NWS-Milwaukee/Sullivan Forecast Discussion

						FXUS63 KMKX 270027 AAA
AFDMKX

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
727 PM CDT Tue May 26 2026

.KEY MESSAGES...

- An isolated storm or two (around a 20 percent chance) is
  possible across far northern and northwestern parts of the
  area this evening, with gusty winds possible under any cell
  that manages to develop.

- A backdoor cold front Wednesday will bring gusty northeast
  winds behind it near the lake and cooler temperatures. This
  front will also bring chances for showers and storms (around
  20 to 40 percent) Wednesday afternoon, with the better chances
  in south central to southwestern Wisconsin. Gusty winds are
  possible with stronger storms.

- Dry for later this week into the weekend, with above normal
  temperatures developing.

&&

.UPDATE...
Issued 727 PM CDT Tue May 26 2026

An outflow boundary pushing southward from the area of storms in
east central to north central Wisconsin continues to help
develop new storms to the north of the area. Will need to watch
this feature and see if it makes it into the far northern parts
of the area over the next few hours. If it does, then isolated
to scattered storms could occur in an uncapped environment with
modest mean layer CAPE around 500 J/kg or more with weak deep
layer bulk shear around 15 knots or so. There is enough DCAPE
(greater than 500 J/kg) to bring the risk for gusty winds with
any stronger storms that develop. They would move slowly east if
they were to develop, so brief heavy rainfall may also occur.

An isolated shower or storm may occur overnight in far northwest
parts of the area, as the main upward vertical motion shifts to
the west of the area, where weak 850 mb confluence/convergence
resides. Otherwise, middle to high clouds should move through
the area tonight into Wednesday morning.

In addition, the backdoor cold front will move southward across
Lake Michigan overnight into Wednesday morning, pushing
southwest across the area later in the day. There is some
question if this will push into and through the area earlier in
the day, with gusty northeast winds behind it bringing in much
cooler temperatures. Thus, there is some uncertainty with high
temperatures on Wednesday, especially in northern and eastern
parts of the area.

The front will also serve as a potential focal point for
isolated to perhaps scattered showers and storms by middle
afternoon on Wednesday, mainly over south central Wisconsin
where more instability will be present. Mean layer CAPE around
500 J/kg with weak capping and deep layer bulk shear around 20
knots or so may bring gusty winds and brief heavy rainfall with
any stronger storms. CAMs are still quite uncertain with if and
where storms may occur, so kept PoPs in the 20 to 30 percent
range for the most part. Highs should reach the middle 80s
southwest of the front, with cooler 70s behind it and 60s along
the lakeshore.

A moderate to high swim risk is possible later Wednesday into
Thursday morning for the Lake Michigan beaches, with increasing
north to northeast winds and building waves.

Wood

&&

.SHORT TERM...
Issued 231 PM CDT Tue May 26 2026

Tonight through Wednesday night:

Convergence boundary has set up across northern Wisconsin, draping
into southeastern Minnesota. This will serve as the focal point
for convective development this afternoon. Shear under 15 kt
surface to 500 mb will mean decaying storms will produce any
propagating motion. With plenty of solar heating at the surface,
and at least marginal moisture return, expecting SBCAPE to rise to
around 1000 J/kg in central to southwestern Wisconsin this
afternoon. DCAPE around 1000 J/kg will allow for gusty winds
under any thunderstorms that do develop. However, this DCAPE does
arise from extremely dry mid levels (~800-600 mb) and a lack of
strong, consistent forcing will likely prevent storms from
developing a strong updraft core and therefore will allow
significant evaporation. This indicates that it would be difficult
to realize these DCAPE values in central Wisconsin. Therefore, not
anticipating any severe thunderstorm winds this evening, but a
briefly gusty storm may be possible from Marquette to Sheboygan
Counties and perhaps as far south as Sauk County this evening.

Outside of storm development, expecting temperatures in the mid to
upper 80s, with the highest temperatures in central to
southwestern Wisconsin. An isolated spot or two may see up to 90
degrees. Winds will gradually turn more southerly this afternoon,
allowing for a lake breeze to develop and bring temperatures down
in the near-lake regions (generally about a half county inland).
Winds will then diminish into tonight, becoming light and variable
to light and northerly into Wednesday.

