Flood in Wisconsin, April 1 to 3, 2025

Area Forecast Discussion...UPDATED
National Weather Service Milwaukee/Sullivan WI
945 PM CDT Mon Mar 31 2025

.KEY MESSAGES...

- A quick hit of accumulating snow is expected Tuesday evening
  across central Wisconsin. Moderate rates may result in travel
  impacts.

- Thunderstorms late Tuesday night/Wednesday morning may
  produce hail. Additional storms are possible Wednesday
  afternoon with an associated severe risk, *if* enough
  instability is able to form. This is very uncertain.

- Relatively cool and quiet weather expected for the end of the
  week into the weekend.

&&

.UPDATE...
Issued 945 PM CDT Mon Mar 31 2025

Weak high pressure will move across the area overnight and to
the east on Tuesday. Some lower clouds may linger in far eastern
areas into the overnight hours. Winds will continue to weaken
overnight, with lows in the middle 20s in south central
Wisconsin, to the upper 20s closer to Lake Michigan.

Wood

&&

.SHORT TERM...
(Issued 256 PM CDT Mon Mar 31 2025)

Tonight through Wednesday:

Northerly breezes will continue into this evening, with
temperatures recovering into the 40s under plenty of sunshine
this afternoon. High pressure noses into the area tonight,
bringing light and variable winds through the overnight hours.
Expecting lows in the mid to upper 20s. Low pressure deepens and
ejects into Tuesday morning, shifting winds to become steady
and southeasterly into the day Tuesday.

As low pressure lifts into the Great Lakes region, a warm
frontal feature is expected to lift northward through southern
Wisconsin, bringing potential for a rain and snow mix Tuesday
afternoon into Tuesday night. Going into later Tuesday evening
as temperatures drop and rain transitions entirely to snow, the
front is expected to be sitting across central Wisconsin,
bringing potential for around an inch of snowfall (40 to 60
percent chance of an inch or more) from northern Sauk County
through northern Washington County and much of Sheboygan County
northward. The front eventually lifts north and away into the
late overnight hours, and simultaneously are expecting
southeasterly winds to bring in temperatures above freezing late
Tuesday night into early Wednesday morning.

12Z modeling indicates potential for a brief period of MUCAPE
around 500 J/kg to build into southern Wisconsin Wednesday
morning. This in additional to 850 mb frontogenesis and the
large scale synoptic lift from the approaching surface low could
lead to rounds of thunderstorms moving west to east across
southern Wisconsin. A few of these storms could produce hail,
but generally not anticipating strong enough vertical
development to produce widespread severe thunderstorms.

Significant uncertainty remains in the Wednesday afternoon
timeframe relative to severe thunderstorm potential.
Southeasterly flow off Lake Michigan will prevent significant
WAA at the surface, although expectations for a general, slow
warming trend remain in place. This gives the potential for
lacking instability and keeping a surface inversion, thus
preventing surface based thunderstorms. That being said, a
strong low level jet around 50 kt from the southwest at 850 mb
combined with marginal MUCAPE and surface to 3 km shear close to
55 kt could lead to an isolated bowing segment breaking through
the stable layer (especially if a break of sun occurs during
the early afternoon hours during a brief dry slot window) and
producing gusty winds. Regardless, low pressure occludes and
swings northward by Wednesday evening, with its cold front
moving offshore into Lake Michigan by Wednesday evening as well.

MH

&&

.LONG TERM...
Issued 256 PM CDT Mon Mar 31 2025

Wednesday Night through Monday:

Relatively quiet and cool weather is expected for the remainder
of the week and into the weekend, with high pressure expanding
across the Northern Plains Thursday. The frontal boundary
associated with Wednesday's system will stall out across the
Ohio Valley for the latter portion of the workweek, with several
rounds of rain across that area as various shortwaves eject
eastward from the Southwestern US. Right now it looks like the
front will be far enough south to keep any meaningful
precipitation well south of the area.

A stronger shortwave will pass through the area late in the
weekend, which may bring additional low end (20-30%) chances for
precipitation.

Boxell

&&

.AVIATION...
Issued 945 PM CDT Mon Mar 31 2025

Winds will continue to weaken overnight as high pressure moves
across the region. Some scattered to broken ceilings around 3500
to 4000 feet AGL may linger at the terminals near Lake Michigan
overnight.

