Alert archive / Wisconsin / Flash Flood Warnings in 2026

Flash Flood Warning 8, NWS Green Bay, WI

April 17, 20264 counties in Wisconsin

NWS Green Bay, WI issued this flash flood warning at Apr 17, 2026, 6:52 PM CDT for 4 counties in Wisconsin. It was in force for 2 hr. 1 report 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 17, 2026, 6:52 PM CDT (23:52 UTC)
Expired: Apr 17, 2026, 9:15 PM CDT
In force: 2 hr
Issued by: NWS Green Bay, WI
Area: Storm-based polygon
Flood severity: None

Counties Langlade County, WI, Marathon County, WI, Menominee County, WI, Shawano County, WI

The radar

The Green Bay radar (KGRB), 116 km from the middle of the area, began a volume at 23:55 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

Time	Report	Where	Remark
Apr 17, 7:05 PM CDT	FLOOD	2 N Wausau, WI	Street flooding. Also, law enforcement reports minor poor drainage flooding in the area.

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

Did it verify

Not verified. The Iowa Environmental Mesonet's Cow found no qualifying storm report inside this flash flood warning while it was in force. That is not proof nothing happened: reports are thin where few people live.

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 nearest sounding before it

Minneapolis, MN (KMPX), launched 12:00Z, 11.9 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 1 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 2301 m above ground
0-6 km bulk shear: 39 kt
0-1 km storm-relative helicity: 188 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.

996 
WGUS53 KGRB 172352
FFWGRB
WIC067-073-078-115-180215-
/O.NEW.KGRB.FF.W.0008.260417T2352Z-260418T0215Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/

BULLETIN - EAS ACTIVATION REQUESTED
Flash Flood Warning
National Weather Service Green Bay WI
652 PM CDT Fri Apr 17 2026

The National Weather Service in Green Bay has issued a

* Flash Flood Warning for...
  Central Marathon County in central Wisconsin...
  Southeastern Langlade County in north central Wisconsin...
  Northwestern Menominee County in northeastern Wisconsin...
  Western Shawano County in northeastern Wisconsin...

* Until 915 PM CDT.

* At 652 PM CDT, Trained weather spotters reported thunderstorms
  producing heavy rain across the warned area. Between 1 and 2 inches
  of rain have fallen. Flash flooding is ongoing or expected to begin
  shortly.

  HAZARD...Flash flooding caused by thunderstorms.

  SOURCE...Trained spotters reported.

  IMPACT...Flash flooding of small creeks and streams, urban areas,
           highways, streets and underpasses as well as other poor
           drainage and low-lying areas.

* Some locations that will experience flash flooding include...
  Wausau, Antigo, Weston, Rib Mountain, Mosinee, Rothschild,
  Schofield, Ringle, Marathon City, Polar, Evergreen, Aniwa, Sunset,
  Nutterville, Camp Phillips Scout Camp, Hogarty, Rib Mountain State
  Park and Peplin.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Turn around, don't drown when encountering flooded roads. Most flood
deaths occur in vehicles.

Be especially cautious at night when it is harder to recognize the
dangers of flooding.

Be aware of your surroundings and do not drive on flooded roads.

&&

LAT...LON 4468 8985 4478 9002 4496 8982 4504 8945
      4507 8937 4510 8927 4522 8902 4521 8880
      4508 8892 4497 8913 4487 8944 4468 8976

FLASH FLOOD...OBSERVED

$$

JLA

1 follow-up statement

650 
WGUS73 KGRB 180213
FFSGRB

Flash Flood Statement
National Weather Service Green Bay WI
913 PM CDT Fri Apr 17 2026

WIC067-073-078-115-180223-
/O.EXP.KGRB.FF.W.0008.000000T0000Z-260418T0215Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Langlade WI-Marathon WI-Menominee WI-Shawano WI-
913 PM CDT Fri Apr 17 2026

...FLASH FLOOD WARNING WILL EXPIRE AT 915 PM CDT THIS EVENING FOR
CENTRAL MARATHON, SOUTHEASTERN LANGLADE, NORTHWESTERN MENOMINEE AND
WESTERN SHAWANO COUNTIES...

