Special Marine Warning 9, NWS Milwaukee, WI

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
Issued by National Weather Service Chicago IL
249 PM CDT Tue Jul 6 2021

.MESOSCALE DISCUSSION...
(Issued 242 PM CDT Tue Jul 6 2021)

Storms have begun to develop along a frontal boundary draped
across or just to the north of our northern tier of counties from
Marquette to Sheboygan in advance of shortwave activity across the
upper Midwest. As forcing increases later this afternoon, an
uncapped atmospehere to the southwest of an onshore moving cold
front will remain in place. Steep low level lapse rates and modest
DCAPE will support a damaging wind threat along and to the south
of the front. 49 kt winds were already observed in Manitowoc.

There is a non zero tornado threat with 100-125 J/KG of 0-3 km
CAPE in place and some enhanced vorticity on the front, especially
in any areas that are able to back winds ahead of the boundary.
The onshore moving front should ease the threat closer to the
shore with time this afternoon.

A severe thunderstorm watch is in effect through mid evening from
Sauk to Dodge county and from Marquette to Sheboygan county.

KMD

&&

.SHORT TERM...
(Issued 425 AM CDT Tue Jul 6 2021)

Today through Wednesday:

A rather complex forecast for the next 36 hours with another day
of very warm conditions, widely scattered afternoon convection
posing a risk for downburst winds and a pneumonia front that will
result in a sharp drop in temperatures along the lake shore from
the mid afternoon into the early evening hours.

We are experiencing a rather warm start to the day as passing
cirrus and a southwest breeze are helping to keep the boundary
layer mixed. Warmest temperatures are along the lake front
counties, with mid to upper 70s quite common. Further west,
temperatures drop off into the lower 70s.

Temperatures will warm quickly this morning, with highs not too
far off from what was observed yesterday. All eyes will be focused
on a pneumonia front that is expected to surge south during the
day today, with current timing in Sheboygan county around 21z.
Confidence in high temps is lowest as it is plausible that front
arrival is a little quicker than anticipate. With dewpoints right
around the 70 degree mark, it will be uncomfortable again with
heat index values well into the 90s.

Thunderstorm chances will increase this afternoon, mainly north
of the I-94 corridor, as we start to feel this influence of lift
from a shortwave and mid level moisture increases. Instability and
buoyancy will be plentiful, but shear will once again be a
limitation. That said, there are indications of a modest increase
in deep shear to between 25 and 30kt by late this afternoon. This
would support multicell clusters and perhaps even a few transient
supercell structures. Soundings suggest an inverted V signature
that supports localized downburst winds with anything that can
develop. Marginally severe hail will also be possible with the
more intense updrafts.

Will need to watch storm interactions with the incoming pneumonia
front. Peak heating will support strong low level lapse rates and
0-3km CAPE exceeding 100 J/kg. The front will likely undercut most
updrafts, but developing storms along the boundary could pose a
risk for a few funnel clouds. The nonsupercell tornado parameter
will be one to keep an eye on this afternoon.

The pneumonia front will eventually stall this evening, with the
synoptic boundary to our north also stalling near or just north of
the WI/IL state line. Weak low pressure riding along this boundary
will maintain the risk for showers/storms north of the front
tonight and into Wednesday. Boundary location will be a big player
in temperatures for tomorrow. Have made a play for some recovery
for areas adjacent to the WI/IL state line (75 to 80 degrees), but
those north of the boundary will struggle to reach the 70 degree
mark, and most locations toward central WI staying in the 60s all
day.

Gagan

&&

.LONG TERM...
(Issued 425 AM CDT Tue Jul 6 2021)

Wednesday night through Monday:

Showers and maybe a few thunderstorms will linger into Wednesday
night, before dissipating as drier air arrives overnight into
Thursday morning. Temperatures Wednesday night look to fall into
the 50s in most locations.

Thursday continues to look like a relatively pleasant day, though
there are some questions as to how much sun we will actually see,
with cyclonic flow aloft favoring a stratus/stratocu deck for much
of the day. Temperatures will be on the cool side, with highs
likely struggling to reach 70 in all but perhaps the far south and
southwest. Winds will be breezy from the north and northeast.

It is starting to look more likely than not that Friday will start
out dry, with precipitation potential increasing later in the day
and especially into Friday night, as ascent increases ahead of a
shortwave dropping through the Dakotas. The track of this wave and
associated precipitation remains in question, with some models
trending further south over the last 24 hours. There will
certainly be showers and thunderstorms in place across the Midwest
and lower Great Lakes during this time, but it's not entirely
clear where exactly the best rain chances will set up. This
unsettled, and uncertain pattern will persist through the weekend,
as the wave slowly moves through the Great Lakes.

