Alert archive / Wisconsin / Severe Thunderstorm Warnings in 2026

Severe Thunderstorm Warning 8, NWS Green Bay, WI

April 13, 2026Marathon County, Portage County, Wisconsin

NWS Green Bay, WI issued this severe thunderstorm warning at Apr 13, 2026, 4:22 PM CDT for Marathon County, Portage County, Wisconsin. It was in force for 53 min. 2 reports came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued
Apr 13, 2026, 4:22 PM CDT (21:22 UTC)
Expired
Apr 13, 2026, 5:15 PM CDT
In force
53 min
Issued by
NWS Green Bay, WI
Area
Storm-based polygon
Hail
1.0 in
Wind
50.0 mph

Counties Marathon County, WI, Portage County, WI

The radar

The Green Bay radar (KGRB), 108 km from the middle of the area, began a volume at 21:26 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

What was reported inside it

TimeReportWhereRemark
Apr 13, 4:34 PM CDTHAIL 1Ellis, WI&&
Apr 13, 4:34 PM CDTHAIL 1Ellis, WI

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

Did it verify

Verified. The Iowa Environmental Mesonet's Cow matched 2 storm reports to this severe thunderstorm warning; the first came 12 minutes after it went out.

Cow counts a report within 15 km of the polygon while the warning was in force: a tornado for a tornado warning; hail of 1 inch or more, a gust of 58 mph or more or wind damage for a severe thunderstorm warning; a flash flood report for a flash flood warning.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

IssuedProductOfficeLasted
Apr 13, 3:11 PM CDTTornado WatchSPC7 hr

The nearest sounding before it

Minneapolis, MN (KMPX), launched 12:00Z, 9.4 hours before the alert went out and 328 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-pSkew-T log-p diagram, Minneapolis, MN at 12:00Z on 2026-04-13Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 8 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Minneapolis, MN at 12:00Z on 2026-04-13The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 124 square meters per square second.19395878Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
8 J/kg
Mixed-layer CIN
-259 J/kg
Mixed-layer LCL
1506 m above ground
0-6 km bulk shear
45 kt
0-1 km storm-relative helicity
124 m²/s²
0-3 km storm-relative helicity
229 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

992 
WUUS53 KGRB 132122
SVRGRB
WIC073-097-132215-
/O.NEW.KGRB.SV.W.0008.260413T2122Z-260413T2215Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Green Bay WI
422 PM CDT Mon Apr 13 2026

The National Weather Service in Green Bay has issued a

* Severe Thunderstorm Warning for...
  Southeastern Marathon County in central Wisconsin...
  Northeastern Portage County in central Wisconsin...

* Until 515 PM CDT.

* At 422 PM CDT, a severe thunderstorm was located 7 miles northeast
  of Stevens Point, moving northeast at 20 mph.

  HAZARD...Quarter size hail.

  SOURCE...Radar indicated.

  IMPACT...Damage to vehicles is expected.

* This severe thunderstorm will be near...
  Stevens Point around 425 PM CDT.

Other locations impacted by the severe thunderstorm include Ellis,
Jordan, Polonia, Dewey Marsh Wildlife Area, Stockton, Park Ridge,
North Star, Rosholt, Shantytown and Holt.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Seek shelter inside a well-built structure and stay away from
windows. This storm is capable of producing large hail.

Torrential rainfall is also occurring with this storm and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

A Tornado Watch remains in effect until 1000 PM CDT Monday for a
portion of central Wisconsin.

&&

LAT...LON 4469 8961 4487 8958 4485 8923 4468 8923
      4448 8929 4454 8963
TIME...MOT...LOC 2121Z 203DEG 15KT 4460 8947

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...<50 MPH

$$

Kurimski
3 follow-up statements
722 
WWUS53 KGRB 132134
SVSGRB

Severe Weather Statement
National Weather Service Green Bay WI
434 PM CDT Mon Apr 13 2026

WIC073-097-132215-
/O.CON.KGRB.SV.W.0008.000000T0000Z-260413T2215Z/
Marathon WI-Portage WI-
434 PM CDT Mon Apr 13 2026

...SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 515 PM CDT FOR
SOUTHEASTERN MARATHON AND NORTHEASTERN PORTAGE COUNTIES...

