Tornado and Flash Flooding in Wisconsin, April 15 to 16, 2026

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
654 PM CDT Wed Apr 15 2026

.KEY MESSAGES...

- Thunderstorms will move across the area this evening posing a
  risk of hail to the size of quarters, wind gusts to 60mph and
  perhaps a tornado or two. This activity has moved into
  southwestern WI and should exit to the east by 11 PM. Areas
  along the WI/IL border and southeastern WI have the best
  chances to see a severe storm.

- Heavy rainfall this evening into the overnight hours will
  maintain a risk for flash flooding into Thursday morning. A
  Flood Watch remains in effect for all of southern Wisconsin.

- Another round of heavy rainfall, flooding, and severe
  thunderstorms is expected Friday afternoon into early
  Saturday morning.

&&

.UPDATE...
Issued 654 PM CDT Wed Apr 15 2026

A messy mesoscale setup this evening as showers and
thunderstorms continue to expand across the region.

Airmass recovery has been slow, but good enough to slip into
southern WI, mainly along/south of I-94 corridor. Best dewpoints
are along/south of the state line and a few supercells have
developed over the past hour or so. Closely monitoring the
behavior of these storms as they approach and cross the state
line, where one of a few nebulous boundaries reside. The
circulation with the supercell just south of Green county has
maintained its character as it has crossed the state line,
which gives at least some indication that there is a boundary in
far southern WI.

For much of the mid/late afternoon, we have observed scattered
to numerous showers and storms north of the boundary, which has
maintained low 60s dewpoints, but have kept temperatures largely
in the low/mid 60s, with the exception of far southeastern WI
where temperatures have poked into the 70s. A slightly better
thermo environment in far southeastern WI is worth noting as we
could see an uptick in intensity as activity moves to the east.

Unlike the past few days, this set up is a bit more uncertain
and subtle mesoscale changes will be the focus to learn if
storms are slightly elevated or becoming more rooted to the
surface, which will open the door to an increased wind
potential, along with the risk for a tornado or two.

Heading into the overnight hours, we will remain moist and as
the shortwave moves into the region additional areas/bands of
showers and embedded storms will linger.

Gagan

&&

.SHORT TERM...
Issued 335 PM CDT Wed Apr 15 2026

Tonight through Thursday night:

More thunderstorms are possible this evening as return flow is
expected to advect appreciable SBCAPE from 1000 to 1500 J/kg
into southwest WI and up to the WI/IL border. Storms tonight may
be a bit weaker than yesterday given skinnier CAPE profiles, but
low level instability, effective shear around 40 knots, and
some curvature in the hodographs will support another round of
gusty winds and hail. An isolated tornado can't be ruled out
along the WI/IL border given the low level turning in the
hodographs and low level instability, provided a low-topped
supercell forms in the environment this afternoon.

Storms will quickly grow upscale after sunset, leading to more
widespread rain. Training thunderstorms may lead to more flash
flooding tonight given the wealth of rain we've had this week. A
Flood Watch is in effect from 4pm this afternoon to 7am Thursday
for the expected rainfall tonight. A widespread 1 to 2 inches
may fall, with locally higher amounts possible where any
thunderstorms track.

Storms largely move offshore tonight around midnight, with more
scattered rain possible between midnight and 7am. Rain should
then largely taper off Thursday morning, with dry conditions
Thursday afternoon. A weak surface ridge will then move overhead
Thursday night.

CMiller

&&

.LONG TERM...
Issued 335 PM CDT Wed Apr 15 2026

Friday through Wednesday:

A strong cold front is expected to move through Friday afternoon
and evening and is expected to lead to another round of severe
weather. At this time the GFS depicts strong warm ahead of the
front which will allow dew points in the 60s to return
northward. Model soundings depict 40 knots of effective shear
amid moderate instability of 2000 J/kg, with low level turning
in the hodographs. This would support all modes of severe
weather again for the area. At this time the SPC has included
southwest and south central Wisconsin in an enhanced risk for
severe weather.

The cold front will then come crashing through Friday night into
Saturday, and temperatures will dip into upper 40s to low 50s
for the weekend. Saturday is expected to be cool and breezy,
with breaks in the clouds late in the day. Sunday will feature
similar conditions but will be a tad bit sunnier as a high
pressure center moves overhead.

Warmth is then expected to return next week Tuesday as a ridge
builds over the central United States. The middle of next week
then looks active again as a low pressure moves off of the lee
of the Rockies.

CMiller

&&

.AVIATION...
Issued 654 PM CDT Wed Apr 15 2026

Primary concern for this evening is another round of showers and
storms. The severe risk is a bit more uncertain, but high enough
to be concerned with localized damaging winds and hail. There is
a small tornado risk. MVFR to brief IFR visibility is expected
with heavy downpours of rain. Lightning risk will be highest
this evening as storms move west to east and exit over the lake
after 04 UTC. Heading into the overnight hours, showers and a
few storms will persist in a scattered fashion, with visibility
and ceilings lowering through the MVFR category. Prior to
daybreak Thursday will be the best window of opportunity for IFR
ceilings and visibility. Conditions will gradually improved
during the day Thursday, with clearing expected in the mid to
late afternoon.

