Special Weather Statement, NWS Green Bay, WI

Area Forecast Discussion
National Weather Service Green Bay WI
325 PM CDT Wed Jul 28 2021

Forecast discussion for routine afternoon forecast issuance

.SHORT TERM...Tonight and Thursday
Issued at 324 PM CDT Wed Jul 28 2021

Some elevated convection will move across north central Wisconsin
during the late afternoon hours, while more organized activity
forms across northern Minnesota in association with a surface low
and cold front. An elevated layer of smoke and significant middle
and high clouds has slowed destabilization across the area today,
but surface dewpoints have risen into the upper 60s to low 70s and
large scale forcing will become much more favorable this evening
as a strong upper trough moves across the area.

We expect an organized convective complex to moves across the region
this evening, with damaging winds and flooding rains the main threat.
Wet bulb zero heights are fairly high, so the threat of large hail
should be mainly associated any supercell thunderstorms that
occur. LCL heights and shear are somewhat favorable for tornadoes
with any discrete storms early this evening and for QLCS activity
later in the evening.

Precipitable water values are near record values, and will make for
an urban and small stream flood threat despite the quick moving storms.
The Green Bay and Fox City areas could have urban flooding with an
inch and a half of ran in an hour. The precipitation will end overnight
with cooler and less humid air arriving Thursday.

.LONG TERM...Thursday Night Through Wednesday
Issued at 324 PM CDT Wed Jul 28 2021

Northwest upper flow will make for cooler and drier weather for
Thursday night through Friday night. An upper trough and surface
cold front should produce sufficient instability for a period of
showers and thunderstorms Saturday. Forecast soundings predict
CAPE values of 1000 to 1500 J/Kg thanks largely to cold
temperatures aloft and surface dewpoints in the low 60s. Gusty
winds and hail look possible.

Dry and cool weather should follow for Sunday through Tuesday with
somewhat warmer temperatures after that as upper ridging edges
closer from the Plains states.
&&

.AVIATION...for 18Z TAF Issuance
Issued at 1230 PM CDT Wed Jul 28 2021

Scattered showers and thunderstorms are expected to move toward
central WI early to mid-afternoon and weaken in the process. There
will also be a scattered MVFR/low-end VFR cu field over most of
the area as well.

The main story remains the likelihood of strong to severe
thunderstorms this evening. Timing still looks like early evening
northern WI and mid to late evening central/east-central WI. While
damaging winds will be the main threat, hail and a tornado are
also possible. Furthermore, torrential downpours would lower
visibility. Look for cigs/vsbys to drop into the MVFR/IFR range
with the storms, then potentially lower into the LIFR range late
tonight as patchy fog develops behind the storms.

The morning fog should be gone by 14Z Thursday morning with VFR
conditions expected for the rest of the day. Northerly winds of 10
to 15 knots are forecast with a few gusts approaching 20 knots,
especially during the afternoon.
&&

.GRB WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

SHORT TERM.....RDM
LONG TERM......RDM
AVIATION.......Kallas

Hazardous Weather Outlook
National Weather Service Green Bay WI
335 PM CDT Wed Jul 28 2021

WIZ005-010>013-018>022-030-031-035>040-045-048>050-073-074-292045-
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-
335 PM CDT Wed Jul 28 2021

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

.DAY ONE...Tonight

Scattered non severe thunderstorms are possible across northcentral
Wisconsin late this afternoon. Some severe thunderstorms are expected
this evening, and a significant severe weather event is possible.
Damaging winds and local flooding rainfall are the main threats,
but large hail and tornadoes are possible.

.DAYS TWO THROUGH SEVEN...Thursday through Wednesday

Thunderstorms are possible Saturday as a cold front moves across
the area. A few storms with hail and gusty winds are possible.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will likely be needed this evening.

LMZ521-522-541>543-292045-
The Bay of Green Bay south of a line from Cedar River MI to Rock
Island Passage-Lake Michigan from Washington Island to Sheboygan-
335 PM CDT Wed Jul 28 2021

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

.DAY ONE...Tonight

Thunderstorms with strong winds, hail, and dangerous lightning
could create hazardous conditions for mariners tonight.

.DAYS TWO THROUGH SEVEN...Thursday through Wednesday

Winds and waves may approach small craft criteria Thursday afternoon
and evening, especially in areas adjacent to northern Door County.

Thunderstorms could create hazardous conditions Saturday.

RDM/RDM

Special Weather Statement
National Weather Service Green Bay WI
616 PM CDT Wed Jul 28 2021

WIZ005-010-011-018-290000-
Vilas WI-Oneida WI-Forest WI-Lincoln WI-
616 PM CDT Wed Jul 28 2021

...SIGNIFICANT WEATHER ADVISORY FOR WEST CENTRAL FOREST...LINCOLN...
SOUTHWESTERN VILAS AND ONEIDA COUNTIES UNTIL 700 PM CDT...

At 615 PM CDT, Doppler radar was tracking a strong thunderstorm near
Willow Reservoir, or 22 miles northwest of Rhinelander, moving
southeast at 50 mph.

Pea size hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Rhinelander, Merrill, Lac Du Flambeau, Tomahawk, Newbold, Harrison,
Woodboro, Headwaters Wilderness, Gilbert and Tripoli.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

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

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

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 4584 9005 4601 8990 4584 8886 4547 8932
      4547 8943 4538 8943 4517 8968 4543 9004
TIME...MOT...LOC 2315Z 306DEG 45KT 4576 8986

EB