At 434 PM CDT, a severe thunderstorm was located 7 miles southwest of
Bevent, or 11 miles northeast of Stevens Point, moving northeast at
30 mph.

HAZARD...Quarter size hail.

SOURCE...Radar indicated.

IMPACT...Damage to vehicles is expected.

This severe thunderstorm will be near...
  Bevent around 450 PM CDT. Weston around 455 PM CDT.

Other locations impacted by the severe thunderstorm include
Shantytown, North Star, Dewey Marsh Wildlife Area, Ellis, Rosholt,
Holt, Galloway, Pike Lake and Elderon.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Seek shelter inside a well-built structure and stay away from
windows. This storm is capable of producing large hail.

Torrential rainfall is also occurring with this storm and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

A Tornado Watch remains in effect until 1000 PM CDT Monday for a
portion of central Wisconsin.

&&

LAT...LON 4469 8961 4487 8958 4485 8923 4468 8923
      4453 8927 4459 8962
TIME...MOT...LOC 2122Z 207DEG 26KT 4460 8951

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...<50 MPH

$$

Kurimski
083 
WWUS53 KGRB 132152
SVSGRB

Severe Weather Statement
National Weather Service Green Bay WI
452 PM CDT Mon Apr 13 2026

WIC073-097-132215-
/O.CON.KGRB.SV.W.0008.000000T0000Z-260413T2215Z/
Marathon WI-Portage WI-
452 PM CDT Mon Apr 13 2026

...SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 515 PM CDT FOR
SOUTHEASTERN MARATHON AND NORTHEASTERN PORTAGE COUNTIES...

At 452 PM CDT, a severe thunderstorm was located over Bevent, or 20
miles northeast of Stevens Point, moving northeast at 30 mph.

HAZARD...Quarter size hail.

SOURCE...Radar indicated.

IMPACT...Damage to vehicles is expected.

This severe thunderstorm will be near...
  Bevent around 455 PM CDT.

Other locations impacted by the severe thunderstorm include Pike
Lake, Holt, Galloway and Elderon.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Seek shelter inside a well-built structure and stay away from
windows. This storm is capable of producing large hail.

Torrential rainfall is also occurring with this storm and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

A Tornado Watch remains in effect until 1000 PM CDT Monday for a
portion of central Wisconsin.

&&

LAT...LON 4469 8950 4486 8941 4485 8923 4468 8923
      4458 8926 4463 8947
TIME...MOT...LOC 2134Z 222DEG 24KT 4466 8944

HAIL THREAT...RADAR INDICATED
MAX HAIL SIZE...1.00 IN
WIND THREAT...RADAR INDICATED
MAX WIND GUST...<50 MPH

$$

Kurimski
234 
WWUS53 KGRB 132205
SVSGRB

Severe Weather Statement
National Weather Service Green Bay WI
505 PM CDT Mon Apr 13 2026

WIC073-097-132215-
/O.EXP.KGRB.SV.W.0008.000000T0000Z-260413T2215Z/
Marathon WI-Portage WI-
505 PM CDT Mon Apr 13 2026

...SEVERE THUNDERSTORM WARNING WILL EXPIRE AT 515 PM CDT FOR
SOUTHEASTERN MARATHON AND NORTHEASTERN PORTAGE COUNTIES...

The storm which prompted the warning has moved out of the area.
Therefore, the warning will be allowed to expire.

A Tornado Watch remains in effect until 1000 PM CDT Monday for a
portion of central Wisconsin.