The heavy rain has ended. Flood waters have receded or will slowly
recede. Flash flooding is no longer expected to pose a threat. Please
continue to heed remaining road closures.

A Flood Watch remains in effect until 700 AM CDT Saturday for
portions of central, east central, north central, and northeast
Wisconsin.

&&

LAT...LON 4468 8985 4478 9002 4496 8982 4504 8945
      4507 8937 4510 8927 4522 8902 4521 8880
      4508 8892 4497 8913 4487 8944 4468 8976

$$

Bersch

What forecasters said that day

The local office's own words before this flash flood 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 flash flood warning went out at Apr 17, 6:43 PM CDT, 9 minutes earlier. Its key messages:

-Severe storms with a risk of tornadoes (possibly strong), large hail and damaging winds are increasingly likely from 3 pm to 8 pm today, with the highest risk across central Wisconsin. -Thunderstorms this afternoon and evening will produce locally heavy rainfall. If this occurs over the flood sensitive areas of central and east central WI additional significant flooding may occur. -Minor to major flooding will continue into next week with the greatest impacts expected on the Menominee and Wolf Rivers where major or record breaking flooding has been observed. -No significant precipitation is expected from Saturday through Thursday, but widespread showers and storms may return next Thursday night into Friday.

Area forecast discussion, Apr 17, 6:43 PM CDT, 9 minutes before

Area Forecast Discussion
National Weather Service Green Bay WI
643 PM CDT Fri Apr 17 2026

Updated aviation portion for 00Z TAF issuance

.KEY MESSAGES...

-Severe storms with a risk of tornadoes (possibly strong), large
 hail and damaging winds are increasingly likely from 3 pm to 8 pm
 today, with the highest risk across central Wisconsin.

-Thunderstorms this afternoon and evening will produce locally
 heavy rainfall. If this occurs over the flood sensitive areas of
 central and east central WI additional significant flooding may
 occur.

-Minor to major flooding will continue into next week with the
 greatest impacts expected on the Menominee and Wolf Rivers where
 major or record breaking flooding has been observed.

-No significant precipitation is expected from Saturday through
 Thursday, but widespread showers and storms may return next Thursday
 night into Friday.

&&

.DISCUSSION...
Issued at 125 PM CDT Fri Apr 17 2026

Severe Thunderstorm and Flood Potential This Afternoon/Evening...
Confidence is increasing in a significant, but fairly brief
severe weather event. A narrow axis of SBCAPE (1500-2500 j/kg)
was already developing ahead of a strong cold front over SE MN, NE
IA and SW WI. This was coincident with 0-1km SRH of 200-250.
Radar showed pre-frontal convection occurring in far SW WI and NE
IA, with additional storms developing along the cold front in
eastern MN. CAMs show intense convection, including supercells and
line segments moving through the forecast area between 3 pm and 8
pm. Given the degree of shear, an all-hazard event, including
tornadoes, is expected, with the tornado threat lessening for any
storms nearing the lakeshore, where less instability will be
present. A Tornado Watch has been issued along and south of Hwy 29
(away from Lake Michigan) through 8 pm. A lingering Severe
Thunderstorm Watch is also still in effect for far NC WI until 5
pm. This will be a fairly short-lived event, as instability drops
off rapidly after sunset. An additional band of light to moderate
showers will accompany the cold front later this evening and
overnight. Expect most locations to see between 0.50 and 1 inch of
precipitation with event, which will exacerbate ongoing flooding.
A Flood Watch remains in effect for all but the far northwest
part of the CWA.

The cold frontal passage will bring a period of cooler weather
through the weekend into early next week. The best chance of
precipitation during this period will be 20-40 percent chance of
snow/rain showers over C/EC WI on Sunday, in association with a
short-wave trough and cold frontal passage.

