Severe Thunderstorm Warning 26, NWS Green Bay, WI

Area Forecast Discussion
National Weather Service Green Bay WI
339 PM CDT Fri Jul 28 2023

Forecast discussion for routine afternoon forecast issuance

.SHORT TERM...Tonight and Saturday
Issued at 337 PM CDT Fri Jul 28 2023

Complex/messy mesoscale/synoptic set-up making for a complicated
forecast this afternoon into tonight. Main focus will be timing
best chances for storms and if any will be on the strong side.

For this afternoon into tonight...weak surface boundary,
instability gradient and FGEN centered around 850mb, combined
with daytime heating generating MUCAPEs of 1000-2000 J/kg will
continue to produce isolated to scattered showers and storms
extending east-west over parts of central and east-central WI.
Main threats with this activity will be heavy rain and small hail
as they should mainly remain elevated. Then attention turns to
this evening as a more potent shortwave tracks into WI, likely
kicking off additional showers and storms. Instability gradient
still expected to be in place, with the pool of very instability
well to our south in southern WI. Think the strongest of the
storms, along with the main threat for severe weather, will build
south/east into the better instability. We will be on the northern
part of this and it may clip the southern CWA. Models are mixed
on if and how widespread activity north of the main complex will
behave tonight, with the HRRR very aggressive with more widespread
activity, but other models have little to no activity. So
confidence not great on how it will play out as you work to the
north. Plenty of bulk shear to work with (around 50 kts) so any
storms could be well organized and have the chance to produce hail
and some brief gusty winds (especially if a cold pool can get
established with the complex and it clips the southern counties).
Some fog is expected later tonight as temps cool, especially in
central and north central WI where winds are lighter in the
boundary layer. Lows will drop into the 50s to low 60s for most
spots.

For Saturday...some lingering showers will be possible over north
central WI in the early morning, then additional showers will be
possible in the later morning and afternoon as a weak secondary
frontal boundary drops south across northeast WI within a
northwest upper flow, along with a weak shortwave and departing
upper jet. A narrow ribbon of moisture and instability be just
enough to touch off a storm, but will just mention showers for
now. If models continue to trend more aggressive with this
activity, PoPs will need to be expanded. It will be a little
cooler and noticeably less humid with highs in the mid 70s to mid
80s.

.LONG TERM...Saturday Night Through Friday
Issued at 337 PM CDT Fri Jul 28 2023

Summary: Generally quiet weather will prevail Sunday into
Tuesday, outside of warming temperatures. There may be a period of
strong thunderstorms again Wednesday PM as southerly flow returns
and a low pressure system in northern Ontario crosses the Upper
Great Lakes region.

Deep low pressure centered over northern Quebec on Sunday and
amplifying ridging over the northern High Plains keeps the central
United States under mild northwest flow Sunday into Monday. This
is generally expected to be a dry period for north-central and
northeast Wisconsin. Temperatures aloft warm by a degree or two
from Sunday into Monday, but largely support near-normal daytime
high temperatures for the beginning of next week.

The ridge axis aloft shifts eastward into the Missouri Valley
Monday night into Tuesday as lower-level high pressure over the
Upper Midwest drops into the Ohio River Valley. This creates a
return flow into northeast Wisconsin by Tuesday morning. Expect
an increase in daytime high temperatures for Tuesday as a result.
Low pressure over northern Manitoba breaks down the central CONUS
ridge Tuesday night to further increase temperatures Wednesday
ahead of the next chance of possible stronger thunderstorms to
work into northeast Wisconsin later Wednesday. There may be a
chance of severe thunderstorms in this time period as well, but
further analysis will be needed over the next few days pending
similar guidance trends.

Northwest flow may then return behind the cold front later
Thursday as the low then centered in northeast Ontario moves
further eastward.&&

.AVIATION...for 18Z TAF Issuance
Issued at 107 PM CDT Fri Jul 28 2023

An area of low to midlevel frontogenesis is currently working
east southeastward towards Green Bay and the Fox Valley early
this afternoon. Scattered to numerous showers and thunderstorms
will be possible for KGRB-KATW-KOSH mainly between 19-23Z. Large
hail is expected to the primary threat with strong convective
updrafts. A short break will be possible before much broader
deformation forcing arrives across the southern forecast area
mainly between 02-06Z. IFR visibility restrictions in heavy
rainfall will be possible with any activity late this evening.
Cold air advection and saturation in the wake of the upper level
low will likely bring low stratus to the eastern taf sites. Model
data supports enough near surface gradient flow to limit any fg/br
in the east. Fog, potentially LIFR is a greater possibility at
KRHI-KAUW-KCWA.