&&

LAT...LON 4469 8950 4486 8941 4485 8923 4468 8923
      4458 8926 4463 8947
TIME...MOT...LOC 2152Z 222DEG 24KT 4476 8932

$$

Kurimski

What forecasters said that day

The local office's own words before this severe thunderstorm warning went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Green Bay, WI wrote its last area forecast discussion before this severe thunderstorm warning went out at Apr 13, 2:44 PM CDT, 1 hour 38 minutes earlier. Its key messages:

  • Thunderstorms will develop late this afternoon and continue into the overnight hours with hail in excess of 2 inches, damaging winds and a tornado possible with the strongest storms. The highest risk is across central Wisconsin.
  • Rainfall amounts of 1 to 3 inches across parts of central into east-central Wisconsin may lead to additional flood concerns through tonight.
  • An active stretch of weather continues through late week with continued periods of showers and storms. The risk area for severe storms shifts south on Tuesday, but extends north into parts of central and east-central Wisconsin.
  • Minor to moderate river flooding is ongoing or forecast to occur on several area rivers. Expect many rivers to rise this week due to additional rain and runoff from Upper Michigan, with the greatest impacts expected on the Menominee River, where some locations may see major flooding during the mid to late part of the week.
Area forecast discussion, Apr 13, 2:44 PM CDT, 1 hour 38 minutes before
Area Forecast Discussion
National Weather Service Green Bay WI
244 PM CDT Mon Apr 13 2026

.KEY MESSAGES...

- Thunderstorms will develop late this afternoon and continue
  into the overnight hours with hail in excess of 2 inches,
  damaging winds and a tornado possible with the strongest
  storms. The highest risk is across central Wisconsin.

- Rainfall amounts of 1 to 3 inches across parts of central into
  east-central Wisconsin may lead to additional flood concerns
  through tonight.

- An active stretch of weather continues through late week with
  continued periods of showers and storms. The risk area for
  severe storms shifts south on Tuesday, but extends north into
  parts of central and east-central Wisconsin.

- Minor to moderate river flooding is ongoing or forecast to
  occur on several area rivers. Expect many rivers to rise this
  week due to additional rain and runoff from Upper Michigan,
  with the greatest impacts expected on the Menominee River,
  where some locations may see major flooding during the mid to
  late part of the week.

&&

.DISCUSSION...
Issued at 245 PM CDT Mon Apr 13 2026

Tonight: Severe Storms/Heavy Rain

Early afternoon surface analysis indicated a surface low over
central Nebraska with a warm front snaking eastward across
northern Iowa into central Wisconsin. MLCAPE has increased to
around 1000 J/kg across central Wisconsin with some inhibition
noted.

Late this afternoon, expect more focused storm
initiation/intensification generally in the vicinity of the
warm front and nose of the low- level jet. Surface-based
instability is maximized over central Wisconsin (1000-2000 J/kg)
by late this afternoon with effective shear around 40-50 kts.
Combined with steep lapse rates already sampled by the 18Z GRB
RAOB, the environment will be supportive of large to very large
hail. The tornado risk likely will be highest along the warm
front from west-central Wisconsin into perhaps central
Wisconsin as the low-level jet increases early this evening and
overlaps the warm front/instability axis. Damaging wind risk
will depend on the degree of upscale growth/organization of
storms. Overall, the severe weather risk lessens with northward
extent.

Precipitable water values remain near the top of climatology for
mid April. HREF probability matched mean 24-hr rainfall is in
the 1 to 3 inch range across parts of central into east-central
Wisconsin through tonight, on the nose of the low-level jet.
However, rainfall amounts will depend on the organization and
degree of training. This rainfall could exacerbate already
saturated soils.

Areas of fog may also develop overnight behind the storms.

Tuesday: Additional storms

The front slides south on Tuesday with the instability axis also
displaced south. The placement of the boundary will impact the
northward extent of severe weather during the
afternoon/evening. RAP hodographs show lesser low-level shear
although an elongated profile favorable for large hail and
winds. Currently the highest risk of severe storms is across
southern Wisconsin, but could extend into parts of east-central
Wisconsin.

Wednesday-Monday: Active into the weekend

Southwest flow aloft persists into late week keeping the area in
a warm, wet pattern. Another shortwave trough will bring
additional shower (40-80%) chances Wednesday into Thursday. A
more dynamic trough is slated to impact the region late Friday
into the weekend bringing additional widespread rainfall and
storms. The northward extent of greater instability is somewhat
uncertain with this system, impacting severe weather potential,
but this will be something to watch in the coming days. Drier
and cooler weather is expected behind this system for early next
week.