Mainly dry and warmer weather is expected for the middle of next
week, with high temperatures reaching into the 60s and 70s. An
approaching cold front brings another potentially significant
round of showers and storms Thursday night into Friday.

&&

.AVIATION...for 00Z TAF Issuance
Issued at 636 PM CDT Fri Apr 17 2026

Strong thunderstorms were moving across portions of central
and northeast WI, producing very low visibilities in heavy
rain and hail. Strong winds over 40 knots were possible.
The showers and thunderstorms should end from west to east
later this evening into the overnight hours as a strong
cold front moves across the region. Low level wind shear
from the south/southeast around 50 knots will continue
until the front passes. Gusty west to northwest winds
are expected behind it along with a brief period of MVFR
CIGS across the entire area, possibly IFR CIGS across the
north. Conditions should improve into the VFR category
on Saturday with gusty winds continuing into Saturday
evening before winds begin to subside.

&&

.HYDROLOGY...
Issued at 125 PM CDT Fri Apr 17 2026

A Flood Watch is in effect through tonight, due to an expected
half inch to an inch of rain from thunderstorms this afternoon
and evening. Locally higher amounts are possible.

Flooding continues along multiple rivers due to the combination
of snow melt and recent heavy rainfall, including major flooding
along the Wolf and Menominee Rivers. If you live near a river or
stream, continue to monitor the latest hydro forecasts and Flood
Warnings from the National Weather Service in Green Bay.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Flood Watch through Saturday morning for WIZ011>013-019>022-030-
031-035>040-045-048>050-073-074.
&&

DISCUSSION.....Kieckbusch
AVIATION.......Eckberg
HYDROLOGY......Kieckbusch

Hazardous weather outlook, Apr 17, 1:54 PM CDT, 4 hours 58 minutes before

Hazardous Weather Outlook
National Weather Service Green Bay WI
154 PM CDT Fri Apr 17 2026

WIZ005-010>013-018>022-030-031-035>040-045-048>050-073-074-181900-
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-
154 PM CDT Fri Apr 17 2026

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

.DAY ONE...This Afternoon and Tonight

Thunderstorms, some severe with locally heavy rain, will impact
the area between 3 pm and 8 pm. Hazards include large hail, a few
tornadoes, possibly strong, and damaging winds. The highest
threat is across central Wisconsin.

Flooding may occur with the storms, especially in urban areas,
and locations already impacted by heavy rain earlier in the week.

River flooding is expected to continue due to recent heavy
rainfall, with major flooding on parts of the Wolf and Menominee
Rivers.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday

Flooding will continue on some area rivers and streams into next
week.

.SPOTTER INFORMATION STATEMENT...

Spotters are requested to report any severe weather or flooding
to the National Weather Service in Green Bay.

LMZ521-522-541>543-181900-
The Bay of Green Bay south of a line from Cedar River MI to Rock
Island Passage-Lake Michigan from Washington Island to Sheboygan-
154 PM CDT Fri Apr 17 2026

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

.DAY ONE...This Afternoon and Tonight

Areas of dense fog are expected through late tonight. A Dense Fog
Advisory is in effect for the Lake Michigan nearshore waters and
the bay of Green Bay.

Thunderstorms will occur later this afternoon and evening. Any
thunderstorms could be hazardous to boaters.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday

The probability for widespread hazardous weather is low.

Kieckbusch

In the hours before

Local storm report, Apr 17, 5:40 PM CDT, 1 hour 12 minutes before

Preliminary Local Storm Report
National Weather Service Green Bay WI
540 PM CDT Fri Apr 17 2026

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

0538 PM     Funnel Cloud     1 NNW Phlox             45.05N 89.01W
04/17/2026                   Langlade           WI   911 Call Center

            call center called to report a funnel cloud
            going north east of Phlox.

