157
FXUS63 KMKX 210609
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
109 AM CDT Tue Jul 21 2026

.KEY MESSAGES...

- Drier & less humid through the end of the work week. Muggy
  conditions return late weekend.

- Showers & storms return to the forecast Saturday into Sunday.

&&

.SHORT TERM...
Issued 100 AM CDT Tue Jul 21 2026

Today through Wednesday:

A cold front will continue southward across the region predawn
this morning, with gusty NW winds arriving behind it post-dawn.
20-30 MPH gusts are expected at times through the daytime hours.
Highs in the low 80s expected. The latest CAMs suggest that a
sprinkle of rain cannot be completely ruled out from some open-
cellular showers beneath the strong subsidence inversion, we can
limit the odds of any measurable precip to 15% or less.

Even cooler and more pleasant conditions forecast for Wednesday,
highs in the 70s and dewpoints around 50 (noticeably drier
air). High pressure passes directly overhead, with mostly sunny
skies and dry weather.

Sheppard

&&

.LONG TERM...
Issued 100 AM CDT Tue Jul 21 2026

Wednesday night through Sunday:

Synopsis: High pressure will linger over the western Great Lakes
through Thursday, maintaining a cooler and dry weather pattern. The
high will shift east Friday into Saturday, allowing for southerly
winds and steadily climbing surface temperatures through the
weekend. Increasing humidity will eventually accompany the rising
temperatures, though its arrival will lag behind that of the warmer
air temperatures. More humid conditions will thus hold off until
Saturday night into Sunday. With warmer temperatures & humidity
attempting to work back into the area, shower and thunderstorm
chances return to the forecast Saturday night into Sunday.

Saturday through Sunday: The next period of potential weather
impacts arrives following a quiet end to the work week. Impacts
could come from a combination of increasing humidity & heat indices
on Sunday, in addition to chances for showers and thunderstorms
Saturday night into Sunday. Finer details---namely if heat indices
will approach headline thresholds and/or if any storms could be
strong/severe---will be refined as trends clarify through the end of
this week, though initial indications are that clouds & limited air
mass residence time will keep temps & heat indices below headline
levels. Any stronger storm potential will depend on timing, the
details of which remain murky this far out. Will provide more
updates as this portion of the period draws closer.

Quigley

&&

.AVIATION...
Issued 100 AM CDT Tue Jul 21 2026

A west breeze continues across the region predawn this morning,
with gusty northwest winds arriving behind a cold front shortly
after sunrise. Roughly 20-25kt wind gusts expected through the
daytime hours, tapering down into tonight.

Predominantly dry and VFR conditions expected through the TAF
period. Some lingering instability over far southern WI could
yield a stray shower or perhaps even a thunderstorm over the
next few hours.

Diurnal cumulus clouds between 3,500 and 6,000 ft gradually
build into the region from the northwest later this morning, and
we could even see a trace (sprinkle) of rain from them this
afternoon. Chances for measurable rainfall are 15% or less for
now, so have excluded this activity from the TAF for now. A
PROB30 group for 6SM SHRA may suffice in a future issuance.

Sheppard

&&

.MARINE...
Issued 100 AM CDT Tue Jul 21 2026

Low pressure around 29.3 inches will track eastward across James
Bay through today, with high pressure of 30.1 inches resting
over central Saskatchewan and Manitoba. Winds will veer from
southwest to northwest through this morning and remain breezy as
a cold front crosses Lake Michigan. Gusty north winds then
arrive late this afternoon into tonight, with a few gusts to
gale force possible. Winds are expected to gradually weaken by
Thursday, as high pressure around 30.2 inches builds into the
Great Lakes region.

Sheppard

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Beach Hazards Statement...WIZ052-WIZ060 until 7 AM Tuesday.

LM...Small Craft Advisory...LMZ643-LMZ644 until 7 AM Wednesday.

     Small Craft Advisory...LMZ645-LMZ646 until 4 PM Wednesday.

&&

$$

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