NWS Milwaukee Forecast Discussion
049
FXUS63 KMKX 252103
AFDMKX
Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
403 PM CDT Sat Jul 25 2026
.KEY MESSAGES...
- There is a Moderate Swim Risk afternoon and 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.
- Hot and humid conditions Sunday and Monday are likely. A Heat
Advisory is in effect from noon to 9 PM CDT Sunday. Additional
Heat Advisories may be needed Monday.
- A line of storms may impact southwestern Wisconsin early
Sunday morning. An isolated severe storm may produce damaging
wind with this activity.
- Isolated to scattered storms may develop Sunday afternoon and
evening. Large hail and damaging winds would be possible with
this activity. Sunday night, a line of storms with damaging
winds and hail is expected to develop and progress
southeastward.
- Monday, a cold front will bring final chances for storms to
southern Wisconsin. All hazards are possible with this
activity, but confidence in exact timing and placement remains
dependent on Sunday night storms.
&&
.SHORT TERM...
Issued 404 PM CDT Sat Jul 25 2026
Tonight through Sunday night:
With low stratus continuing to cap the environment, not
expecting any storm development this afternoon and evening.
Temperatures will continue to climb as southwesterly winds bring
in a warm, moist airmass with dewpoints in the 70s. Expect
cloudy conditions and highs in the low 80s.
Overnight tonight, a complex of storms may develop (15-25%
chance) along the nose of the 850 mb LLJ in northern Iowa,
progressing southeastward into southwestern Wisconsin into the
early morning hours Sunday. If this complex develops and
maintains intensity, damaging winds and lightning would be the
main threats, primarily west of the Madison metro. Some rain may
linger into Sunday morning, but is not expected to be
impactful.
Skies clear into Sunday midday, with temperatures quickly rising
to near 90 degrees across southern Wisconsin under continued
southwesterly winds. Areas along Lake Michigan itself may see a
south-southeasterly lake breeze, keeping temperatures in the
low 80s. However, confidence is high in most areas seeing heat
index values of 100-103 degrees, and a Heat Advisory has been
issued for noon to 9 PM CDT on Sunday for all counties away from
Ozaukee and Sheboygan.
Sunday afternoon, mesoscale modeling is indicating potential for
storms to develop along the convergent zone at the northern edge
of the upper level ridging. These storms would progress quickly
southward through Lake Michigan, potentially impacting Lake
Michigan counties (30-40% chance) during the evening hours with
high winds, hail, and an isolated tornado possible. These
storms will quickly progress southward. Meanwhile, any outflow
boundaries from the main complex may produce isolated to
scattered storms inland across the remainder of southern
Wisconsin. These storms would have the primary hazards of hail
and damaging winds, but confidence in inland development is
quite low (15-25%). Environment is primed (0-6 km bulk shear ~35
kt, CAPE 3000-4000 J/kg, PWATs 1.5-1.75 inch), but capping does
remain in place. If a storm can develop through the cap, it will
be severe. The main question is trigger.
Regardless of Sunday afternoon and evening development,
expecting LLJ to nose into western Wisconsin overnight Sunday,
bringing the next chances for severe development to the area.
Global models remain consistent with MCS development over
northern to central Wisconsin, progressing southeastward late
overnight Sunday into Monday morning. These storms would be
capable of producing damaging winds as the main threat with
plenty of MUCAPE (~2500 J/kg) and PWATs around 1.75 inches
becoming common across the region. Bulk shear remains low right
at 30-35 kt, so tornado threat looks to be minimal. These storms
will push into northern Illinois into Monday morning.
MH
&&
.LONG TERM...
Issued 404 PM CDT Sat Jul 25 2026
Monday through Saturday:
Showers with isolated embedded lightning may linger into Monday.
How long these showers linger and therefore where the effective
boundary sets up will be what sets the stage for the next round
of potential severe storms Monday afternoon/evening. Provided
clouds clear efficiently into the afternoon hours, an additional
Heat Advisory may be needed Monday afternoon for heat index
values in the low 100s and temperatures in the upper 80s to low
90s once again, as well as enhanced humidity (dewpoints in the
70s advecting in as well as any additional moisture from storms
Sunday night/Monday morning). Depending on the westward extent
of cloud cover, may only need portions of southwestern Wisconsin
under a Heat Advisory, and conditions will continue to be
evaluated as the event draws closer.
Monday evening, a shortwave ejects from Canada, riding over the
ridging that remains across the Upper Midwest and attaching
itself to any boundary lingering from the morning convection.
Expecting CAPE values to recover quickly into the 2000 to 3000
J/kg range after cloud cover exits, and for shear to increase to
40-45 kt ahead of the shortwave/effective cold front. Severe
storms once again become possible as the shortwave moves through
the region, but will depend largely on precursory conditions.
Therefore, confidence is rising in timing, but impacts remain in
question.
Monday night, storms finally exit to the east and northwesterly
winds develop, bringing in cooler and drier air with lows in the
mid 60s. Tuesday, expect northerly winds to continue as high
pressure builds in, continuing to reduce the humidity but
keeping highs in the mid-80s away from Lake Michigan (lake
breeze influence). Dry conditions under high pressure linger
through at least Wednesday, but high pressure begins to break
down Thursday night into Friday ahead of low pressure ejecting
from the northern Plains.
Next chances for storms develop Thursday night through Friday
as warm frontogenesis builds across the Upper Midwest and low
pressure makes its closest approach. Precipitation chances
diminish into next weekend as high pressure centered over
northern Ontario begins to build back southward.
MH
&&
.AVIATION...
Issued 404 PM CDT Sat Jul 25 2026
Ceilings in the 1500-2500 ft range will slowly scatter out into
this evening, with conditions returning to VFR tonight. Patchy
fog will develop in southwestern to south-central Wisconsin
late tonight, bringing visibilities down to MVFR for JVL and
MSN through sunrise. An isolated storm is possible for
southwestern Wisconsin tonight, but currently is expected to
remain west of MSN. Sunday, VFR conditions are expected to
dominate. During the afternoon to evening hours, a line of
storms may move southward along Lake Michigan with damaging
winds and an isolated tornado. Currently a 20-30% chance of
seeing these storms progress inland. Isolated storms (15-20%
chance) are possible during the afternoon inland of the line,
but are expected to be transient.
MH
&&
.MARINE...
Issued 404 PM CDT Sat Jul 25 2026
A weak low pressure trough around 29.8 inches will stall along the
Wisconsin-Upper Michigan border this evening. It will remain over
Wisconsin and Lake Michigan through most of Monday which will
result in increasing thunderstorm chances with severe storms
possible. Very warm, moist and unstable air flowing over the
relatively cool waters may cause patchy dense fog over the lake
through Monday as well.
Northerly winds will develop Monday night through Wednesday as
high pressure around 29.9 inches builds over the Upper Great Lakes
and the front pushes southward. A few gale force gusts are
possible Tuesday afternoon. Look for southerly winds and more
unsettled weather to resume Thursday into next weekend.
Cronce
&&
.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Heat Advisory...WIZ046-WIZ047-WIZ051-WIZ056-WIZ057-WIZ058-
WIZ059-WIZ062-WIZ063-WIZ064-WIZ065-WIZ066-WIZ067-WIZ068-
WIZ069-WIZ070-WIZ071-WIZ072...noon Sunday to 9 PM Sunday.
LM...None.
&&
$$
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