&&

JF

Local storm report, Apr 17, 5:42 PM CDT, 1 hour 10 minutes before

Preliminary Local Storm Report
National Weather Service Green Bay WI
542 PM CDT Fri Apr 17 2026

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

0540 PM     Funnel Cloud     4 WNW Elton             45.17N 88.92W
04/17/2026                   Langlade           WI   911 Call Center

            Langlade dispatch called saying funnel cloud
            seen southwest of Elton.

&&

JF

Local storm report, Apr 17, 6:20 PM CDT, 32 minutes before

Preliminary Local Storm Report
National Weather Service Green Bay WI
620 PM CDT Fri Apr 17 2026

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

0619 PM     Funnel Cloud     2 SSW White Lake        45.13N 88.78W
04/17/2026                   Langlade           WI   911 Call Center

            Call from Shawano county dispatch reporting
            funnel cloud by white lake.

&&

JF

Local storm report, Apr 17, 6:25 PM CDT, 27 minutes before

Preliminary Local Storm Report
National Weather Service Green Bay WI
625 PM CDT Fri Apr 17 2026

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

0625 PM     Flash Flood      1 NW Marshfield         44.67N 90.17W
04/17/2026                   Wood               WI   911 Call Center

            getting reports of cars stuck in water on
            several streets with in Marshfield.

&&

JF

Special weather statement, Apr 17, 6:26 PM CDT, 26 minutes before

Special Weather Statement
National Weather Service Green Bay WI
626 PM CDT Fri Apr 17 2026

WIZ030-031-035-036-180030-
Shawano WI-Wood WI-Marathon WI-Portage WI-
626 PM CDT Fri Apr 17 2026

...STRONG THUNDERSTORMS WILL IMPACT WOOD...PORTAGE...SOUTHEASTERN
MARATHON AND WESTERN SHAWANO COUNTIES THROUGH 730 PM CDT...

At 626 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from near Mosinee to 12 miles north of Wisconsin
Rapids to Babcock. Movement was northeast at 45 mph.

HAZARD...Wind gusts up to 50 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...
Wausau, Stevens Point, Wisconsin Rapids, Weston, Rib Mountain,
Mosinee, Whiting, Bevent, Wittenberg, and Pittsville.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

These storms 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.

A Tornado Watch remains in effect until 800 PM CDT for central, north
central and northeastern Wisconsin.

&&

LAT...LON 4459 9011 4488 8983 4503 8923 4503 8910
      4481 8900 4468 8914 4468 8923 4460 8922
      4434 8949 4425 9032 4430 9032
TIME...MOT...LOC 2326Z 241DEG 41KT 4483 8968 4457 8982 4431 9014

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...50 MPH

Kieckbusch

Special weather statement, Apr 17, 6:43 PM CDT, 9 minutes before

Special Weather Statement
National Weather Service Green Bay WI
643 PM CDT Fri Apr 17 2026

WIZ010-018-180015-
Oneida WI-Lincoln WI-
643 PM CDT Fri Apr 17 2026

...A STRONG THUNDERSTORM WILL IMPACT NORTHWESTERN LINCOLN AND WESTERN
ONEIDA COUNTIES THROUGH 715 PM CDT...

At 643 PM CDT, Doppler radar was tracking a strong thunderstorm over
Tripoli, or 26 miles west of Rhinelander, moving northeast at 50 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 hail damage to vegetation is
         possible.

This strong thunderstorm will be near...
  Willow Reservoir around 655 PM CDT.

Other locations impacted by this storm include Mc Naughton, Lower
Tomahawk River Natural Area, Harshaw, Hazelhurst, Woodruff, Clifford,
Tomahawk River Pines Natural Area, Clear Lake Campground, Indian
Mounds Campground, and Mccord.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

A Tornado Watch remains in effect until 800 PM CDT for north central
Wisconsin.

A Severe Thunderstorm Watch remains in effect until 800 PM CDT for
north central Wisconsin.

