NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 031155 AAA
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
555 AM CST Tue Mar 3 2026

.KEY MESSAGES...

- Area of light drizzle and light freezing drizzle will continue
  to shift east across southern portions of the area early this
  morning. They are weakening as they encounter dry air to the
  east, but slick spots may still occur in areas at or below
  freezing.

- Temperatures are trending well above normal through the end
  of the week.

- Additional periods of rain are forecast Wednesday night into
  Thursday (about 40 to 70 percent chances) and Friday into
  Saturday (80-plus percent chances). Some thunderstorms are
  possible in each round of rain.

&&

.UPDATE...
Issued 555 AM CST Tue Mar 3 2026

The area of light drizzle and light freezing drizzle will
continue to shift east across southern portions of the area
early this morning, as 700 mb frontogenesis response works with
some moisture in the 850 mb to 700 mb layer. There is still some
dry air below 850 mb, which appear to be helping to weaken this
area as it shifts east. Will continue to keep this in the
forecast until middle morning, when temperatures rise above
freezing and the frontogenesis response shifts east of the area.
There still may be some slick spots that occur in areas at or
below freezing, as well as elevated and untreated surfaces, for
the next few hours.

Low clouds may move north into southern portions of the area for
a time this morning, before retreating southward this afternoon.
Highs should reach into the middle 40s inland, with highs around
40 near the lake.

Clearing should push into the area this evening, as weak high
pressure develops over the area. Patchy fog is possible in
northern parts of the area later tonight into early Wednesday
morning. As temperatures drop below freezing, may see some
slick spots develop in low lying areas with the fog/freezing
fog. Lows should drop into the middle to upper 20s tonight.

Wood

&&

.SHORT TERM...
Issued 1159 PM CST Mon Mar 2 2026

Tonight through Thursday:

Synopsis/Mesoanalysis: High pressure is centered off the Northeast
coast late this evening, with an affiliated surface ridge entrenched
across the majority of the state. Evident in regional radar, a
narrow area of light rain is ongoing over northern Iowa. Said
rainfall is being driven by an area of upper divergence &
accompanying warm advection & frontogenesis in the 850-700 mb layer.
The precip will attempt to work east-southeast into the area late
tonight/early Tuesday morning as its affiliated forcing mechanisms
move toward southern Lake Michigan. How far east the precipitation
reaches remains uncertain given lingering low level dry air
affiliated with the aforementioned surface ridge, though locations
generally along and south of a Wisconsin Dells - Waupun - Port
Washington line standing the best chances of seeing light
precipitation during the 3-9 AM time frame. Some light freezing rain
is possible at the onset of precipitation, particularly from Monroe -
Madison - Wisconsin Dells and points east. A light glaze of ice
can't be ruled out on untreated surfaces in any locations
experiencing light freezing rain, though any icing will be quick to
melt as temperatures rise following sunrise. Budget a few extra
minutes of time if planning to be on the roads early Tuesday
morning. Precip will quickly wrap up by late Tuesday morning, with
dry conditions continuing through most of the day Wednesday. The
next disturbance will slowly move in Wednesday night through
Thursday, bringing the next chances for rain & perhaps a few
thunderstorms to southern Wisconsin.

Late Tonight into Tuesday morning: Will be closely monitoring
incoming precip as it attempts to work into the area. Low level dry
air will prove to be a limiting factor on precip reaching the
surface, particularly outside of the narrow zone of enhanced lift
being provided by upper divergence & 850-700 mb warm advection and
frontogenesis. Expect that said forcing mechanisms will remain south
of a Wisconsin Dells - Waupun - Port Washington line. Have updated
precip probabilities to account for ongoing radar trends, with areas
in the southwest corner of the CWA having the greatest potential of
seeing light precipitation. Have maintained mentionable but lower
precip probabilities moving east of I-39, where the influences of
dry air could become an even bigger limiting factor on the eastward
progress of precip. Due to periods of clear skies through the first
half of the evening, surface temps have become cool enough to
support some initial freezing rain or freezing drizzle along & east
of a Monroe - Madison - Wisconsin Dells line. Thus can't rule out
some very light icing of untreated surfaces in these locations in
the event precip reaches the ground. Continue to expect that any
related impacts would remain below Special Weather Statement/Winter
Weather Advisory thresholds, but will nevertheless be monitoring
trends through the predawn hours.

Tuesday night into Wednesday morning: Will be monitoring for some
patchy fog/frost potential with skies clearing out and surface winds
remaining light. Given a very shallow near-surface moist layer,
could see more frost than fog, but can nevertheless rule out some
visibility reductions in some spots. Have thus inserted mentions in
the evening forecast update. Will need to monitor temperature trends
in the event fog becomes more favored, as sub-freezing surface
temperatures would lead to some patchy freezing fog & slick spot
potential on untreated surfaces.

Wednesday evening into Thursday: The next disturbance will gradually
move in, leading to increasing rain chances across the region.
Global deterministic & ensemble guidance is beginning to converge on
a disturbance track across the southeastern half of the area, which
is translating to likely precip probabilities southeast of a Monroe-
Madison-Sheboygan line with chance probabilities further northwest.
Do continue to see some weak instability in LREF forecasts, so a few
embedded thunderstorms remain possible with rain occurring during
the late Wednesday - Thursday time frame. Not expecting any
strong/severe hazards, though some cloud to ground lightning and
brief heavy downpours would be possible in any embedded
thunderstorms. Anticipate measurable rainfall accumulations, with
probabilistic guidance indicating ~40-70% chances of 0.25" or
greater over the southeast half of the area with lighter totals
further northwest.

