Special Weather Statement, NWS Green Bay, WI

Area Forecast Discussion
National Weather Service Green Bay WI
108 PM CDT Wed Jul 2 2025

Updated aviation portion for 18Z TAF issuance

.KEY MESSAGES...

- There is a chance of thunderstorms this afternoon, especially
  over northern WI. A few storms may become strong to marginally
  severe, especially in far northeast WI between 2 pm and 8 pm.

- Additional chances for rain and storms will be possible Thursday
  through the holiday weekend, with the best chance for widespread
  showers and thunderstorms occurring Saturday and Saturday night.
  There should be a break in the thunderstorm chances for 4th of
  July fireworks displays (Friday evening).

- Temperatures will be above normal through the holiday weekend,
  with very warm and humid conditions (heat indices in the upper
  80s to middle 90s) arriving for the 4th of July.

&&

.DISCUSSION...
Issued at 346 AM CDT Wed Jul 2 2025

Clear to partly cloudy skies were observed across GRB CWA early
this morning. Temperatures ranged from the middle to upper 50s
northwest to around 70 southeast. WV imagery showed a short-wave
trough moving through SW Ontario and northern MN, accompanied by a
cluster of showers and embedded thunderstorms. These showers
should reach north central WI toward midday.

Thunderstorm and Severe Weather Potential this Afternoon: The
short-wave over northern MN will track through northern WI this
afternoon, generating showers and scattered thunderstorms. There
will be some ingredients in place for severe weather, including
CAPE of 1-2K j/kg, deep layer shear of 30 to 35 knots and
inverted-V soundings. However, the strongest forcing will overlap
with the lowest CAPE values over northern WI, so overall
confidence in severe storms is low. SPC HREF 40+ dBZ paintballs
and max wind speeds, and simulated reflectivities off the CAMs,
showed the most organized convection occurring in far NE WI, in
the vicinity of a weak convergence zone/surface trough. Will focus
messaging for severe storms mainly over that region between 2 pm
and 8 pm, even though the SPC Marginal Risk covers the entire CWA.
Coverage of the showers and storms should be less farther south
due to weaker forcing. The main area of showers and storms should
shift east of the region by early evening, but models suggest
continued weak development occurring along a weak frontal boundary
as it sags south during the evening and early overnight.

Thunderstorm Chances through the Holiday Weekend: The weak front
is expected to sag southwest of the region by Thursday, then stall
out through Thursday night. Despite a moist and unstable air mass
over the southwest part of the forecast area, models don't show
much convection developing, likely due to very weak low-level flow
ascending the frontal zone and overall weak forcing. Will only
carry slight chance/chance pops for the southwest CWA during this
period.

The warm front is finally expected to lift northeast through the
forecast area on the 4th of July, though convective coverage will
be limited due to a building upper level ridge over the western
Great Lakes. After the warm front lifts through, generally dry
conditions are expected for evening fireworks displays.

Southwest flow, a stronger short-wave trough and cold frontal
passage will bring a more widespread period of showers and storms
Saturday and Saturday night. Instability (800-1500 j/kg) and deep
layer shear (20-30 knots) will be marginal, and widespread cloud
cover and showers could limit strong to severe thunderstorm
development. PWATs in excess of 2 inches suggest potential for
very heavy rainfall during this period. There is disagreement
on how quickly the cold front will clear the region, but once it
does, there should be a quieter/drier period for at least a day or
two.

Temperatures: Above normal temperatures are expected through
Saturday, followed by near to a little below normal conditions
through the middle of next week. Very warm and muggy conditions
arrive for the 4th of July, with heat indices rising into the
upper 80s to middle 90s during the afternoon. Mild and muggy
conditions will persist through the evening fireworks displays.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 107 PM CDT Wed Jul 2 2025

As of 18Z VFR conditions were noted area-wide with afternoon cu
starting to develop with bases around 4-7kft. Meanwhile, more
substantial cu and weak precip returns were noted in north-central
WI in association with a shortwave coming through. Models have
varied on the handling of afternoon precip, but given the current
development have followed the meso models which show this. A
broken line of showers and some storms will likely develop across
northern WI, and track south through the afternoon and early
evening. Included most likely timing of rain/storms in PROB30
groups, although TEMPO for KRHI where coverage will be a little
better. Dips to mainly MVFR likely within any heavier rain and
thunderstorms.

Activity clears out mid-evening, although still seeing hints at a
few widely scattered showers overnight. Likelihood too low in
include in TAFs, but a few may be around. Meanwhile, fog
development across central and north-central WI late tonight will
likely bring vsbys down to IFR levels for a couple hours.

