391
FXUS63 KMKX 221943
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
243 PM CDT Fri Aug 22 2025

.KEY MESSAGES...

- Widely scattered showers and a few storms tonight into early
  Saturday morning with a cold front.

- Much cooler, less humid and breezy from later Saturday into
  early next week.

- Some waterspouts are possible Sunday into Monday across the
  northern portions of Lake Michigan.

&&

.SHORT TERM...
Issued 243 PM CDT Fri Aug 22 2025

Tonight through Saturday night:

A cold front will push southeast across the area mainly later
tonight into early Saturday morning, exiting the far southeast
by later in the morning. There is weak instability (less than
500 J/kg of mean layer CAPE) and modest at best upward vertical
motion with the front. CAMs continue to show widely scattered
showers and a few thunderstorms possible with the frontal
passage, which seems reasonable. Will keep PoPs around 20
percent for this activity in the forecast for mainly later
tonight into early Saturday morning.

West northwest winds are expected behind the front Saturday
afternoon and night, and will become brisk, as the pressure
gradient tightens with the deepening low well to the northeast
of the region. This will allow for cold air advection to develop
and begin to bring in cooler temperatures. Saturday should
still have highs in the lower to middle 70s, before lows drop
into the lower to middle 50s for Saturday night. In addition,
stratocumulus clouds within the developing cyclonic flow at 500
mb should develop, as several vorticity maxima rotate through
the region.

Wood

&&

.LONG TERM...
Issued 243 PM CDT Fri Aug 22 2025

Sunday through Friday:

The 500 mb low will remain to the northeast of the region Sunday
into Tuesday, allowing for cyclonic flow to linger over the
region. Several vorticity maxima will rotate through at times,
with forecast soundings showing stratocumulus clouds and perhaps
scattered showers at times. Temperatures will be much colder, as
cold air advection continues on brisk west northwest winds.
Highs should be in the middle 60s to around 70 each day, with
lows in the middle to upper 40s away from the lake. These values
have been well supported by the NBM and ensemble trends over the
past several days.

The 500 mb low will gradually weaken later in the week, allowing
for a ridge axis to slowly shift east across the northern
Plains. This should allow temperatures to slowly modify closer
to seasonal normal values by the end of the week. There may be
some precipitation possible in the middle or later portions of
the week, though it is too uncertain at this time to mention in
the forecast.

Wood

&&

.AVIATION...
Issued 243 PM CDT Fri Aug 22 2025

Expect scattered to broken cumulus with 3500 to 4000 foot AGL
bases into this evening, with some high clouds moving through as
well. Light southwest winds are expected, though a southeast
lake breeze may try to reach the Milwaukee and Kenosha terminals
by 00Z Saturday.

A cold front will push southeast across the area mainly later
tonight into early Saturday morning, exiting the far southeast
by later in the morning. Widely scattered showers and a few
thunderstorms are possible with the frontal passage.

West northwest winds are expected behind the front Saturday
afternoon and night, and will become gusty at times. In
addition, scattered to perhaps broken stratocumulus clouds in
VFR category should develop.

Wood

&&

.MARINE...
Issued 243 PM CDT Fri Aug 22 2025

High pressure around 30.1 inches will linger today and begin
weakening. South to southwest winds are expected across the lake
today, becoming breezy across the northern two thirds of the
open waters this afternoon. A strong cold front will then move
northwest to southeast tonight into Saturday morning. Expect
widely scattered showers and a few thunderstorms along this
front.

Winds shift to become west northwest and brisk Saturday through
Monday, as low pressure strengthens to around 29.5 inches in
northeastern Ontario. Winds may reach Small Craft Advisory
levels at times Saturday afternoon into early next week.

There will be a potential for waterspouts across the northern
half of the lake Sunday and Monday, as enough low level
instability with favorable delta T values within the cyclonic
flow aloft help support the waterspout risk. This risk may
spread across the southern half of the lake as well.

Wood

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...None.
&&

$$

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