382
FXUS63 KMKX 050831
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
331 AM CDT Sat Jul 5 2025

.KEY MESSAGES...

- Showers and thunderstorms are expected this afternoon through tonight.
  A few storms could produce gusty winds and locally heavy
  rainfall.

- Hot and muggy conditions continue this afternoon, with heat indices
  in the low to mid 90s.

- Small Craft Advisory remains in effect this afternoon in all nearshore
  zones.

- Periods of moderate swimming risk remain forecast this
  afternoon at Sheboygan County beaches.

- Poor air quality expected near Lake Michigan today.

- Humidity returns Tuesday through the end of the week, with
  periods of showers and thunderstorms also returning.

&&

.SHORT TERM...
Issued 332 AM CDT Sat Jul 5 2025

Today through Sunday:

Synopsis/Mesoanalysis: Upper ridging remains centered from the mid-
Mississippi Valley to Lake Huron early this morning, resulting in
mostly clear skies across southern Wisconsin. A sampling of regional
ACARS and model soundings depicts a steep nocturnal inversion just
off the surface, which has allowed pockets of haze to form where 1)
temperatures have cooled to still very muggy dew point temperatures
and 2) where smoke has lingered following last evening`s firework
shows. The aforementioned haze will gradually improve through the
predawn hours, with any lingering visibility reductions improving by
sunrise. Currently being analyzed over South Dakota, an area of low
pressure will progress into the Upper Mississippi Valley this
afternoon, reaching the Upper Peninsula of Michigan tonight. The
low`s approach will result in increasing southwest winds this
afternoon, allowing for another hot and humid day across southern
Wisconsin. The low will pull a cold front across the region this
afternoon and evening, encouraging shower and thunderstorm
development areawide. Widespread severe weather is not anticipated
in this activity, though a few stronger storms with gusty winds and
small hail can`t be ruled out. Heavy downpours will be possible in
storms, which could lead to minor urban/small stream flooding & some
rises on area rivers. The aforementioned cold front should clear the
majority of southern Wisconsin by Sunday morning, but may linger
through early afternoon across the east. Thus can`t rule out
additional scattered showers and storms across east-central and
southeastern Wisconsin Sunday morning and afternoon.

Today: Another hot and humid day is anticipated with southwest winds
persisting across the area. Combined temps and dew points will lead
to widespread heat indices in the low to mid 90s, with pockets of
upper 90s readings possible across southeastern Wisconsin. Be sure
to wear light-colored & loose-fitting clothing, drink plenty of
water, and take breaks in the shade or air conditioning if planning
to be outdoors today. The gusty winds allow for elevated wave
heights at Sheboygan County beaches, where periods of moderate
swimming risk conditions are forecast. Anticipate areas of shower
and thunderstorm development during the afternoon hours across the
western half of the area as a cold front encroaches. Expect storm
organization to be marginal at best given largely front-parallel
wind shear at/below 20 knots, though a few stronger wind gusts can`t
be ruled out in downdrafts given a very unstable environment. Pre-
frontal precipitable waters in the 1.75-2.0"+ range (2-2.5 standard
deviations above early July climo) will allow for torrential
downpours in thunderstorms, which could lead to minor urban & small
stream flooding & rises on area rivers. Said impacts will be most
likely in areas experiencing training or multiple rounds of showers
and storms. Stay weather aware if planning to be outside this
afternoon, and move indoors if a storm approaches your area.

Tonight: Showers and storms will continue to spread east into the
remainder of the region. Anticipate that severe potential will
gradually wane following sunset & the loss of surface heating,
though heavy downpour potential will continue given the anomalously
moist environment in place. Will thus be monitoring for additional
minor hydro impacts through tonight, particularly in any areas of
training storms.

Sunday: With the front clear of most of the area, "cooler"
temperatures in the 80s are forecast. Can`t rule out additional
showers and storms through mid-afternoon across east-central and
southeast Wisconsin, where the frontal boundary could linger.

