025
FXUS63 KMKX 251139
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
639 AM CDT Sat Jul 25 2026

.KEY MESSAGES...

- Isolated thunderstorms may occur this afternoon and tonight
  across the far northwest.

- There is a Moderate Swim Risk later this afternoon and this
  evening for the Lake Michigan beaches in Sheboygan County.
  Breaking waves and currents are expected. Stay away from
  dangerous areas like piers, breakwalls, and river outlets.

- Warmer and more humid conditions will bring chances for
  thunderstorms at times into Monday evening.

- There is the potential for severe storms mainly Sunday
  afternoon into Monday evening, though timing and placement of
  storms are still uncertain.

- Hot and humid conditions Sunday and Monday are likely, and a
  Heat Advisory may eventually be needed for this period.

&&

.UPDATE...
Issued 630 AM CDT Sat Jul 25 2026

Winds are shifting southwesterly regionally along the back side
of departing high pressure early this morning. The change in
wind direction is allowing deeper moisture to spread into the
western Great Lakes. Leading edge of the deeper moisture return
is marked by low stratus clouds currently working into areas
along and west of I-39. Will see these clouds continue to spread
east through the rest of the area this morning, along with
steadily increasing dew points. Presence of these clouds into
the afternoon may hold temps a touch cooler than initially
forecast, so have knocked temperatures back a few degrees
through this afternoon. Even with the slightly cooler temps,
conditions will begin to feel sticky for most by late afternoon
today.

Currently well north of the region, will be monitoring the
southward progress of a cold frontal boundary through the day
today. Forecast guidance suggests that this boundary---which
currently extends from the southern Hudson Bay to the
International Falls, MN vicinity---will continue to steadily
drop south toward north-central Wisconsin by late afternoon.
Could see isolated to widely scattered thunderstorm development
along the front as it impinges upon deeper moisture arriving
from the Plains. In all likelihood, any such development would
likely remain to the north of the area/in close proximity to the
surface front, struggling to make it into southern Wisconsin
prior to sunset & the onset of boundary layer stabilization.
Nevertheless, there are a couple more southern solutions in the
guidance suite, so have added some 15% PoPs across far northern
areas to account for the low end chance that an isolated storm
reaches southern Wisconsin. In the event a storm did make it, it
would have the potential of being severe with damaging winds and
large hail. A level 1/5 marginal risk for severe weather thus
continues across northwestern areas into this evening given this
potential. Will be providing additional updates through today as
trends clarify.

After the isolated evening storm potential, attention then turns
westward through tonight as the low level jet increases over the
Northern Plains and the Canadian Prairies. While mesoscale
models & CAMs depict a wide range of possible geographic
placements, there is general consensus that areas of convection
will blossom within the increasing low level jet axis. Some
solutions suggest that upscale growth into one or more complexes
is possible in the aforementioned development, which would be a
plausible progression given the wind shear that will be in place
regionally. Where precisely any thunderstorm complexes
materialize, and how far east they can make into the Upper
Mississippi Valley/western Great Lakes approaching daybreak
Sunday morning, remain sources of considerable forecast
uncertainty at this juncture. As these uncertainties begin to
clarify, so will some of the uncertainties surrounding Sunday`s
severe weather potential. Will be closely evaluating the
upcoming 12Z CAM suite & reflecting any emerging trends in the
afternoon update.

Quigley

&&

.SHORT TERM...
Issued 108 AM CDT Sat Jul 25 2026

Today through Monday Night:

Warm air and moisture advection will help drive an area of
low clouds into the area into this morning, covering most of
south central Wisconsin and perhaps into southeast Wisconsin as
well. These low clouds should gradually scatter out during the
afternoon, though if they hang on they will hold down high
temperatures today. For now, will maintain highs in the middle
80s, with dew points climbing through the 60s bringing more
humid conditions. Will need to watch the low clouds and see if
they will mix out this afternoon.

There may be a period for small chances (around 20 percent) for
an elevated thunderstorm to move southeast into areas north of
Madison and Milwaukee this afternoon and tonight. This would be
within the warm air advection and likely lifted from 850 mb or
higher. If a storm were to develop, gusty winds and hail may
occur with elevated tall skinny CAPE and increasing deep layer
bulk shear.

However, the airmass over the area should be fairly well capped
for mixed layer parcels, so anything that occurs would have to
move southeast into the area. For now, will leave the 20 percent
chances going in the far northern areas. Most of the area
should remain dry.

South southwest winds are expected today. Any lake breeze in
the afternoon is likely to remain near the shoreline, with south
winds providing onshore flow near Port Washington and northward
to Sheboygan.

