4 2026

High pressure around 30.3 inches centered over Lake St. Clair will slowly move east into the New England State this evening.
As this high moves out, low pressure around 29.9 inches in Missouri will move northeast toward northern Indiana/Ohio. Under the influence of the linger high pressure, winds remain light and variable across Lake Michigan. These light and variable winds have resulted in lingering dense fog across portions of southwestern and west central Lake Michigan. This dense fog will likely persist into this evening until a more modest wind flow moves in ahead of the incoming low.

Rain and a few thunderstorms will be possible across the southern half of Lake Michigan tonight through Thursday afternoon as this low pressure system passes to the south. Light to moderate northeast winds will set up across the Lake during this time.

Meanwhile a low pressure system around 29.5 inches will develop in the eastern Rockies and advect toward upper Mississippi Valley by Friday evening. This low will move near or just north of Lake Michigan later Friday night into Saturday morning, quickly moving into Quebec by Saturday evening.

As this low passes to the north, breezy southerly winds will develop for Friday afternoon and night, then shifting northwest on Saturday with the passage of the cold front. Widespread rain and embedded thunderstorms will accompany the approaching and passing low Friday into Friday night. A small craft advisory may be needed during this time for the breezy south winds.

Patterson

MKX WATCHES/WARNINGS/ADVISORIES
WI...None.
LM
Dense Fog Advisory
LMZ644-LMZ645-LMZ646-LMZ671-LMZ673-LMZ675- LMZ777-LMZ779 until 9 AM Thursday.