NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 060944
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
444 AM CDT Mon Apr 6 2026

.KEY MESSAGES...

- Scattered pop-up/convective snow showers are expected this
  afternoon and evening over east central Wisconsin, with a
  small chance further southwest and south. Some late
  afternoon/evening commute impacts may occur, caused by sharp
  visibility drops. Some freezing of wet surfaces may occur
  tonight as temperatures drop.

- A mix of light rain and light snow may occur Tuesday night
  (40 to 60 percent chances), with a little light freezing rain
  mixed in as well. Best chances for this would be toward
  Wisconsin Dells and Montello.

- Active pattern continues Wednesday into next weekend, with
  multiple additional periods of rain and a few thunderstorms.

&&

.UPDATE...
Issued 444 AM CDT Mon Apr 6 2026

We will remain in a sheared cyclonic flow pattern through
tonight. However, we have some interesting dynamics going on
over WI today. A mid level shortwave trough will swing across
Ontario and Lake Superior midday. Meanwhile, a little area of
light precip that is associated with an area of isentropic lift
and some weak wave induced by the flow over the Rockies will
track from SD to central IA today.

Southern WI will be caught in an increasing pressure gradient
and therefore breezy northwest winds. Steep low level lapse
rates and shallow, trapped, low level moisture will give us a
chance(15 to 25%) of light rain/snow showers over central WI
(clipping our northern counties from Wisconsin Dells to West
Bend) beginning around midday. Snow showers associated with
this feature are currently over northwest Wisconsin and are on
track to reach central WI around 10 AM. The bulk of these
showers should be primarily over northern and central
WI, as upstream trends and model soundings suggest that the
moisture may be too shallow for widespread precip down in
southern WI, but diurnally steepening lapse rates may help.

That Lake Superior wave will initiate a stronger cold front to
track down Lake Michigan this afternoon and evening. This is
the main feature to watch for scattered, blustery snow showers
from late afternoon through mid evening (2 PM to 8 PM) over
east central and southeast WI. Expect brief drops in visibility
to a mile or less in these snow bursts with blustery winds.
Travelers during the afternoon/evening commute should exercise
caution. While a brief dusting of snow is possible during the
showers, it will quickly melt due to the warm pavement temps in
between the showers. Shower activity will diminish overnight as
the front drops into IL. Temps will drop into the lower 20s
overnight, so any wet surfaces could freeze and become slick.
The good news is that it will be breezy so pavement should dry
quickly.

Cronce

&&

.SHORT TERM...
Issued 1225 AM CDT Mon Apr 6 2026

Today through Thursday:

Any rain showers should exit the area to the southeast over the
next hour or so. There may be some partial clearing that occurs
overnight, before the next area of clouds moves into the area
from the north. Northwest winds should develop overnight and
gradually pick up by dawn. They will become gusty during the
morning hours and linger through the afternoon.

There continues to be increasing potential for pop-
up/convective snow showers this afternoon and evening, mainly
toward east central Wisconsin and possibly affecting areas east
of Interstate 41 and south toward Milwaukee. There is decent
upward vertical motion from more differential CVA aloft, with
low level frontogenesis response with the cold front passing
southward through Lake Michigan and eastern parts of the area.

Forecast soundings are showing steep low level lapse rates with
perhaps up to around 100 J/kg of mean layer CAPE toward the
Sheboygan area, with lower instability values to the southwest.
HREF continues to show potential for at least scattered
convective snow showers with snowfall rates of one half inch
per hour (perhaps up to one inch per hour with the
instability), which seems reasonable given the setup. There
should also be mild ground temperatures that drop quickly Monday
evening, so there may be some refreezing of wet roads.

This does not seem to be a classic snow squall setup at this
time, but certainly a good setup for these convective snow
showers. They may reduce visibility to 1 to 2 miles or less in
a short amount of time, with the snow rates and gusty winds.
Any accumulations may be tough to come by on the warmer roads,
but may see wet, slushy accumulations under an inch on grassy
surfaces.

Thus, some impacts to the late afternoon/early evening commute
are possible, especially toward east central Wisconsin. Will
continue to monitor this potential and message accordingly.

High pressure should bring quiet weather Tuesday, with continued
cool temperatures in the lower 40s. Onshore winds near the
lake will keep highs in the 30s there.