There is a Moderate Swim Risk later this afternoon into early
this evening for the Lake Michigan beaches in Sheboygan County.
Waves of 2 to 3 feet are expected from south winds. Breaking
waves and currents are expected. Stay away from dangerous areas
like piers, breakwalls, and river outlets.

There are better chances for thunderstorms at times mainly
Sunday afternoon into Monday evening, as the area remains within
northwest flow aloft and some warm air advection lingers in the
low levels Sunday and Sunday night. A frontal boundary may
develop and become quasi-stationary to the north of the area
Sunday into Monday, which may help drive showers and storms
there.

The low level jet nose may also try to point into southern
Minnesota and west central Wisconsin later tonight into Sunday
morning and try to develop showers and storms, which may try to
shift southeast toward the area. There will still be a fairly
decent cap in place over southern Wisconsin, though forecast
soundings are trying to erode it more so than 24 hours ago.
Still, there is a lack of good upward vertical motion to focus
convection over the area, so anything will probably have to
shift southeast into the area Sunday into Sunday night.
Uncertainty remains fairly high at this time with timing and
placement of possible storms.

If storms can move into the area, damaging winds and large hail
are possible, given large mean layer CAPE over 3000 J/kg and
increasing deep layer bulk shear values of 35 to 45 knots. Will
message the severe potential as well as the uncertainty in
timing and placement of storms.

Monday into Monday evening remains the best chances for severe
storms to occur, as the forecast soundings are mixing out most
of the cap in place with strong mean layer CAPE and deep layer
bulk shear values remaining. There may be a 500 mb vorticity
maximum that passes just northeast of the area later Monday into
Monday evening, with a surface low possibly allowing for an MCS
to develop in northern Wisconsin and shift south southeast
through parts of the area. A lot of Monday into Monday evening
severe chances will hinge on what happens Sunday into Sunday
night, with any outflow or other boundaries that may move into
the area. Uncertainty remains high, so will message this as well
into Monday evening.

Hot and humid conditions are likely Sunday into Monday, with
highs into the lower 90s, and dew points in the lower to middle
70s, allowing heat index values into the 97 to 104 degree range
over most of the area. Thus, a Heat Advisory may eventually be
needed for the area during this period.

Wood

&&

.LONG TERM...
Issued 108 AM CDT Sat Jul 25 2026

Tuesday through Friday:

Northwest flow at 500 mb is generally expected to remain over
the region through the rest of next week, with the ridge axis
perhaps slowly shifting east and flattening out. It appears from
ensembles that high pressure should build into the region for
Tuesday into Wednesday, bringing warm and humid conditions but
keeping dew points and heat index values lower than Sunday and
Monday. More active weather may return to the area later this
week, as low pressure and a cold front tries to shift southeast
through the region. The warm and humid conditions should linger
as well, per ensemble member trends and continued small NBM
temperature spreads.

Wood

&&

.AVIATION...
Issued 630 AM CDT Sat Jul 25 2026

BKN low level clouds will gradually spread east across southern
Wisconsin through this morning, bringing CIGs anywhere between
FL015 and FL035 depending on location. Latest forecast guidance
is suggesting that MVFR CIGs will make it into southeast
Wisconsin by late morning, so have inserted a period of
prevailing MVFR flight categories at UES, MKE and ENW in the 12Z
update. Have held CIGs at FL035 in the vicinity of SBM, as
confidence in prevailing MVFR conditions is lower this far
northeast. Will be monitoring obs trends through this morning &
make amendments to this forecast where necessary. Expect low
stratus to gradually dissipate from late afternoon into the
evening, when VFR flight categories return to all terminals.
There are small chances for isolated TSRA across the far north
this afternoon/evening, with forecast confidence being too low
to justify any mentions in the SBM TAF at this time. Will
continue to monitor for possible changes through today.

Quigley

&&

.MARINE...
Issued 108 AM CDT Sat Jul 25 2026

Gusty south to southwest winds are expected across all of Lake
Michigan into today, as low pressure around 29.5 inches shifts
east across northern Ontario. Gusts up to 30 knots are expected
over the far northern parts of the lake.

A frontal boundary will then stall mainly over Wisconsin and Lake
Michigan tonight through most of Monday. This will result in
increasing thunderstorm chances, with severe storms possible at
times. Very warm and moist air flowing over the relatively cool
waters may cause patchy dense fog Sunday into Monday. South to
southwest winds will remain south of the boundary, with more
variable winds to the north.

Northerly winds are expected Monday night through Wednesday, as
high pressure around 30.0 inches builds over the Upper Great
Lakes. Look for southerly winds and more unsettled weather to
return later in the week.

Wood

&&

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

$$

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