Gagan

&&

.MARINE...
Issued 251 PM CDT Wed Apr 15 2026

A stationary front will remain parked over the middle third of
the lake this afternoon, slowly sinking south to the southern
end of the lake by noon Thursday. A Marine Dense Fog Advisory
continues until Thursday morning while this front lingers.
Winds will remain southerly south of the front and modestly
breezy, while winds north of the front will remain light and
variable to northerly during this time. The front will then
clear the lake Thursday afternoon and northerly winds will
prevail over whole lake. Winds will become light and variable
briefly Thursday night as a weak ridge passes over the lake,
with winds then becoming southerly and breezy Friday ahead of
low pressure of 29.6 inches approaching from the west. Gusty
northwest winds then return following a cold front Friday night.

Additional thunderstorms are forecast over the southern
third of Lake Michigan this evening into tonight. A few storms
could be severe with large hail being the primary concern.
Additional storms are possible Friday into Saturday, with a few
stronger storms possible.

CMiller

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Flood Watch...WIZ046-WIZ047-WIZ051-WIZ052-WIZ056-WIZ057-WIZ058-
     WIZ059-WIZ060-WIZ062-WIZ063-WIZ064-WIZ065-WIZ066-WIZ067-
     WIZ068-WIZ069-WIZ070-WIZ071-WIZ072 until 7 AM Thursday.

LM...Dense Fog Advisory...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-
     LMZ565-LMZ567-LMZ643-LMZ644-LMZ645-LMZ646-LMZ669-LMZ671-
     LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-
     LMZ876-LMZ878 until 7 AM Thursday.

&&

Visit us at weather.gov/milwaukee

Follow us on Facebook, X, and YouTube at:
www.facebook.com/NWSMilwaukee
www.x.com/NWSMilwaukee
www.youtube.com/NWSMilwaukee

Hazardous Weather Outlook
National Weather Service Milwaukee/Sullivan WI
342 PM CDT Wed Apr 15 2026

WIZ046-047-051-052-056>060-062>072-162045-
Marquette-Green Lake-Fond du Lac-Sheboygan-Sauk-Columbia-Dodge-
Washington-Ozaukee-Iowa-Dane-Jefferson-Waukesha-Milwaukee-
Lafayette-Green-Rock-Walworth-Racine-Kenosha-
342 PM CDT Wed Apr 15 2026

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

.DAY ONE...Tonight

A Slight Risk (2 out of 5) for severe weather exists this
afternoon. Primary risks will be hail, gusty winds, though an
isolated tornado can't be ruled out. Southwest Wisconsin and
areas along the WI/IL border have the best chances to see a strong
to severe storm.

Heavy rainfall from more thunderstorms this afternoon and
evening could lead to additional periods of flooding into
Thursday morning. A Flood Watch has been issued for all of
southern Wisconsin.

.DAYS TWO THROUGH SEVEN...Thursday through Wednesday

Additional windows for heavy rainfall, flooding, and severe
thunderstorms Friday into Saturday.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed this evening and again on Friday.

LMZ643>646-162045-
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-
342 PM CDT Wed Apr 15 2026

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

.DAY ONE...Tonight

Dense fog continues for the whole lake through tonight.
Thunderstorms may be possible over the southern end of the lake.

.DAYS TWO THROUGH SEVEN...Thursday through Wednesday

Chances for thunderstorms continue through the end of the week,
with some strong to severe storms possible Friday evening.

Fog may continue into early Thursday afternoon.

LMZ080-261-362-364-366-563-565-567-669-671-673-675-777-779-868-
870-872-874-876-878-162045-
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-
342 PM CDT Wed Apr 15 2026

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

.DAY ONE...Tonight

Dense fog continues for the whole lake through tonight.
Thunderstorms may be possible over the southern end of the lake.

.DAYS TWO THROUGH SEVEN...Thursday through Wednesday

Chances for thunderstorms continue through the end of the week,
with some strong to severe storms possible Friday evening.

Fog may continue into early Thursday afternoon.

www.weather.gov/mkx

Special Weather Statement
National Weather Service Milwaukee/Sullivan WI
644 PM CDT Wed Apr 15 2026

WIZ063-160015-
Dane WI-
644 PM CDT Wed Apr 15 2026

...A STRONG THUNDERSTORM WILL IMPACT NORTHEASTERN DANE COUNTY THROUGH
715 PM CDT...

At 643 PM CDT, Doppler radar was tracking a strong thunderstorm over
northern Madison, moving east at 60 mph.

