Severe Thunderstorm Warning 175, NWS Milwaukee, WI

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
509 AM CDT Wed Jul 1 2026

.KEY MESSAGES...

- An Extreme Heat Warning remains in effect for all of southern
  Wisconsin through early this evening. Additional heat
  headlines may be needed into the rest of the week, but some
  uncertainty remains due to clouds and rain chances.

- Isolated to scattered thunderstorms will progress
  northeastward into this morning, mainly north of a Lone Rock
  to Sheboygan line. A stronger storm may produce hail, gusty
  winds and locally heavy rainfall.

- There is a small chance (20 percent) of a thunderstorm this
  afternoon northwest of Madison. A strong to severe storm with
  strong winds and hail would be possible, if it develops.

- There are increasing chances (40 to 70 percent) for
  thunderstorms later this afternoon and tonight, with the
  better chances north of a Lone Rock to Sheboygan line. Some
  strong to severe storms with heavy rainfall may occur at
  times, mainly in the evening. Damaging winds and hail are the
  main hazards.

- There are periodic chances (40 to 60 percent) for
  thunderstorms Thursday into the holiday weekend. Some strong
  to severe storms with heavy rainfall may occur at times,
  though confidence remains low with the timing of each round of
  storms. This may impact outdoor holiday activities at times,
  so keep up with the forecast.

&&

.UPDATE...
Issued 510 AM CDT Wed Jul 1 2026

Storms have developed along the WI/IA border this morning, and
are progressing northeastward into central Wisconsin. SBCAPE
1500-2000 J/kg in place combined with 0-6 km shear right around
35 kt will allow for sustained updrafts and isolated severe
potential from the Wisconsin River Valley to Port Washington
northward this morning. DCAPE values quite high (1100-1300 J/kg)
with high precipitable water values (2 inches) indicate
potential for wet microbursts, with isolated hail up to 1 inch
in diameter also possible.

MH

&&

.SHORT TERM...
Issued 146 AM CDT Wed Jul 1 2026

Today through Friday night:

The Extreme Heat Warning will remain in effect until early this
evening. An extension or a Heat Advisory issuance into later in
the week may eventually be needed, depending on how many clouds
and showers/storms occur. Will likely wait on how clouds and
possible shower/storm trends play out overnight into later today
before making further decisions on the heat headlines for the
rest of the week. Heat index values in the 90s to low 100s are
forecast for Thursday and Friday.

There is a chance (20 to 40 percent) for showers and storms
developing into this morning, before pushing northeastward by
midday. The southwesterly low level jet will be the key feature
to watch, as it develops more of a nose and shifts northeastward
toward the area.

CAMs seem to be favoring scattered showers and storms developing
in southeast Minnesota into southwest Wisconsin by 09Z or so,
shifting northeast into the morning hours. Given the setup with
the southwesterly flow through a deep layer focused from Iowa
into southwest and central Wisconsin, would expect any showers
and storms that develop with the low level jet nose to push
northeast and ride the ridge through these areas.

There is a decent amount of elevated CAPE (1500 to 2500 J/kg),
with weaker deep layer bulk shear around 20 knots increasing to
30 to 35 knots in the morning. Thus, any stronger storm could
produce hail, gusty winds and locally heavy rainfall, given the
very moist airmass in place and storms possibly moving over the
same areas.

There could be an isolated storm that develops this afternoon
northwest of Madison, closer to the low level jet axis. It would
be elevated in nature, but given the high CAPE over 3000 J/kg and
30 to 35 knots of deep layer bulk shear, could see a strong to
severe storm occur.

CAMs suggest clusters of thunderstorms may develop along a
surface boundary in north central Iowa to north central and
northwest Wisconsin by early evening, then shifts east
northeast with the aid of the low level jet toward and into the
northern portions of the area during the evening and overnight.
There is enough mean layer CAPE and deep layer bulk shear for
more strong to severe storm potential, with damaging winds and
hail the main hazards. Heavy rainfall may occur as well.

The low level jet should focus more into southern Wisconsin
Thursday, with a surface boundary in the form of a stationary
front developing as well. These features may help to focus more
showers and thunderstorms at times Thursday into Thursday night,
as well as into Friday. There remains a strong to severe storm
risk with heavy rainfall as well for this period, as high CAPE
and moderate deep layer bulk shear values persist. Details on
this potential will be more clear once the convection into
tonight shows its hand.

Wood

&&

.LONG TERM...
Issued 146 AM CDT Wed Jul 1 2026

Saturday through Tuesday:

Active conditions continue into the holiday weekend, with
multiple batches of thunderstorms expected Saturday through
Sunday.

Subtropical ridging will gradually break down over the eastern
CONUS this weekend, allowing for modestly cooler temperatures
and heat indices. A slow-moving surface boundary will
concurrently slide into southern Wisconsin, supporting daily
chances for showers and thunderstorms both Saturday and Sunday.
Overall storm chances are greatest (50 to 60 percent or more)
on Saturday, when a shortwave trough is progged to move across
southern Wisconsin.