Quigley

&&

.LONG TERM...
Issued 332 AM CDT Sat Jul 5 2025

Sunday night through Friday:

Any remaining showers will end by Sunday night, with northerly to
northwesterly flow bringing cooler temperatures back to the region.
Expecting lows around 60 degrees.

Temperatures return to near normal values (lower 80s) on Monday,
with dry conditions expected within surface high pressure centered
over southeastern Ontario.

High pressure breaks down into Tuesday as ridging builds back into
the Great Plains, with multiple shortwaves traveling around the top
of the ridge into the Upper Midwest. Timing and placement for each
round of showers and storms will be dependent on upstream convection
the previous time periods, but most confidence exists in Tuesday
evening into Tuesday night (30 to 45 percent chance), as well as on
Friday (30 percent chance) as these are the main timeframes that see
a larger shortwave phasing with surface low pressure systems.
However, daily thunderstorms are not out of the question, and kept
NBM probabilities through the long range time period.

MH

&&

.AVIATION...
Issued 332 AM CDT Sat Jul 5 2025

Predominantly VFR conditions prevail early this morning under mostly
clear skies. Occasional HZ and attendant lower VIS readings have
been reported at several observation sites, resulting in brief
periods of MVFR flight categories. Have accounted for this potential
with TEMPO groups in the 06Z/09Z updates at JVL, MKE, and SBM,
where VIS reductions have been most persistent. Expect
conditions to gradually improve by the predawn hours, but will
nevertheless monitor trends for potential changes. Surface low
pressure will approach from the Northern Plains today, resulting
in gusty south-southwest winds from late morning into the
afternoon hours. Said low will drag a cold front across southern
Wisconsin during the late afternoon and evening hours, with
multiple rounds of -SHRA and -TSRA possible. Have accounted for
said multiple periods of precip potential, highlighting the
highest- confidence timing windows with prevailing thunder
groups. Expect -SHRA and -TSRA to gradually taper tonight as
the responsible cold front pushes east. Anticipate MVFR to IFR
to settle in with precip this evening, persisting through the
conclusion of the period at all aerodromes.

Quigley

&&

.MARINE...
Issued 332 AM CDT Sat Jul 5 2025

Currently positioned over the northern Great Plains, 1008 mb low
pressure will shift into the western Great Lakes today, resulting in
increasing southerly gusts across Lake Michigan. Said low will
progress across Michigan`s Upper Peninsula this evening, dragging a
cold front across the open waters in the process. Areas of showers
and thunderstorms are expected along and ahead of the front.
Widespread severe weather is not anticipated, though a few strong
storms with gusty winds are possible. The front will linger near or
just east of Lake Michigan during the day on Sunday, with additional
showers and scattered thunderstorms possible through the afternoon
hours. Precipitation will taper by Sunday evening as the cold front
moves into the Ohio River Valley. North to northwest winds will
become established across all of the open waters behind the front
by early Sunday evening.

1016 mb high pressure will approach Lake Michigan during the day on
Monday, resulting in fair conditions and weakening northerly winds.
The high will cross the open waters Monday evening and night,
resulting in light and variable winds. Generally light and variable
winds will continue through mid-week as a second area of 1020 mb
high pressure lingers across the western Great Lakes. Periods of
showers and embedded thunderstorms return to the open waters Tuesday
through late week as humidity builds back into the Upper Midwest.

Gusty winds and elevated wave heights are expected in nearshore
zones today as low pressure approaches from northern Great
Plains. A Small Craft Advisory remains in effect between 1-8 PM
CDT from Sheboygan south to Winthrop Harbor. Showers and
thunderstorms will move into nearshore zones this evening and
tonight as a cold front crosses Lake Michigan. While widespread
severe weather is not anticipated, a few stronger storms could
produce gusty winds. Additional showers and isolated storms are
possible Sunday morning and afternoon from North Point south to
Winthrop Harbor, with conditions drying out Sunday evening into
Monday. Additional periods of showers and storms are forecast
Tuesday afternoon through late week.

Quigley

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646...1 PM
     Saturday to 8 PM Saturday.

&&

$$

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