Quigley

&&

.LONG TERM...
Issued 1159 PM CST Mon Mar 2 2026

Thursday night through Monday:

Weak shortwave ridging will briefly take hold Thu nt in the wake of
the shortwave trough. Stratus clouds will likely linger and cannot
rule out patchy drizzle.

An upper low over the Intermountain West Thu nt will then eject newd
as an open shortwave trough to the Mid MO River VAlley or srn MN by
12Z Sat. The sfc low will track into the same region by 00Z Sat with
a warm front extending ewd along the WI and IL border.
The GEFS is more amplified with this low pressure area than the Ens
ECMWF, but both are expected to bring sufficient warm, moist
advection and lift for widespread rain (80-90 percent) Fri afternoon
and night. The sfc warm front will pass nwd Fri nt while low
pressure tracks through wrn and nrn WI, likely reaching Ontario Sat
AM. The cold front will then pass on Sat, likely in the morning.
Overall the timing and evolution of this system could change to some
degree, but a mild and wet period is still likely. High temps in the
50s and 60s are forecast.

Afterward an active quasi-zonal polar jet stream over srn Canada
will then result in strong low pressure tracking ewd across far nrn
Ontario on Sunday. This will support dry swly winds and warm
advection over srn WI with continued mild temps. A dry cold front
will then pass Sun nt with high pressure for Mon.

Gehring

&&

.AVIATION...
Issued 555 AM CST Tue Mar 3 2026

The area of light drizzle and light freezing drizzle will
continue to shift east across southern portions of the area
early this morning. There is still some dry air in the low
levels, which appear to be helping to weaken this area as it
shifts east. Will continue to have light drizzle mentioned at
most terminals until 15Z, with PROB30 mentions for light
freezing drizzle. There still may be some slick spots that
occur in areas at or below freezing for the next few hours.

Low clouds with ceilings dropping to 1500 to 2500 feet AGL
should move north into southern portions of the area for a time
this morning, before retreating southward this afternoon. Light
east to southeast winds should become north to northeast by
later this afternoon.

Clearing should push into the area this evening, as weak high
pressure develops over the area with light winds. Patchy fog is
possible in northern parts of the area later tonight into early
Wednesday morning. As temperatures drop below freezing, may see
some slick spots develop in low lying areas with the
fog/freezing fog, but will keep mention out of terminals for
now. Winds should become east to southeast on Wednesday, with
mostly sunny skies.

Wood

&&

.MARINE...
Issued 1159 PM CST Mon Mar 2 2026

1000 mb low pressure is centered over the Hudson Bay this evening,
with 1040 mb high pressure positioned off the coast of the
northeastern United States. Placement of the two surface features is
resulting in generally south to southeasterly breezes across the
open waters of Lake Michigan. Winds will lighten from the second
half of the overnight through Tuesday morning as a small area of
1022 mb high pressure attempts to develop over the western Great
Lakes. An upper disturbance is forecast to cross southern Lake
Michigan late tonight into Tuesday morning, bringing chances for
light rain or freezing rain to the southern half of Lake Michigan.

Light south to southwesterly winds will continue across the northern
half of Lake Michigan through Wednesday, while winds shift out of
the east further south in response to developing 1012 mb low
pressure in the middle Mississippi River Valley. Said low will
likely pass just to the south of Lake Michigan Wednesday night into
Thursday, allowing for northeast winds to become established across
the entirety of the open waters. Rain showers will spread north
across the open waters in response to the approaching/passing low
Wednesday afternoon through Thursday. A few thunderstorms are
possible over southern Lake Michigan Wednesday afternoon & evening.
Severe weather is not anticipated.

1000 mb low pressure remains forecast to develop in the central
Great Plains Thursday night, and is expected to be somewhere between
the Upper Mississippi River Valley & northern Wisconsin by Friday
evening. Said low will move near or just north of northern Lake
Michigan Friday night into Saturday morning, quickly moving into
Quebec by Saturday evening. South to southwest winds will thus
steadily increase ahead of the developing & approaching low Friday
afternoon into Saturday morning, ultimately veering westerly
Saturday afternoon. Winds will be gusty at times during the Friday-
Saturday time frame, with a few gales possible Friday night into
Saturday morning. It remains uncertain if any gales would be
widespread enough to warrant headlines. Widespread rain and embedded
thunderstorms will accompany the approaching/passing low Friday
through Saturday, with strong or severe storms not anticipated at
this time.

Isolated to widely scattered thunderstorms are possible in nearshore
zones ahead of approaching/passing low pressure systems Wednesday
afternoon & evening, and once again Friday into Saturday. Not
currently expecting widespread strong or severe storms in either
round of activity. Winds & waves will approach Small Craft Advisory
thresholds Friday night through Saturday morning, with trends being
monitored for possible headlines in later forecasts.

Quigley

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...None.
&&

$$

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