Late Wednesday morning through Wednesday afternoon, a backdoor
cold front will sweep through Lake Michigan into southern
Wisconsin. In southeastern Wisconsin, expecting the front to pass
through during the morning hours, with minimal instability
development, so no storms are currently expected. Farther inland,
as the frontal feature modifies and slows, this may create a focal
point for isolated to scattered storms. 12Z CAMs have backed off
on convective development, so have accordingly backed off PoPs
into the isolated (~20-30% coverage) category for the afternoon to
early overnight hours Wednesday in south-central to southwestern
Wisconsin. Dry air in the mid levels continues, but a slightly
deeper 70% RH layer in the low levels may allow for a few more
storms than today, and an isolated strong to severe storm may be
possible with winds as the primary threat. High temperatures in
the 70s are expected near Lake Michigan with highs in the mid to
upper 80s inland. If the front moves through faster/earlier in the
day, expect lower high temperatures.

Overnight, expect continued northeast winds and temperatures
falling into the low 50s across the area. Any lingering showers
and storms will taper off from east to west.

MH

&&

.LONG TERM...
Issued 231 PM CDT Tue May 26 2026

Thursday through Tuesday:

High pressure settles in behind the backdoor cold front on
Thursday, with light northwesterly winds keeping temperatures in
the 60s near Lake Michigan, low 70s along the Kettle Moraine,
and around 80 degrees in southwest Wisconsin. Dry conditions
continue overnight, with clear skies and calm winds bringing
lows in the 40s. Friday, high pressure lingers, allowing for
plenty of sunshine to bring temperatures in the 80s away from
Lake Michigan, and an afternoon lake breeze to keep Lake
Michigan Counties in the 70s.

A weaker backdoor cold front on Saturday will bring cooler
conditions to the region, with highs in the 70s in southeastern
Wisconsin and the low 80s in southwestern Wisconsin. Sunday,
northeast winds continue, with highs in the 70s to low 80s, once
again with the coolest conditions near Lake Michigan. High
pressure remains in place through early next week, with lake
breezes impacting temperatures near the Lake and largely dry
conditions persisting.

MH

&&

.AVIATION...
Issued 727 PM CDT Tue May 26 2026

An outflow boundary pushing southward from the area of storms
in east central to north central Wisconsin continues to help
develop new storms to the north of the area. Will need to watch
this feature and see if it makes it into the far northern parts
of the area over the next few hours, especially toward the
Sheboygan terminal.

If it does, then isolated to scattered storms could occur.
Gusty winds may occur with any stronger storms that develop. An
isolated shower or storm may occur overnight in far northwest
parts of the area. Otherwise, middle to high clouds should move
through the area tonight into Wednesday morning, with VFR
category conditions expected.

In addition, the backdoor cold front will move southward across
Lake Michigan overnight into Wednesday morning including the
terminals near the lake, pushing southwest across the rest of
the area later in the day. There is some question if this will
push into and through the area earlier in the day. Gusty
northeast winds are expected to develop right behind the front
and linger into Wednesday night and perhaps Thursday morning.

The front will also serve as a potential focal point for
isolated to perhaps scattered showers and storms by middle
afternoon on Wednesday, mainly over south central Wisconsin
where more instability will be present. Gusty winds are possible
with any stronger storms. Otherwise, scattered middle level
clouds around 7000 feet AGL are expected during the day, with
VFR category conditions outside of any storms.

Wood

&&

.MARINE...
Issued 727 PM CDT Tue May 26 2026

Low pressure around 29.5 inches will exit into Quebec, keeping
southerly gusty winds through this evening, before a backdoor
cold front pushes southwestward late tonight into Wednesday
morning and shifts winds northeasterly. Gusts up to 30 knots
are possible along this front. Winds remain northeasterly
through Thursday, gradually diminishing into Thursday night as
high pressure around 30.3 inches builds into the Great Lakes
region.

A Small Craft Advisory may be needed for Wednesday night into
Thursday morning for the nearshore waters, for gusty northeast
winds and building waves.

Lighter and variable winds are expected through Thursday night,
before a brief period of southwesterly winds moves in as weak
low pressure system moves through Ontario into the Northeast. On
Saturday, an additional backdoor cold front will allow for
brisk northeasterly winds once again. Winds then weaken and
remain light and predominantly northerly through early next
week under high pressure.

MH/Wood

&&

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

$$

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