Most favored locations for storms on Sunday will depend on
where the surface boundary sets up in the wake of Saturday's
storms, with boundary location remaining a source of uncertainty
at this time. Will continue to monitor trends over coming
forecasts.

Any weekend storms will be capable of producing cloud-to-ground
lightning and heavy downpours, with a few strong to severe
storms possible. Continue to monitor the forecast is planning to
be outdoors. Widespread precipitation chances wane moving into
the beginning of next week, as broad high pressure builds over
the western Great Lakes.

Saturday/Fourth of July looks to be a potentially active
Independence Day, as an upper shortwave and surface boundary
move across the region. Aforementioned features will be
impinging upon a still unseasonably moist airmass, which will
be supportive of abundant instability. While modest, initial
forecast soundings suggest bulk shear values supportive of at
least loosely-organized convection, so will need to monitor for
some severe weather potential over coming forecasts.

Storms will also be capable of producing heavy downpours given
precipitable water values in the 1.60 to 1.80 inch or greater
range. Regardless of severity, any convection will be capable of
producing cloud-to-ground lightning, which will be hazardous to
anybody attending outdoor holiday festivities. Keep up with the
forecast if planning to be outside Saturday.

Depending on the surface boundary's location in the wake of
Saturday's storms, could see another batch of convection during
the afternoon/evening hours on Sunday. Have maintained 20 to 40
percent precip probabilities from the NBM in the evening
forecast update, given lingering uncertainties related to
surface boundary positioning.

Expect that values will continue to fluctuate with the modeled
positioning of the boundary over coming forecasts, with more
refined locations of favored storm development emerging during
the Friday to Saturday time period. Like Saturday's
thunderstorms, will need to monitor for a few severe storms with
heavy downpours, in addition to lightning potential in all
thunderstorms, in any Sunday activity.

Quigley

&&

.AVIATION...
Issued 510 AM CDT Wed Jul 1 2026

VFR conditions expected for the majority of today, with
scattered deck near 4000 ft. Isolated storms moving
northeastward through central Wisconsin may produce gusty
erratic winds this morning, but are expected to remain north of
the MSN/MKE corridor. This evening into tonight, storms will
progress southeastward through the area, with isolated severe
storms possible. Winds will become gusty and southwesterly
outside of storms this afternoon, diminishing and becoming
westerly tonight. Severe threat ends after midnight tonight.

MH

&&

.MARINE...
Issued 146 AM CDT Wed Jul 1 2026

Modest to breezy south to southwest winds will prevail into
Thursday, then lighter winds should occur into Friday, as high
pressure around 30.1 inches remains to the southeast of the
Great Lakes, while low pressure around 29.5 inches moves slowly
east across central Manitoba into James Bay.

Chances for thunderstorms are forecast across the northern half
of the lake through tonight. There are chances for
thunderstorms across the southern two thirds of the lake
Thursday into Friday evening, and across the southern half of
the lake later Friday night into Sunday. Some strong to severe
storms may occur at times, though confidence remains low with
the timing of each round of storms.

Patchy marine fog will be possible at times, primarily over the
northern half of the lake, as the warm and moist airmass moves
over the lake. There may also be some patchy dense fog along the
Lake Michigan shoreline into this morning.

Southwest winds may approach Small Craft Advisory levels today
into early this evening for the nearshore waters, mainly near
the shoreline.

Wood

&&

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

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Hazardous Weather Outlook
National Weather Service Milwaukee/Sullivan WI
107 AM CDT Wed Jul 1 2026

WIZ046-047-051-052-056>060-062>072-020615-
Marquette-Green Lake-Fond du Lac-Sheboygan-Sauk-Columbia-Dodge-
Washington-Ozaukee-Iowa-Dane-Jefferson-Waukesha-Milwaukee-
Lafayette-Green-Rock-Walworth-Racine-Kenosha-
107 AM CDT Wed Jul 1 2026

This Hazardous Weather Outlook is for portions of east central
Wisconsin, south central Wisconsin and southeast Wisconsin.

.DAY ONE...Today and Tonight

An Extreme Heat Warning remains in effect until early this
evening, for heat index values in the middle to upper 70s
overnight, and up to around 106 degrees later today. Additional
heat headlines may be needed tonight.

There are chances for thunderstorms generally along and north of
a Lone Rock to Sheboygan line into this morning. A stronger storm
may produce hail, gusty winds and locally heavy rainfall.

There is a small chance of a thunderstorm this afternoon northwest
of Madison. A strong to severe storm with strong winds and hail
would be possible, if it develops.

There are increasing chances for thunderstorms later this
afternoon and tonight, with the better chances north of a Lone
Rock to Sheboygan line. Some strong to severe storms with heavy
rainfall may occur at times, mainly in the evening. Damaging winds
and hail are the main hazards.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

Hot and humid conditions with daily maximum heat index values in
the 90s to low 100s are expected into Friday. Additional heat
headlines may be needed, depending on how much cloud cover occurs.

There are periodic chances for thunderstorms Thursday into the
holiday weekend. Some strong to severe storms with heavy rainfall
may occur at times, though confidence remains low with the timing
of each round of storms.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed at times into the weekend.