&&

.AVIATION /18Z TAFS THROUGH 18Z TUESDAY/...
Issued at 1251 PM CDT Mon Apr 13 2026

Widespread showers and storms will develop late this afternoon
into the overnight hours with MFVR/IFR conditions. Initial
storms may begin to initiate by 21-22Z today, becoming more
widespread this evening. Areas of fog/low clouds will likely
persist into Tuesday.

&&

.HYDROLOGY...
Issued at 245 PM CDT Mon Apr 13 2026

Flooding is expected to continue on several area rivers during
the week, and will be exacerbated by periodic heavy rainfall.
Runoff from Upper Michigan is still expected to bring moderate
to major flooding along the Menominee River, especially during
the mid to late part of the week. If you live near a river or
stream, keep a close eye on water levels this week and monitor
the latest Flood Warnings from the National Weather Service in
Green Bay.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
WI...Flood Watch through Tuesday morning for WIZ013-018>022-030-031-
     035>040-045-048>050-073-074.
MARINE...None.

&&

DISCUSSION...JM
AVIATION...JM
HYDROLOGY...Kieckbusch/JM
Hazardous weather outlook, Apr 13, 2:51 PM CDT, 1 hour 31 minutes before
Hazardous Weather Outlook
National Weather Service Green Bay WI
251 PM CDT Mon Apr 13 2026

WIZ005-010>013-018>022-030-031-035>040-045-048>050-073-074-142000-
Vilas-Oneida-Forest-Florence-Northern Marinette County-Lincoln-
Langlade-Menominee-Northern Oconto County-Door-Marathon-Shawano-
Wood-Portage-Waupaca-Outagamie-Brown-Kewaunee-Waushara-Winnebago-
Calumet-Manitowoc-Southern Marinette County-
Southern Oconto County-
251 PM CDT Mon Apr 13 2026

This Hazardous Weather Outlook is for north-central and northeast
Wisconsin.

.DAY ONE...Tonight

Elevated water levels or flooding continue along some rivers.

Severe storms, including heavy rainfall, large to very large hail,
damaging winds and tornado or two are possible late this afternoon
into tonight. The highest risk of severe storms is across central
into east- central Wisconsin.

Additional flooding may occur for areas that receive heavy
rainfall tonight.

.DAYS TWO THROUGH SEVEN...Tuesday through Monday

There is a chance of severe thunderstorms south of a line from
Wisconsin Rapids to Sturgeon bay during the late afternoon and
evening on Tuesday. Large hail and strong winds will be the
primary threats.

Additional thunderstorms are possible Wednesday afternoon into
Wednesday night, and again Friday night into Saturday.

Elevated water levels and at least minor flooding will continue
along many rivers through the week. Runoff from the Upper
Peninsula will likely result in moderate to possibly major flooding
on the Menominee River during the mid to late part of the week.

.SPOTTER INFORMATION STATEMENT...

Spotters should report severe weather and flooding to the
National Weather Service in Green Bay.

LMZ521-522-541>543-142000-
The Bay of Green Bay south of a line from Cedar River MI to Rock
Island Passage-Lake Michigan from Washington Island to Sheboygan-
251 PM CDT Mon Apr 13 2026

This Hazardous Weather Outlook is for portions of northwest Lake
Michigan and the waters of Green Bay.

.DAY ONE...Tonight

Thunderstorms, some possibly strong to severe, are expected
tonight.

Areas of fog are possible.

.DAYS TWO THROUGH SEVEN...Tuesday through Monday

Thunderstorms will be possible at times Tuesday through Wednesday
night, and again Friday night into Saturday. Severe storms will
be possible Tuesday evening.

In the hours before

Special weather statement, Apr 13, 4:16 PM CDT, 6 minutes before
Special Weather Statement
National Weather Service Green Bay WI
416 PM CDT Mon Apr 13 2026

WIZ030-036-132145-
Marathon WI-Portage WI-
416 PM CDT Mon Apr 13 2026

...A STRONG THUNDERSTORM WILL IMPACT NORTHEASTERN PORTAGE AND
SOUTHEASTERN MARATHON COUNTIES UNTIL 445 PM CDT...