.KOSH...
TSRA activity to the north and west of the airfield will have the
opportunity to build southward towards KOSH with time. Main
threat for tstorms this afternoon is large hail with visibility
restrictions in heavy rain. Prevailing rain with thunderstorms is
anticipated with 02-06Z as upper level low pressure system passes
to the south of the airfield. Heavy rainfall with some duration
will be possible. Preference is with low stratus instead of fog
late tonight and Saturday morning.
&&

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

SHORT TERM.....Bersch
LONG TERM......NLY
AVIATION.......Behnke

Hazardous Weather Outlook
National Weather Service Green Bay WI
327 PM CDT Fri Jul 28 2023

WIZ005-010>013-018>022-030-031-035>040-045-048>050-073-074-292030-
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-
327 PM CDT Fri Jul 28 2023

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

.DAY ONE...Tonight

There is a chance of thunderstorms, especially across central and
east-central WI. Some of these storms may become strong to
locally severe into this evening, mainly along and south of
Highway 29. Hail, damaging winds, and heavy downpours and
localized flooding are be the primary threats.

.DAYS TWO THROUGH SEVEN...Saturday through Friday

The chance of thunderstorms will return during the Wednesday
through Thursday time frame and may produce some stronger
thunderstorms.

.SPOTTER INFORMATION STATEMENT...

Spotters are requested to report hail, wind gusts over 40 mph, and
rain totals over one inch to the National Weather Service in
Green Bay.

LMZ521-522-541>543-292030-
The Bay of Green Bay south of a line from Cedar River MI to Rock
Island Passage-Lake Michigan from Washington Island to Sheboygan-
327 PM CDT Fri Jul 28 2023

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

.DAY ONE...Tonight

There is a chance of thunderstorms. Some of these storms may
become strong and could pose a hazard to mariners.

.DAYS TWO THROUGH SEVEN...Saturday through Friday

The chance of thunderstorms will return during the Wednesday
through Thursday time frame and may produce some stronger
thunderstorms.

Special Weather Statement
National Weather Service Green Bay WI
339 PM CDT Fri Jul 28 2023

WIZ036>038-282130-
Waupaca WI-Outagamie WI-Portage WI-
339 PM CDT Fri Jul 28 2023

...A strong thunderstorm will impact portions of northeastern
Portage, northern Waupaca and northwestern Outagamie Counties through
430 PM CDT...

At 339 PM CDT, Doppler radar was tracking a strong thunderstorm near
Amherst, or 13 miles east of Stevens Point, moving east at 25 mph.

HAZARD...Winds in excess of 30 mph and half inch hail.

SOURCE...Radar indicated.

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

Locations impacted include...
New London, Clintonville, Manawa, Iola, Bear Creek, Scandinavia,
Peru, Ogdensburg, Nelsonville and Big Falls.

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 4449 8937 4461 8936 4465 8861 4438 8862
TIME...MOT...LOC 2039Z 269DEG 22KT 4453 8928

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...30 MPH

EB

Preliminary Local Storm Report
National Weather Service Green Bay WI
342 PM CDT Fri Jul 28 2023

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

0330 PM     Hail             1 ESE Polonia           44.55N 89.38W
07/28/2023  E0.50 inch       Portage            WI   Public

            Report from mPING: Half-inch (0.50 in.).

&&

Special Weather Statement
National Weather Service Green Bay WI
351 PM CDT Fri Jul 28 2023

WIZ036-037-282130-
Waupaca WI-Portage WI-
351 PM CDT Fri Jul 28 2023

...A strong thunderstorm will impact portions of east central Portage
and central Waupaca Counties through 430 PM CDT...

At 350 PM CDT, Doppler radar was tracking a strong thunderstorm near
Amherst, or 10 miles northwest of Waupaca, moving east at 25 mph.

HAZARD...Winds in excess of 30 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.

Locations impacted include...
Royalton, Manawa, Iola, Amherst Junction, Scandinavia, Peru,
Ogdensburg, Nelsonville, Fitzgerald Corners and Northland.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

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 4447 8931 4460 8927 4456 8874 4430 8881
TIME...MOT...LOC 2050Z 281DEG 21KT 4448 8919

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...30 MPH

EB

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Special Weather Statement
National Weather Service Green Bay WI
602 PM CDT Fri Jul 28 2023

WIZ010-011-013-018>021-030-073-282345-
Southern Marinette County WI-Langlade WI-Northern Oconto County WI-
Marathon WI-Oneida WI-Forest WI-Menominee WI-
Northern Marinette County WI-Lincoln WI-
602 PM CDT Fri Jul 28 2023

...Strong thunderstorms will impact portions of southern Forest,
Lincoln, northern Marathon, northern Marinette, southeastern Oneida,
northwestern Menominee, northern Oconto and Langlade Counties through
645 PM CDT...

At 601 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from near Woodlawn to near Stanley. Movement was
east at 35 mph.

HAZARD...Winds in excess of 30 mph and half inch hail.

SOURCE...Radar indicated.

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

Locations impacted include...
Wausau, Antigo, Crandon, Merrill, Rib Mountain, Tomahawk, Abbotsford,
Harrison, Spencer and Pembine.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

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

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

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.

&&

LAT...LON 4503 9031 4504 9020 4512 9020 4512 9004
      4545 9004 4565 8910 4566 8782 4561 8778
      4556 8783 4555 8782 4527 8800 4503 8922
      4475 9032
TIME...MOT...LOC 2301Z 281DEG 31KT 4547 8893 4503 9088

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...30 MPH

EB