Boxell

&&

.AVIATION...
(Issued 840 AM CDT Tue Jul 6 2021)

VFR conditions to continue for bulk of today. Still expect
pneumonia front to affect eastern areas this afternoon with weaker
southwest to southeast winds abruptly switching to the northeast.
This may trigger a few t-storms across the eastern areas with a
rapid wind switch to the northeast and few stronger gusts.
Northeast winds and increasing low level moisture may bring MVFR
or lower clouds to the area later tonight into Wednesday.

Kavinsky

&&

.MARINE...
(Issued 840 AM CDT Tue Jul 6 2021)

Winds beginning to turn more northwest across about the northern
third of Lake Michigan as pneumonia front begins to strengthen due
to upstream pressure rises across Lake Superior and UP. As high
pressure continues to build to the north, the pneumonia front
should accelerate southward later this morning and afternoon, with
a few gusts to 25 knots. The latest GLERL FVCOM estimate of Lake
MI surface water temps show the last several days of breezy
offshore winds have created upwelling of cooler water along the
western shore of the lake. Hence this cooler water may cause the
pneumonia front to accelerate south and west this afternoon. A
Small Craft Advisory for the nearshore waters will remain in
effect for building waves and a brief period of gusty northeast
winds up to 25 knots. Mariners should be alert for the rapid wind
shift to the N-NE this afternoon and evening.

Kavinsky

&&

.BEACHES...(Issued 425 AM CDT Tue Jul 6 2021)

A fast moving front will move south across Lake Michigan and into
southern Wisconsin from the mid afternoon hours into this
evening. This will result in a sharp change in wind direction to
the north, northeast, wind gusts between 20 and 30 mph and rapidly
increasing waves to between 3 and 6 feet. This will result in
dangerous swim conditions for beaches from Sheboygan county
southward to Racine county. Will continue to monitor forecasts for
Kenosha county as they may need to be added to this risk.

Gagan

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Beach Hazards Statement...WIZ052 until 7 AM Wednesday.

     Beach Hazards Statement...WIZ060-WIZ066-WIZ071...7 PM Tuesday to
     7 AM Wednesday.

LM...Small Craft Advisory...LMZ643 until 7 AM Wednesday.

     Small Craft Advisory...LMZ644-LMZ645-LMZ646...7 PM Tuesday to 7
     AM Wednesday.

&&

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Hazardous Weather Outlook
National Weather Service Milwaukee/Sullivan WI
Issued by National Weather Service Chicago IL
431 PM CDT Tue Jul 6 2021

WIZ046-047-051-052-056>060-062>072-072145-
Marquette-Green Lake-Fond du Lac-Sheboygan-Sauk-Columbia-Dodge-
Washington-Ozaukee-Iowa-Dane-Jefferson-Waukesha-Milwaukee-
Lafayette-Green-Rock-Walworth-Racine-Kenosha-
431 PM CDT Tue Jul 6 2021

This Hazardous Weather Outlook is for portions of east central
Wisconsin, south central Wisconsin and southeast Wisconsin.

.DAY ONE...Tonight

Widely scattered thunderstorms are expected to develop this
afternoon and increase in coverage this evening, mainly over
areas north of the Interstate 94 corridor. These storms will pose
a risk for localized damaging wind gusts and small hail.

.DAYS TWO THROUGH SEVEN...Wednesday through Tuesday

Scattered thunderstorms are expected Wednesday with cloud to
ground lightning the main risk.

There are periodic chances for thunderstorms Friday into the
upcoming weekend.

.SPOTTER INFORMATION STATEMENT...

Spotter activation will not be needed.

LMZ643>646-072145-
Sheboygan to Port Washington WI-
Port Washington to North Point Light WI-
North Point Light to Wind Point WI-
Wind Point WI to Winthrop Harbor IL-
431 PM CDT Tue Jul 6 2021

This Hazardous Weather Outlook is for the nearshore waters from
Sheboygan Wisconsin to Winthrop Harbor Illinois.

.DAY ONE...Tonight

A Small Craft Advisory is in effect through early Wednesday for
rapidly increasing waves between 2 to 6 feet and a brief period of
north-northeast wind gusts up to 25 knots.

There is a chance for widely scattered thunderstorms this evening
with a risk for localized damaging wind gusts and small hail.

.DAYS TWO THROUGH SEVEN...Wednesday through Tuesday

Scattered thunderstorms are expected Wednesday with cloud to
ground lightning the main risk.