At 416 PM CDT, Doppler radar was tracking a strong thunderstorm 5
miles northeast of Stevens Point, moving northeast at 20 mph.

HAZARD...Wind gusts up to 40 mph and penny size hail.

SOURCE...Radar indicated.

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

The strong thunderstorm will be near...
  Stevens Point and Whiting around 420 PM CDT.

Other locations impacted by this strong thunderstorm include Jordan,
Ellis, Polonia, Stockton, Park Ridge, Custer, Dewey Marsh Wildlife
Area, North Star, Shantytown and Holt.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Monitor the weather situation closely and be alert for threatening
weather conditions.

This storm may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

&&

LAT...LON 4469 8963 4477 8962 4475 8922 4472 8922
      4449 8932 4449 8965
TIME...MOT...LOC 2116Z 203DEG 15KT 4458 8948

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...40 MPH

Kurimski

The office that day

Everything else NWS Green Bay, WI issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 12, 11:33 PM CDTRiver Flood WarningGRBShawano, Waupaca5 days
Apr 13, 2:04 AM CDTFlood WatchGRBBrown, Calumet, Door, Kewaunee, Langlade, Lincoln and 12 more49 hr
Apr 13, 7:30 AM CDTRiver Flood WarningGRBPortage4 days
Apr 13, 7:31 AM CDTRiver Flood WarningGRBPortage3 days
Apr 13, 10:53 AM CDTRiver Flood WarningGRBLincoln, Marathon11 hr
Apr 13, 3:49 PM CDTSmall Craft AdvisoryGRB7 hr
Apr 13, 4:10 PM CDTRiver Flood WarningGRBFlorence, Forest8 days
Apr 13, 4:16 PM CDTSpecial Weather StatementGRBPortage29 min
Apr 13, 4:43 PM CDTSevere Thunderstorm WarningGRBShawano, Waupaca62 min
Apr 13, 4:44 PM CDTRiver Flood WarningGRBMarinette4 days
Apr 13, 4:46 PM CDTSevere Thunderstorm WarningGRBMarathon59 min
Apr 13, 5:03 PM CDTSevere Thunderstorm WarningGRBPortage, Wood57 min
Apr 13, 5:07 PM CDTSpecial Weather StatementGRBMenominee23 min
Apr 13, 5:22 PM CDTFlash Flood WarningGRBMarathon, Portage, Wood5 hr
Apr 13, 5:23 PM CDTSpecial Weather StatementGRBMenominee37 min
Apr 13, 5:41 PM CDTSevere Thunderstorm WarningGRBMarathon, Wood48 min
Apr 13, 5:42 PM CDTSevere Thunderstorm WarningGRBLanglade, Marathon, Shawano48 min
Apr 13, 5:45 PM CDTMarine Dense Fog AdvisoryGRB67 hr
Apr 13, 5:47 PM CDTAreal Flood AdvisoryGRBLanglade, Menominee, Oconto, Shawano, Waupaca3 hr
Apr 13, 5:55 PM CDTAreal Flood AdvisoryGRBMarathon, Portage3 hr
Apr 13, 5:59 PM CDTSpecial Weather StatementGRBMarinette46 min
Apr 13, 6:19 PM CDTSevere Thunderstorm WarningGRBPortage, Waupaca41 min
Apr 13, 6:37 PM CDTSpecial Weather StatementGRBBrown, Outagamie38 min
Apr 13, 6:39 PM CDTSpecial Weather StatementGRBLincoln36 min
Apr 13, 6:44 PM CDTSevere Thunderstorm WarningGRBLincoln, Marathon35 min
Apr 13, 6:49 PM CDTSevere Thunderstorm WarningGRBOutagamie, Shawano, Waupaca41 min
Apr 13, 6:55 PM CDTSevere Thunderstorm WarningGRBMarathon29 min

Nearby

Severe Thunderstorm Warnings in Wisconsin, 2026Every severe thunderstorm warning in 2026

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.