LMZ643>646-020615-
Sheboygan to Port Washington WI-
Port Washington to North Point Light WI-
North Point Light to Wind Point WI-
Wind Point WI to Winthrop Harbor IL-
107 AM CDT Wed Jul 1 2026

This Hazardous Weather Outlook is for the nearshore waters from
Sheboygan Wisconsin to Winthrop Harbor Illinois.

.DAY ONE...Today and Tonight

Patchy dense fog may occur along the Lake Michigan shoreline into
this morning.

A few thunderstorms are possible into this morning, mainly north
of Port Washington.

Southwest winds will approach Small Craft Advisory levels today.

There are chances for thunderstorms tonight, with the better
chances north of Port Washington. Some strong to severe storms may
occur at times, mainly in the evening. Damaging winds and hail
are the main hazards.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

There are periodic chances for thunderstorms Thursday into the
holiday weekend. Some strong to severe storms may occur at times,
though confidence remains low with the timing of each round of
storms.

LMZ080-261-362-364-366-563-565-567-669-671-673-675-777-779-868-
870-872-874-876-878-020615-
Lake Michigan Michigan City IN to St. Joseph MI 5 NM offshore to
mid-line of lake.-
Lake Michigan from Seul Choix Point to Rock Island Passage 5NM
offshore to Mid Lake-
Lake Michigan South of a line from Seul Choix Point to the
Mackinac Bridge and North of a line from Charlevoix MI to South
Fox Island 5NM offshore-
Lake Michigan from Charlevoix to Point Betsie MI 5NM Offshore to
mid lake-
Lake Michigan from Point Betsie to Manistee MI 5NM offshore to
Mid Lake-
Lake Michigan from Rock Island Passage to Sturgeon Bay WI 5NM
offshore to mid lake-
Lake Michigan from Sturgeon Bay to Two Rivers WI 5NM offshore to
Mid Lake-
Lake Michigan from Two Rivers to Sheboygan WI 5NM offshore to Mid
Lake-
Lake Michigan from Sheboygan to Port Washington WI 5NM offshore
to Mid Lake-
Lake Michigan from Port Washington to North Point Light WI 5NM
offshore to Mid Lake-
Lake Michigan from North Point Light to Wind Point WI 5NM
offshore to Mid Lake-
Lake Michigan from Wind Point WI to Winthrop Harbor IL 5NM
offshore to Mid Lake-
Lake Michigan from Winthrop Harbor to Wilmette Harbor IL 5NM
offshore to Mid Lake-
Lake Michigan from Wilmette Harbor to Michigan City in 5NM
offshore to Mid Lake-
Lake Michigan from Pentwater to Manistee MI 5NM offshore to Mid
Lake-
Lake Michigan from Whitehall to Pentwater MI 5NM offshore to Mid
Lake-
Lake Michigan from Grand Haven to Whitehall MI 5NM offshore to
Mid Lake-
Lake Michigan from Holland to Grand Haven MI 5NM offshore to Mid
Lake-
Lake Michigan from South Haven to Holland MI 5NM offshore to Mid
lake-
Lake Michigan from St Joseph to South Haven MI 5NM offshore to
Mid Lake-
107 AM CDT Wed Jul 1 2026

This Hazardous Weather Outlook is for the open waters of Lake
Michigan.

.DAY ONE...Today and Tonight

Patchy dense fog may occur over northern portions of the lake.

There are mainly small chances for thunderstorms into this
morning over northern portions of the lake, with chances for
storms across this area tonight. Some strong to severe storms are
possible, mainly in the evening. Damaging winds and hail are the
main hazards.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

Areas of dense fog may occur at times into the holiday weekend,
due to the very warm and humid airmass over the colder waters of
Lake Michigan.

There are chances for thunderstorms across the southern two
thirds of the lake Thursday into Friday night, and across the
southern half of the lake over the holiday weekend. Some strong
to severe storms may occur at times, though confidence remains low
with the timing of each round of storms.

Wood
www.weather.gov/mkx

Special Weather Statement
National Weather Service Milwaukee/Sullivan WI
636 AM CDT Wed Jul 1 2026

WIZ046-057-011200-
Columbia WI-Marquette WI-
636 AM CDT Wed Jul 1 2026

...A STRONG THUNDERSTORM WILL IMPACT NORTH CENTRAL COLUMBIA AND
SOUTHWESTERN MARQUETTE COUNTIES THROUGH 700 AM CDT...

At 636 AM CDT, Doppler radar was tracking a strong thunderstorm 8
miles northwest of Portage, moving northeast at 30 mph.

HAZARD...Wind gusts up to 40 mph and half inch hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor hail damage to vegetation is
         possible.

Locations impacted include...
Packwaukee, Endeavor, and Briggsville.

This includes Interstate 39 between mile markers 93 and 104.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4380 8941 4363 8927 4357 8961 4364 8966
      4364 8960 4368 8960
TIME...MOT...LOC 1136Z 240DEG 25KT 4364 8957

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...40 MPH

CMILLER