There remains a 40 to 60 percent chance for light rain and light
snow mix Tuesday night, with some light freezing rain possibly
mixing in. Forecast soundings continue to show this potential,
as warm air advection on gusty south winds helps bring a
gradually warmer layer of air in the low levels but above the
surface. It may be more of a transition from light snow to a
wintry mix to light rain Tuesday night, with mainly light rain
Wednesday morning. The best chances for this will be toward
Wisconsin Dells and Montello. Will continue to monitor this
potential.

The gusty south winds should bring warmer highs into the 60s
inland, with perhaps 50s closer to the lake with south southeast
winds developing. A cold frontal boundary sagging into the area
from the northwest Wednesday night into Thursday should bring
continued rounds of showers with a few storms possible at
times. Better chances look to be Wednesday night (60 to 80
percent chances), with 30 to 40 percent chances lingering
Thursday.

Another mild day Thursday with highs into the 60s are
anticipated with gusty southwest winds. Temperature confidence
is relatively high, as ensembles are showing small spreads in
the forecast ranges of temperatures Wednesday into Thursday.

Wood

&&

.LONG TERM...
Issued 1225 AM CDT Mon Apr 6 2026

Thursday night through Sunday:

Ensembles remain in some disagreement with the progression of
the frontal boundary across and south of the area Thursday night
into Saturday. Some take the front to the south of the area
later Friday into Saturday, keeping the area generally dry.
Others stall it out across southeast and far southern parts of
the area, with continued chances for showers and a few
thunderstorms at times. For now, will maintain at least 20 to 30
percent chance for showers and a few thunderstorms at times
Thursday night into Saturday, until more clarity on the frontal
boundary location can be seen.

Temperature spreads in the ensembles are relatively small
during this period, considering the uncertainty with the frontal
boundary. They generally point to mild temperatures, with highs
well into the 50s and lows in the middle to upper 30s. Cooler
values near the lake may occur if winds become onshore.

Ensemble means are generally showing south to southwest flow
and warm air advection at the surface later in the weekend, with
possible warming temperatures into the 70s by Sunday. Spreads
in the temperatures are still fairly low, with most ensemble
members showing the warmer trend. Chances (generally 40 to 50
percent or more) for showers and a few storms may linger at
times into Sunday, with the warmer and more moist airmass moving
into the region.

Wood

&&

.AVIATION...
Issued 444 AM CDT Mon Apr 6 2026

Areas of lower clouds with VFR bases continue to track through
southern WI early this morning. Expect more widespread low
clouds with some MVFR to VFR bases around 2500 to 3500 ft to
move into portions of south central WI mid morning and southeast
WI by midday. Expect an uptick in the northwest winds at this
time. Scattered light rain/snow showers are possible over
central and east central WI from late morning through mid
afternoon.

Late in the afternoon, expect a cold front to drop down Lake
Michigan. This is the feature that should bring scattered to
numerous snow showers to east central and southeast WI between
23Z/6PM and 02Z/9PM. Brief reductions in visibility down to a
quarter mile or less and MVFR ceilings are possible within these
showers. KSBM, KMKE and KUES have these showers included in the
TAFs, and there is less certainty for the showers to reach
KENW. Gusty northerly winds are expected with the showers and
then winds will diminish quickly tonight as temps fall into the
lower 20s.

Cronce

&&

.MARINE...
Issued 444 AM CDT Mon Apr 6 2026

Northwest winds will increase today as a small area of low
pressure around 30.0 inches develops east of Lake Huron. A few
gale force gusts are possible over the northern half of the open
waters during the afternoon hours.

Winds will decrease tonight into Tuesday as high pressure around
30.5 inches moves over and east of the area. Some moderate
freezing spray is possible over the northern half of the lake
this evening.

Low pressure around 29.6 inches will form over the northern Great
Plains and approach Lake Michigan Tuesday night into Wednesday,
resulting in increasing southerly winds across the waters. Winds
will remain gusty into Wednesday night as the low passes north of
Lake Superior. Gale force gusts will be possible with this
system.

Winds will taper during the day Thursday, with high pressure
around 30.4 inches moving from the northern Plains toward Lake
Superior. Showers and a few thunderstorms are forecast Wednesday
into Thursday.

Northwest winds are expected to increase around midday, so
moved the start time of the Small Craft Advisory up to 18Z/1PM
CDT today.

Cronce

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646...1 PM
     Monday to 7 AM Tuesday.

&&

$$

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