Winds will generally be from the west around 5-10 kts through
mid- evening, and then subside to light in variable, settling to
the E/SE on Thursday. Gusts of 30-40+ knots could occur within any
thunderstorms.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
None.

&&

DISCUSSION.....Kieckbusch
AVIATION.......KLJ

Hazardous Weather Outlook
National Weather Service Green Bay WI
405 AM CDT Wed Jul 2 2025

WIZ005-010>013-018>022-030-031-035>040-045-048>050-073-074-030915-
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-
405 AM CDT Wed Jul 2 2025

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

.DAY ONE...Today and Tonight

There is a chance of thunderstorms this afternoon and early
evening, with a couple marginally severe storms possible,
especially in far northeast Wisconsin between 2 pm and 8 pm.
Hail and strong winds will be the main threats.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

A few thunderstorms will be possible across the southwest part of
the forecast area Thursday into Thursday night, and across the
forecast area on the 4th of July. There should be a break in the
storms for fireworks displays in the evening.

Very warm and muggy conditions will result in a moderate to
locally high heat risk on the 4th of July. Those with outdoor
plans should take precautions for the heat.

More widespread showers and thunderstorms are expected Saturday
into Saturday night, along with potential for heavy rainfall.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed this afternoon and early evening.

LMZ521-522-541>543-030915-
The Bay of Green Bay south of a line from Cedar River MI to Rock
Island Passage-Lake Michigan from Washington Island to Sheboygan-
405 AM CDT Wed Jul 2 2025

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

.DAY ONE...Today and Tonight

There is a chance of thunderstorms this afternoon and early
evening. Hail and gusty winds may accompany the strongest storms.

.DAYS TWO THROUGH SEVEN...Thursday through Tuesday

There will be a small chance of thunderstorms on the 4th of
July. More widespread showers and storms are expected Saturday
afternoon through Saturday night. Any storms that develop will
pose a threat to mariners.

Kieckbusch

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Special Weather Statement
National Weather Service Green Bay WI
307 PM CDT Wed Jul 2 2025

WIZ019>021-073-074-022045-
Southern Oconto County WI-Southern Marinette County WI-Langlade WI-
Northern Oconto County WI-Menominee WI-
307 PM CDT Wed Jul 2 2025

...A STRONG THUNDERSTORM WILL IMPACT SOUTHERN MARINETTE...
NORTHEASTERN MENOMINEE...NORTHERN OCONTO AND EAST CENTRAL LANGLADE
COUNTIES THROUGH 345 PM CDT...

At 306 PM CDT, Doppler radar was tracking a strong thunderstorm near
Gardner Dam Scout Camp, or 25 miles east of Antigo, moving east at 40
mph.

HAZARD...Wind gusts up to 40 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.

This strong thunderstorm will be near...
  Mountain around 315 PM CDT.

Other locations impacted by this storm include Boot Lake Campground,
Hickory Corners, Breed, Fredenberg Lake, White Potato Lake, Boulder
Lake Campground, Suring, Hayes, Crooked Lake, and Langlade.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4512 8880 4528 8870 4522 8807 4489 8822
TIME...MOT...LOC 2006Z 289DEG 33KT 4518 8863

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH

JG

Special Weather Statement
National Weather Service Green Bay WI
316 PM CDT Wed Jul 2 2025

WIZ018>020-030-031-022115-
Shawano WI-Langlade WI-Marathon WI-Menominee WI-Lincoln WI-
316 PM CDT Wed Jul 2 2025

...STRONG THUNDERSTORMS WILL IMPACT SOUTHWESTERN LINCOLN...
NORTHEASTERN MARATHON...MENOMINEE...SOUTHERN LANGLADE AND WESTERN
SHAWANO COUNTIES THROUGH 415 PM CDT...

At 314 PM CDT, Doppler radar was tracking a broken line of strong
thunderstorms extending from near White Lake to 12 miles southwest
of Antigo to 9 miles southwest of Council Grounds State Park.
Movement was southeast at 20 mph. Some of these storms may produce
up to half inch hail.

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.

Strong thunderstorms will be near...
  Wausau and Neopit around 320 PM CDT.
  Rib Mountain around 330 PM CDT.
  Weston around 335 PM CDT.
  Wittenberg, Legend Lake, and Keshena around 355 PM CDT.

Other locations impacted by these storms include Aniwa, College Of
Menominee Nation, Lake Noseum, Mattoon, Pike Lake, Little Chicago,
Hamburg, Upper Bass Lake, Birnamwood, and Eland.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

&&

LAT...LON 4517 9004 4511 8941 4517 8887 4491 8849
      4486 8849 4477 8900 4482 8992
TIME...MOT...LOC 2014Z 308DEG 19KT 4511 8881 4502 8934 4507 8985

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

JG