Special Weather Statement, NWS Green Bay, WI

Area Forecast Discussion
National Weather Service Green Bay WI
226 PM CDT Sun Aug 23 2020

Forecast discussion for routine afternoon forecast issuance

.SHORT TERM...Tonight and Monday
Issued at 225 PM CDT Sun Aug 23 2020

Main forecast concern continues to be around precipitation trends
into this evening, then again for Monday afternoon. Secondary
concerns focus on max temperatures on Monday as parts of central
and east-central WI could approach 90 degrees with heat indices in
the lower 90s.

The 19Z MSAS surface analysis showed a weak trough that extended
from central Lake Superior southwest through northwest WI into
south-central MN. A cold front was situated over the northern
Plains. The radar mosaic indicated scattered showers and
thunderstorms over north-central WI toward central WI. Otherwise,
a warm and humid afternoon for the rest of the area.

Any showers/thunderstorms over northeast WI should dissipate this
evening as we lose daytime heating, the atmosphere stabilizes and
the surface trough weakens. Skies are expected to briefly clear
for a time, especially over eastern WI before higher clouds start
to move toward central WI during the overnight hours. These
clouds are in advance of the cold front that is forecast to reach
from western Lake Superior to central MN by daybreak. While patchy
fog may develop once again late tonight, the middle/high clouds
set to arrive should prevent the fog from becoming too widespread
or dense. Min temperatures to range from the lower 60s north, to
the middle 60s south.

The cold front is progged to slowly sink south through northern WI
and be the main weather feature for additional precipitation
chances. Ample instability will be present with MUCAPES to range
from 1K-2K J/KG north, to 2500-3500 J/KG south. There will also be
stronger shear with models showing 35-45 knots. Given convergence
along the front, plus some WAA, expect to see an increasing chance
for showers/thunderstorms in the vicinity of the cold front with
the precipitation sagging south toward central/east-central WI
late in the day. Hail and gusty winds would be the primary
threats. Max temperatures to range from the lower 80s north-
central WI, to around 90 degrees over parts of central WI.

.LONG TERM...Monday Night Through Sunday
Issued at 225 PM CDT Sun Aug 23 2020

Zonal flow will continue through most of the work week, with
with a west to east oriented frontal boundary lingering near the
area. The air mass will be very warm, moist and unstable, leading
to the potential for periodic thunderstorm chances (including
nocturnal MCS activity), and the possibility of locally heavy
rainfall and severe weather. Models focus on three main periods of
precipitation, Monday night into early Tuesday (southwest CWA),
late Tuesday night into Wednesday morning (northeast CWA), and
Thursday night into Friday morning. Temperatures through this
period are expected to be much above normal through Thursday, but
daily readings will be dependent on the position of the frontal
boundary, any ongoing precipitation, and debris cloudiness from
nighttime MCS activity. Wednesday looks to to be the warmest day,
with highs reaching the lower 90s in central and east central WI.

There appears to be a severe weather threat on Monday night, and
again Tuesday night into early Wednesday. Both events will be
characterized by mainly elevated instability north of the frontal
boundary, and fairly strong shear. Given the expected elevated
nature of the storms, hail appears to be the main threat, though
wet-bulb zero heights of 10.5-12.5K feet are quite high. PWATs
will be 1.5 to 2 inches, so torrential rainfall and urban flooding
will also be a concern.

Capping should occur after the warm front lifts north on
Wednesday.

Another significant period of precipitation is expected Thursday
night into Friday morning, as a cold frontal system moves through.
Models have ramped up QPF for this event too, so pops may need to
be raised with subsequent forecasts.

A cooler and drier Canadian air mass should return to the area
for the weekend, with temperatures near to a little below normal.
&&

.AVIATION...for 18Z TAF Issuance
Issued at 1246 PM CDT Sun Aug 23 2020

Scattered showers and thunderstorms moving ahead of a weak surface
trough will continue across northern and parts of central WI this
afternoon before dissipating this evening. Cigs/vsbys will drop
into the MVFR range under any of the precipitation, otherwise VFR
conditions to prevail with fair weather cumulus clouds in the 3500
to 4500 ft range.

Skies should clear later this evening, however mid and high clouds
are expected to return to north-central and central WI ahead of an
eastward moving cold front across the Upper MS Valley. Patchy fog
may redevelop, especially where rain occurred. Vsbys could reduced
as low as IFR category toward daybreak with the fog lifting by
around 14Z Monday.

VFR conditions are expected for most of Monday. However, as the
cold front sags into northern WI Monday afternoon, this will bring
the next chance for showers and thunderstorms. Both cigs and vsbys
could drop into the MVFR category under any of the showers/storms.
&&

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

SHORT TERM.....Kallas
LONG TERM......Kieckbusch
AVIATION.......Kallas

Hazardous Weather Outlook
National Weather Service Green Bay WI
233 PM CDT Sun Aug 23 2020

WIZ005-010>013-018>022-030-031-035>040-045-048>050-073-074-241945-
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-
233 PM CDT Sun Aug 23 2020

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

.DAY ONE...Tonight

Scattered thunderstorms are expected into early evening. While
widespread severe weather is not expected, a few strong storms
could produce gusty winds, hail and heavy rain.

.DAYS TWO THROUGH SEVEN...Monday through Sunday

Thunderstorms will be possible at times through the upcoming work
week. There is a slight risk of severe weather over mainly central
and east central Wisconsin Monday night. Large hail, torrential
rainfall and gusty winds will be possible. Another severe threat
may occur over north central and northeast Wisconsin late Tuesday
night into early Wednesday. Large hail and heavy rainfall will be
the main threats.