There are periodic chances for thunderstorms Friday into the
upcoming weekend.

LMZ080-261-362-364-366-563-565-567-669-671-673-675-777-779-868-
870-872-874-876-878-072145-
Lake Michigan Michigan City IN to St. Joseph MI 5 NM offshore to
mid-line of lake.-
Lake Michigan from Seul Choix Point to Rock Island Passage 5NM
offshore to Mid Lake-
Lake Michigan South of a line from Seul Choix Point to the
Mackinac Bridge and North of a line from Charlevoix MI to South
Fox Island 5NM offshore-
Lake Michigan from Charlevoix to Point Betsie MI 5NM Offshore to
mid lake-
Lake Michigan from Point Betsie to Manistee MI 5NM offshore to
Mid Lake-
Lake Michigan from Rock Island Passage to Sturgeon Bay WI 5NM
offshore to mid lake-
Lake Michigan from Sturgeon Bay to Two Rivers WI 5NM offshore to
Mid Lake-
Lake Michigan from Two Rivers to Sheboygan WI 5NM offshore to Mid
Lake-
Lake Michigan from Sheboygan to Port Washington WI 5NM offshore
to Mid Lake-
Lake Michigan from Port Washington to North Point Light WI 5NM
offshore to Mid Lake-
Lake Michigan from North Point Light to Wind Point WI 5NM
offshore to Mid Lake-
Lake Michigan from Wind Point WI to Winthrop Harbor IL 5NM
offshore to Mid Lake-
Lake Michigan from Winthrop Harbor to Wilmette Harbor IL 5NM
offshore to Mid Lake-
Lake Michigan from Wilmette Harbor to Michigan City in 5NM
offshore to Mid Lake-
Lake Michigan from Pentwater to Manistee MI 5NM offshore to Mid
Lake-
Lake Michigan from Whitehall to Pentwater MI 5NM offshore to Mid
Lake-
Lake Michigan from Grand Haven to Whitehall MI 5NM offshore to
Mid Lake-
Lake Michigan from Holland to Grand Haven MI 5NM offshore to Mid
Lake-
Lake Michigan from South Haven to Holland MI 5NM offshore to Mid
lake-
Lake Michigan from St Joseph to South Haven MI 5NM offshore to
Mid Lake-
431 PM CDT Tue Jul 6 2021

This Hazardous Weather Outlook is for the open waters of Lake
Michigan.

.DAY ONE...Tonight

A fast moving cold front will move north to south this evening
resulting in wind gusts to 25 knots and rapidly increasing waves
to between 3 and 7 feet, mainly across central and northern
portions of the lake.

Scattered thunderstorms tonight will pose a risk for localized
damaging wind gusts and small hail.

.DAYS TWO THROUGH SEVEN...Wednesday through Tuesday

Scattered thunderstorms are expected Wednesday over the central
and southern portions of the lake with cloud to ground lightning
the main risk.

There are periodic chances for thunderstorms Friday into the
upcoming weekend.

www.weather.gov/mkx

Special Weather Statement
National Weather Service MILWAUKEE/SULLIVAN WI
Issued by National Weather Service Chicago/Romeoville
145 PM CDT Tue Jul 6 2021

WIZ051-052-061945-
Sheboygan WI-Fond Du Lac WI-
145 PM CDT Tue Jul 6 2021

...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN FOND DU LAC AND
NORTHERN SHEBOYGAN COUNTIES UNTIL 245 PM CDT...

At 145 PM CDT, Doppler radar was tracking a strong thunderstorm near
Southern Lake Winnebago, or 10 miles northeast of North Fond Du Lac,
moving east at 35 mph.

Half inch hail and wind gusts up to 50 mph will be possible with this
storm.

Locations impacted include...
Sheboygan, Howards Grove, Elkhart Lake, Southern Lake Winnebago,
Mount Calvary, St. Cloud, Glenbeulah, Haven, Johnsonville, Pipe,
Calvary, Marytown and Johnsburg.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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.

If on or near Lake Winnebago, get out of the water and move indoors
or inside a vehicle. Remember, lightning can strike out to 10 miles
from the parent thunderstorm. If you can hear thunder, you are close
enough to be struck by lightning. Move to safe shelter now! Do not
be caught on the water in a thunderstorm.

&&

LAT...LON 4383 8841 4389 8841 4389 8840 4394 8840
      4394 8816 4389 8816 4389 8773 4381 8773
      4378 8771
TIME...MOT...LOC 1845Z 266DEG 28KT 4390 8831

Donofrio