HAZARD...Wind gusts up to 50 mph and pea size 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...
Madison, Sun Prairie, Middleton, Waunakee, McFarland, Monona,
Windsor, Marshall, Deforest, Cottage Grove, Deerfield, Shorewood
Hills, Maple Bluff, Deansville, East Bristol, Camp Randall Stadium,
Token Creek, Henry Vilas Zoo, and UW-Madison.

This includes the following highways...
 Interstate 39/90/94 between mile markers 127 and 137.
 U.S. Highway 12 between mile markers 249 and 260, and between mile
markers 262 and 269.
 U.S. Highway 151 between mile markers 98 and 112.
 Interstate 39/90 between mile markers 138 and 142.
 Interstate 94 between mile markers 241 and 254.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4323 8967 4328 8901 4305 8901 4303 8956
TIME...MOT...LOC 2343Z 256DEG 50KT 4314 8940

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...50 MPH

DDV

Preliminary Local Storm Report
National Weather Service Milwaukee/Sullivan WI
701 PM CDT Wed Apr 15 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0655 PM     Tstm Wnd Gst     2 NNE Maple Bluff       43.14N 89.35W
04/15/2026  M55 MPH          Dane               WI   ASOS

&&

TP

Special Weather Statement
National Weather Service Milwaukee/Sullivan WI
706 PM CDT Wed Apr 15 2026

WIZ068-069-160030-
Green WI-Rock WI-
706 PM CDT Wed Apr 15 2026

...A STRONG THUNDERSTORM WILL IMPACT SOUTHEASTERN GREEN AND
SOUTHWESTERN ROCK COUNTIES THROUGH 730 PM CDT...

At 705 PM CDT, Doppler radar was tracking a strong thunderstorm
capable of producing a landspout near Brodhead, moving northeast at
30 mph.

HAZARD...Funnel clouds and wind gusts up to 50 mph.

SOURCE...Radar indicated.

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

Locations impacted include...
Brodhead, Orfordville, Juda, and Avon.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4250 8952 4263 8952 4275 8932 4264 8924
      4253 8926
TIME...MOT...LOC 0005Z 246DEG 27KT 4257 8947

LANDSPOUT...POSSIBLE
MAX HAIL SIZE...0.00 IN
MAX WIND GUST...50 MPH

WAGNER

Preliminary Local Storm Report
National Weather Service Milwaukee/Sullivan WI
711 PM CDT Wed Apr 15 2026

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0655 PM     Tstm Wnd Gst     1 WNW Middleton         43.11N 89.53W
04/15/2026  M55 MPH          Dane               WI   AWOS

            Corrects previous tstm wnd gst report from 2
            NNE Maple Bluff.

&&

TP

Special Weather Statement
National Weather Service Milwaukee/Sullivan WI
734 PM CDT Wed Apr 15 2026

WIZ068-069-160100-
Green WI-Rock WI-
734 PM CDT Wed Apr 15 2026

...A STRONG THUNDERSTORM WILL IMPACT SOUTHEASTERN GREEN AND
SOUTHWESTERN ROCK COUNTIES THROUGH 800 PM CDT...

At 733 PM CDT, Doppler radar was tracking a strong thunderstorm
capable of producing a landspout over Brodhead, moving east at 35
mph.

HAZARD...Funnel clouds, wind gusts up to 50 mph, and pea size hail.

SOURCE...Radar indicated.

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

Locations impacted include...
Brodhead, Orfordville, Footville, Newark, and Avon.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4250 8944 4254 8947 4264 8944 4271 8921
      4250 8911
TIME...MOT...LOC 0033Z 248DEG 31KT 4257 8939

LANDSPOUT...POSSIBLE
MAX HAIL SIZE...0.25 IN
MAX WIND GUST...50 MPH

WAGNER

Special Weather Statement
National Weather Service Milwaukee/Sullivan WI
738 PM CDT Wed Apr 15 2026

WIZ069-160115-
Rock WI-
738 PM CDT Wed Apr 15 2026

...A STRONG THUNDERSTORM WILL IMPACT SOUTHEASTERN ROCK COUNTY THROUGH
815 PM CDT...

At 737 PM CDT, Doppler radar was tracking a strong thunderstorm
capable of producing a landspout over South Beloit, moving northeast
at 40 mph.

HAZARD...Funnel Clouds, wind gusts up to 50 mph, and pea size hail.

SOURCE...Radar indicated.

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

Locations impacted include...
Beloit, Clinton, Tiffany, Avalon, Shopiere, and Foxhollow.

This includes the following highways...
 Interstate 39/90 between mile markers 180 and 187.
 Interstate 43 between mile markers 0 and 11.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4250 8912 4253 8914 4261 8898 4267 8878
      4249 8878
TIME...MOT...LOC 0037Z 236DEG 36KT 4247 8906

LANDSPOUT...POSSIBLE
MAX HAIL SIZE...0.25 IN
MAX WIND GUST...50 MPH

WAGNER