&&

LAT...LON 4562 9004 4590 8972 4590 8969 4576 8947
      4542 8994 4549 9005
TIME...MOT...LOC 2343Z 222DEG 54KT 4555 8996

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

MPC

The office that day

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

Issued	Product	Office	Counties	Lasted
Apr 16, 8:36 PM CDT	Dense Fog Advisory	GRB	Brown, Calumet, Door, Forest, Kewaunee, Langlade and 9 more	12 hr
Apr 16, 8:37 PM CDT	Marine Dense Fog Advisory	GRB		31 hr
Apr 17, 2:56 AM CDT	Small Craft Advisory	GRB		31 hr
Apr 17, 2:53 PM CDT	Severe Thunderstorm Warning	GRB	Marathon, Wood	82 min
Apr 17, 3:00 PM CDT	Tornado Warning	GRB	Wood	60 min
Apr 17, 3:27 PM CDT	Severe Thunderstorm Warning	GRB	Wood	48 min
Apr 17, 3:40 PM CDT	Special Weather Statement	GRB	Lincoln	65 min
Apr 17, 3:52 PM CDT	Severe Thunderstorm Warning	GRB	Marathon, Portage, Wood	53 min
Apr 17, 4:10 PM CDT	Flash Flood Warning	GRB	Marathon, Wood	5 hr
Apr 17, 4:11 PM CDT	Special Weather Statement	GRB	Winnebago	34 min
Apr 17, 4:19 PM CDT	Severe Thunderstorm Warning	GRB	Oneida	24 min
Apr 17, 4:21 PM CDT	Tornado Warning	GRB	Marathon	39 min
Apr 17, 4:36 PM CDT	Severe Thunderstorm Warning	GRB	Lincoln	39 min
Apr 17, 4:44 PM CDT	Tornado Warning Tornado observed	GRB	Marathon	32 min
Apr 17, 4:48 PM CDT	Tornado Warning	GRB	Lincoln	21 min
Apr 17, 4:50 PM CDT	Severe Thunderstorm Warning	GRB	Langlade, Lincoln	30 min
Apr 17, 4:52 PM CDT	Tornado Warning	GRB	Langlade, Lincoln	30 min
Apr 17, 5:00 PM CDT	Severe Thunderstorm Warning	GRB	Lincoln, Oneida	45 min
Apr 17, 5:06 PM CDT	Tornado Warning Tornado observed	GRB	Langlade, Marathon, Shawano	39 min
Apr 17, 5:14 PM CDT	Tornado Warning	GRB	Wood	61 min
Apr 17, 5:19 PM CDT	Severe Thunderstorm Warning	GRB	Forest, Langlade, Oneida	18 min
Apr 17, 5:24 PM CDT	Special Weather Statement	GRB	Vilas	36 min
Apr 17, 5:27 PM CDT	Severe Thunderstorm Warning	GRB	Langlade, Marathon, Menominee, Portage, Shawano, Waupaca	37 min
Apr 17, 5:28 PM CDT	Tornado Warning	GRB	Vilas	17 min
Apr 17, 5:30 PM CDT	Tornado Warning	GRB	Langlade, Menominee	45 min
Apr 17, 5:48 PM CDT	Tornado Warning	GRB	Shawano	9 min
Apr 17, 5:58 PM CDT	Severe Thunderstorm Warning	GRB	Vilas	32 min
Apr 17, 6:06 PM CDT	Tornado Warning	GRB	Langlade, Oconto	28 min
Apr 17, 6:26 PM CDT	Special Weather Statement	GRB	Marathon, Portage, Wood	64 min
Apr 17, 6:43 PM CDT	Special Weather Statement	GRB	Oneida	32 min
Apr 17, 6:58 PM CDT	Severe Thunderstorm Warning	GRB	Oneida, Vilas	32 min

Nearby

Flash Flood Warnings in Wisconsin, 2026 Every flash flood 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.