862
FXUS63 KMKX 220355
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1055 PM CDT Sun Jun 21 2026

.KEY MESSAGES...

- Rain is gradually exiting from west to east for areas south of
  Interstate 94 tonight. Rain is expected to clear the state
  prior to sunrise.

- At least Moderate Swim Risk is expected for the Lake Michigan
  beaches Monday with the possibility for High Swim Risk to
  develop. Keep out of the water and away from dangerous areas
  like piers and breakwalls!

- Chances for thunderstorms Tue nt through Wed nt.

- Below normal temps continue.

&&

.SHORT TERM...
Issued 1055 PM CDT Sun Jun 21 2026

Today and Tonight:

A low pressure system in northeastern MO/central IL will
continue to move east toward the Mid Atlantic coast tonight. The
stratiform rain shield across the southern Great Lakes region
will continue to gradually shift east with the low bringing an
end to our rain tonight. Rain is already starting to end from
west to east yet tonight. Majority of the rain is expected to
end with in the next couple of hours. Some isolate light rain
could linger on the back side in the early morning hours, but by
and large all the rain will end prior to sunrise Monday. As this
low pressure system exits high pressure will be building in from
the Northern Plains. Skies will gradually begin to clear as the
stable air builds in and winds will become light. Lake shore
areas are expected to have the strongest winds of the day coming
off of lake Michigan which will keep temperatures cooler in the
low to mid 60s. Inland areas will be a bit warmer around the mid
70s. Scattered cumulus clouds are expected Monday afternoon
well inland from the lake. Dry conditions are expected to remain
through Monday night.

Patterson

&&

.LONG TERM...
Issued 1055 PM CDT Sun Jun 21 2026

Tuesday through Saturday:

An upper level trough will be descending down from southern Alberta
through the northern Plain and into the northern Great Lakes Region
late Tuesday. The sfc low will follow a very similar path and
is expected to cross through northern Wisconsin Wednesday. POPs
are expected to increase across the region from the northwest to
the southeast as this sfc low moves in. Instability should rise
across the state as a warm front moves through. This will bring
not only rain chances but also thunderstorms. The question
becomes how much instability and shear for any stronger to
severe storms. From some forecast soundings there looks to be
narrow CAPE and shear around 30 kts or more. So there is a
chance for storms, but each sounding that has both of these
features has a cap to contend with as well. So its looking like
this could be another conditional strong to severe storms
scenario as of now. This is still a couple of days out so things
could change, but a time period worth keeping an eye on.

For Thursday and Friday, there is some discrepancies around
500mb among guidance. Some build in ridging aloft faster than
others. High pressure is expected to move into the Great Lakes
Region briefly but timing and whether or not there could be some
lingering PVA aloft is still in question. The PVA aloft with
high pressure near the sfc has some low chance POPs (10-30%)
mixing in for both Thursday and Friday at times. Available
moisture and any forcing at the sfc will really be the catalyst
for any light rain during this time (a lake breeze could be just
enough forcing, convergence at the sfc, to get light rain).
Hard to tell if this will even be an issue if the upper level
ridge is in place aloft.

Next decent chance for rain looks to come Sunday into Monday as
a trough moves through the western CONUS toward the Great Lakes
Region. With there already being discrepancies in the 500mb
flow prior to this, models are just continuing to diverge from
each other further. Granted timing and strength seem to be the
biggest problems so POPs are still hitting a peak of 40-60%
Monday.

Patterson

&&

.AVIATION...
Issued 1055 PM CDT Sun Jun 21 2026

MVFR to VFR conditions are expected through the period.
Widespread along and south of the interstate 94 corridor will
slowly end from west to east this evening into tonight. MVFR
ceilings around 1-3 kft will be possible within the exiting rain.
Visibilities are expected to be 6 SM or higher for any terminal
experiencing rain. Terminals north of interstate 94 are
expected to stay dry with largely VFR conditions. Overcast skies
are expected to persist across southern Wisconsin until Monday
morning. Mid to high level clouds will start to clear from the
northwest to the southeast around sunrise Monday morning. Partly
cloudy skies are expected Monday with some diurnal cumulus
clouds around 4-6 kft. There is some uncertainty in how
expansive any diurnal cumulus clouds could become.

The lingering light southerly winds will eventually turn to
easterly then become light and variable by around midnight
tonight. Light east to northeast wind are expected to Monday.
Winds are expected to be at their strongest along Lake Michigan
with sustained wind around 10-15 kts and gusts up to 20 kts.
Light and variable winds are expected again Monday night.

Patterson

&&

.MARINE...
Issued 1055 PM CDT Sun Jun 21 2026

Low pressure around 29.7 inches will track eastward from
northeastern Missouri to Ohio by Monday. Light easterly winds will
persist across much of the lake with breezy northeast winds across
the southern third tonight through Monday. As the low departs
and high pressure moves in the pressure gradient will tighten
just enough to build waves across the southern Wisconsin
nearshore. Waves are expected to be around 4 feet at time
Monday afternoon. A Small Craft Advisory is in effect for the
elevated waves for areas south of Lighter northerly winds are
expected late Monday evening into Tuesday as high pressure
around 30.1 inches builds into the region. Winds will become
light and variable Tuesday night as the high pressure tracks
overhead. By Wednesday, the high pressure will exit to the
southeast and low pressure around 29.8 inches moves from the
northern Plains into northern Wisconsin. As the low approaches
breezy south to southeast winds will develop across the lake.

Patterson

&&

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

$$

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