NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 070006 AAA
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
706 PM CDT Mon Apr 6 2026

.KEY MESSAGES...

- Scattered snow showers are expected into linger into this
  evening over far eastern Wisconsin, shifting southward across
  areas near the lake. Brief visibility drops may occur into
  early evening. 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 Wisconsin. 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.

&&

.UPDATE...
Issued 706 PM CDT Mon Apr 6 2026

Scattered snow showers will linger into this evening over
northeastern parts of the forecast area, shifting southward
across areas near the lake. This should occur as the backdoor
cold front moves quickly south over the waters and is slower to
advance on land, which will bring convergence and help support
the scattered snow shower activity.

Most of this activity has been fairly light in nature, with the
heavier snow showers remaining over the lake. There may be a
heavier snow shower that develops into early evening, which
could briefly reduce visibility to 2 miles or less. However,
expecting most of this activity to be light in nature, with the
gusty winds keeping the snow from accumulating on surfaces.

This activity should end by middle to late evening, with
temperatures quickly dropping with cold air advection. This may
bring freezing to any surfaces that get wet from the snow
showers, though this is not expected to be impactful.

Clouds are expected to clear overnight into early Tuesday
morning. Gusty north winds into this evening should gradually
weaken overnight and become northeast to east on Tuesday, as
high pressure moves across the region. Lows tonight should drop
into the upper teens to lower 20s, with highs Tuesday in the
lower 40s well inland and middle 30s closer to the lakeshore.

Wood

&&

.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 706 PM CDT Mon Apr 6 2026

Scattered snow showers will linger into this evening over
northeastern parts of the forecast area, shifting southward
across areas near the lake. This should occur as a cold front
moves quickly south over the waters and is slower to advance on
land.

Most of this activity has been fairly light in nature, with the
heavier snow showers remaining over the lake. There may be a
heavier snow shower that develops into early evening, which
could briefly reduce visibility to 2 miles or less. However,
expecting most of this activity to be light in nature, with
visibility generally at 6 miles or higher and ceilings around
or above 3500 feet AGL. The gusty northwest to north winds will
keep the snow from accumulating on surfaces.

This activity should end by middle to late evening, with
temperatures quickly dropping. This may bring freezing to any
surfaces that get wet from the snow showers, though this is not
expected to be impactful.

Ceilings above 3500 feet AGL are expected to clear overnight
into early Tuesday morning. Gusty north winds into this evening
should gradually weaken overnight and become northeast to east
on Tuesday, as high pressure moves across the region.

Wood

&&

.MARINE...
Issued 706 PM CDT Mon Apr 6 2026

Northwest gales have generally subsided over the northern
portions of the lake, and the Gale Warning has been allowed to
expire. Some moderate freezing spray is possible over the
northern half of the lake into 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 through tonight, for gusty nwly winds becoming
northerly and high waves.

Gehring/Wood

&&

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

&&

$$

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