Winds will shift to the east southeast on Tuesday and gradually
increase through the day and into Tuesday night. Gusty winds
are expected later in the afternoon into Tuesday night. Low
level wind shear may occur as well by later Tuesday night.

Middle to high clouds will gradually shift east into the area on
Tuesday, lower steadily to around 1500 feet AGL by later Tuesday
evening, then to around 500 feet AGL toward Wednesday morning.
Visibility will drop to 2 to 4 miles with the rain/snow mix or
all light snow Tuesday night, perhaps lower at times in northern
parts of the area.

The precipitation should become mainly rain later Tuesday night
into Wednesday morning from south to north. Wet, slushy snow
accumulations of around an inch may occur in Sheboygan and far
northern portions of the area, but rates will be under one
quarter inch per hour. May see a few thunderstorms occur toward
Janesville and Kenosha toward early Wednesday morning as well.

Wood

&&

.MARINE...
(Issued 945 PM CDT Mon Mar 31 2025)

High pressure around 30.1 inches will move across the region
overnight and to the east on Tuesday, with north winds shifting
to the east.

Strong low pressure around 29.1 inches will develop in the
Central High Plains Tuesday, then shift northeast into northwest
Iowa Tuesday night and west central Wisconsin on Wednesday.
This should bring gusty southeasterly winds Tuesday night into
Wednesday, with gales possible.

A Gale Watch remains in effect for most of this period for the
nearshore waters and open waters of the lake. A Small Craft
Advisory will be needed ahead of the Gale Watch for the
nearshore waters Tuesday evening, and later Wednesday afternoon
into Wednesday night.

The low will then move across western Lake Superior Wednesday
night and into Ontario on Thursday. Gusty winds will shift to
the southwest Wednesday night and west on Thursday, gradually
weakening.

Thunderstorms are possible Tuesday night across the southern
portions of the lake, and across the entire lake Wednesday into
Wednesday evening. A few storms may be strong to severe during
this period.

MH/Wood

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Gale Watch...LMZ080-LMZ366-LMZ565-LMZ567-LMZ643-LMZ644-LMZ645-
     LMZ646-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868-
     LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...1 AM Wednesday to 1
     PM Wednesday.

     Gale Watch...LMZ261-LMZ362-LMZ364-LMZ563...7 AM Wednesday to 4
     PM Wednesday.

&&

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Hazardous Weather Outlook...UPDATED
National Weather Service Milwaukee/Sullivan WI
926 PM CDT Mon Mar 31 2025

WIZ046-047-051-052-056>060-062>072-020230-
Marquette-Green Lake-Fond du Lac-Sheboygan-Sauk-Columbia-Dodge-
Washington-Ozaukee-Iowa-Dane-Jefferson-Waukesha-Milwaukee-
Lafayette-Green-Rock-Walworth-Racine-Kenosha-
926 PM CDT Mon Mar 31 2025

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

.DAY ONE...Tonight

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...Tuesday through Monday

A rain and snow mix is expected to push southwest to northeast
Tuesday evening into Tuesday night, with up to an inch of
accumulation across central Wisconsin.

Chances for thunderstorms develop along the Illinois and
Wisconsin border early Wednesday morning, with a line of storms
expected to move west to east across southern Wisconsin Wednesday
afternoon and evening. A few storms may be strong to severe.

.SPOTTER INFORMATION STATEMENT...

Spotter activation may be needed on Wednesday into Wednesday
evening.

LMZ643>646-020230-
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-
926 PM CDT Mon Mar 31 2025

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

.DAY ONE...Tonight

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...Tuesday through Monday

Gusty easterly winds and high waves are expected Tuesday evening
through Wednesday. Small Craft Advisories will be needed during
this time frame. Gales are possible late Tuesday night through
Wednesday morning, and a Gale Watch is in effect.

Thunderstorms are possible early Wednesday morning south of Wind
Point, and again Wednesday afternoon and evening across the
nearshore waters. A few storms may be strong to severe.

LMZ080-261-362-364-366-563-565-567-669-671-673-675-777-779-868-
870-872-874-876-878-020230-
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-
926 PM CDT Mon Mar 31 2025

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

.DAY ONE...Tonight

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...Tuesday through Monday

Gusty east to southeast winds will develop Tuesday night and
continue into Wednesday. Gales are possible, and a Gale Watch is
in effect for most of this period.

Thunderstorms are possible across the southern portions of the
lake early Wednesday morning, and across the entire lake
Wednesday afternoon and night. A few storms may be strong to
severe.

Wood
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