NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 050001
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
601 PM CST Wed Mar 4 2026

.KEY MESSAGES...

- Light rain or drizzle are possible (30 to 50 percent) late
  Wed night from Madison to Milwaukee and south. Light to
  moderate rain (60 to 80 percent) is expected Thursday morning
  over much of southern Wisconsin.

- Moderate to brief heavy rainfall rates are possible Friday
  into Friday night, with embedded thunderstorms expected. A few
  strong to potentially severe storms may be possible Friday
  night.

- Very mild Friday and again early next week.

&&

.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.

&&

$$

Visit us at weather.gov/milwaukee

Follow us on Facebook, X, and YouTube at:
www.facebook.com/NWSMilwaukee
www.x.com/NWSMilwaukee
www.youtube.com/NWSMilwaukee