Severe Thunderstorm Warning 29, NWS Green Bay, WI

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

Forecast discussion for routine afternoon forecast 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 12Z TAF Issuance
Issued at 628 AM CDT Fri Apr 17 2026

Fog and very low stratus continues near Lake Michigan due to moist
SSE flow off the cold waters. This will likely improve as low-
level winds become southwest this evening, then northwest behind a
cold front overnight.

Thunderstorms storms were develop ahead of a cold front, and are
likely to become severe as they move through the forecast area
between 20z/Fri-01z/Sat. Flight conditions will quickly lower to
MVFR/IFR during the storms, with MVFR and local IFR ceilings
lingering into the late evening and overnight. A second band of
showers will accompany the passage of the cold front tonight.
Expect flight conditions to improve to VFR late tonight into early
Saturday.

South southeast surface winds will gust to 25 to 35 kts this
afternoon, then become NW 15 to 25 kts after the cold front moves
through this evening and overnight. Ahead of the front, periods
of LLWS will continue.

&&

.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.......GK
HYDROLOGY......Kieckbusch

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