.SPOTTER INFORMATION STATEMENT...

Although spotter activation should not be needed tonight, spotters
are asked to report any hail, strong winds or rainfall over one
inch.

LMZ521-522-541>543-241945-
The Bay of Green Bay south of a line from Cedar River MI to Rock
Island Passage-Lake Michigan from Washington Island to Sheboygan-
233 PM CDT Sun Aug 23 2020

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 into early evening. Gusty
winds and hail are possible with the strongest storms.

.DAYS TWO THROUGH SEVEN...Monday through Sunday

Thunderstorms will be possible at times through the upcoming work
week. Isolated strong to severe storms are possible Late Monday
night, and late Tuesday night into early Wednesday. Any storms
that develop will pose a hazard to boaters.

Kallas/Kieckbusch

Special Weather Statement
National Weather Service Green Bay WI
1222 PM CDT Sun Aug 23 2020

WIZ005-010-011-018-231815-
Vilas WI-Oneida WI-Forest WI-Lincoln WI-
1222 PM CDT Sun Aug 23 2020

...STRONG THUNDERSTORMS MOVING THROUGH NORTH CENTRAL WISCONSIN...

At 1220 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from 6 miles west of Phelps to near Willow Reservoir
to Ogema. Movement was southeast at 15 mph.

Pea size hail, brief heavy downpours and winds in excess of 30 mph
will be possible with these storms.

Locations impacted include...
Rhinelander, Eagle River, Tomahawk, Newbold, Harrison, Phelps,
Woodboro, Birch Trails Girl Scout Camp, Crystal Lake Scout
Reservation and Rainbow Flowage.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Persons in campgrounds should consider seeking sturdy shelter until
these storms pass.

Boaters and fishermen should head to shore when thunderstorms
approach.

&&

LAT...LON 4614 8909 4602 8882 4602 8869 4585 8868
      4561 8921 4513 8990 4520 9005 4567 9004
      4579 8987 4616 8918
TIME...MOT...LOC 1720Z 300DEG 14KT 4603 8921 4577 8978 4543 9028

Kieckbusch

Special Weather Statement
National Weather Service Green Bay WI
1256 PM CDT Sun Aug 23 2020

WIZ010-018-231900-
Oneida WI-Lincoln WI-
1256 PM CDT Sun Aug 23 2020

...SIGNIFICANT WEATHER ADVISORY FOR LINCOLN AND SOUTHWESTERN ONEIDA
COUNTIES UNTIL 200 PM CDT...

At 1256 PM CDT, Doppler radar was tracking strong thunderstorms along
a line extending from 7 miles southeast of Willow Reservoir to 6
miles southeast of Tripoli to near Rib Lake. Movement was southeast
at 15 mph.

Penny size hail and winds in excess of 40 mph will be possible with
these storms.

Locations impacted include...
Rhinelander, Merrill, Tomahawk, Harrison, Woodboro, Gilbert, Council
Grounds State Park, Birch Trails Girl Scout Camp, New Wood Wildlife
Area and Dutch Corners.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

To report severe weather, contact your nearest law enforcement
agency. They will relay your report to the National Weather Service
office in Green Bay.

&&

LAT...LON 4548 9004 4553 8995 4577 8970 4549 8928
      4547 8930 4547 8943 4536 8942 4520 8960
      4512 8977 4512 9004
TIME...MOT...LOC 1756Z 323DEG 13KT 4566 8971 4548 8990 4534 9018

Kieckbusch

Special Weather Statement
National Weather Service Green Bay WI
248 PM CDT Sun Aug 23 2020

WIZ018-030-232115-
Marathon WI-Lincoln WI-
248 PM CDT Sun Aug 23 2020

...STRONG THUNDERSTORMS MOVING INTO CENTRAL WISCONSIN...

At 243 PM CDT, Doppler radar was tracking several strong
thunderstorms moving into parts of central Wisconsin. These storms
were located 15 miles east of Medford, 10 miles east of Rib Lake and
10 miles southwest of Spirit. Movement was to the south-southeast at
15 mph.

Half inch hail and winds in excess of 30 mph will be possible with
this storm.

Locations impacted include...
Wausau, Weston, Rib Mountain, Mosinee, New Wood Wildlife Area,
Rothschild, Schofield, Knowlton, Stratford and Marathon City.

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.

&&

LAT...LON 4512 9004 4554 9004 4555 8997 4469 8949
      4469 9000 4512 9018
TIME...MOT...LOC 1943Z 340DEG 10KT 4509 9000

Kallas

Special Weather Statement
National Weather Service Green Bay WI
521 PM CDT Sun Aug 23 2020

WIZ021-232245-
Northern Oconto County WI-
521 PM CDT Sun Aug 23 2020

...SPECIAL WEATHER STATEMENT...

At 520 PM CDT, Doppler radar was tracking a strong thunderstorm 7
miles northwest of Mountain, or 26 miles southeast of Crandon, moving
east at 10 mph.

Pea size hail will be possible with this storm.

Locations impacted include...
Mountain, Bear Paw Scout Camp, Lakewood and Boot Lake Campground.

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.

&&

LAT...LON 4530 8837 4510 8841 4520 8864 4521 8864
      4521 8867 4531 8866
TIME...MOT...LOC 2220Z 283DEG 7KT 4526 8860

Cooley