180
FXUS63 KMKX 210500
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1200 AM CDT Mon Sep 21 2026

.KEY MESSAGES...

- A prolonged period of high swim risk conditions continues
  through the start of the week for all southern WI beaches.

- Mostly dry weather and below normal temps for the first half
  of the week with gradually warming temps into the weekend.

&&

.SHORT TERM...
Issued 1200 AM CDT Mon Sep 21 2026

Today through Tuesday:

High pressure meandering over/just north of the Great Lakes
region and persistent east to northeasterly flow will continue
to dominate the weather pattern across southern WI for the
start of the week. This should keep temps fairly seasonal with
daily highs in the 60s, while nightly lows dip into the upper
40s and low 50s. Any cloud cover could keep the overnight temps
a few degrees warmer than the current forecast, but nonetheless
will see fall-like lows to start the week.

As for precip chances, the +1030mb high centered to the
northeast looks to bring plenty of dry air and subsidence to the
area. However, continue to see a signal on the 00z models of
500mb shortwave trough traversing the Dakotas today and making
its way into the Midwest on Tuesday. While these two features
will compete with each other, cannot completely rule out seeing
the shortwave trough pair with PWATs around 1 inch and
additional moisture off of Lake Michigan to be enough to spur
sporadic sprinkles/drizzle later today into Tuesday morning
across southern portions of the CWA, especially toward the WI/IL
border where cloud cover is most likely. Overall if this
scenario pans out, any activity may not be measurable (>0.01
inch), but could still bring a period of damp, misty, and dreary
conditions into the first half of Tuesday. Once the shortwave
trough treks east, then the high pressure dominance takes a
firmer hold over the area.

Lastly with the persisting breezy onshore flow over the past
and upcoming days, waves up to 4-9 ft are expected to continue
through Tuesday. Thus resulting in high swim risk conditions
for all Southern WI beaches over the next few days.

Wagner

&&

.LONG TERM...
Issued 1200 AM CDT Mon Sep 21 2026

Wednesday through Sunday:

The stronger high pressure continues to influence the pattern
through midweek, but will gradually shift east and winds are
progged to lessen. While high swim risk conditions linger into
Wednesday, these conditions should begin to ease into Thursday.
Otherwise, upper-level ridge is progged to build into the Upper
Midwest through the second half of the week. Expect mostly dry
conditions and gradually warming high temps each day into the
weekend.

Wagner

&&

.AVIATION...
Issued 1200 AM CDT Mon Sep 21 2026

Expect ceiling conditions bouncing between VFR/MVFR levels
tonight with breezy northeasterly winds. Eventually expecting
gusts along the lakeshore to ease, but still looking breezy
through day the morning. Otherwise, breezy easterly winds look
to pick up again through the late morning and persist through
the afternoon. Some lower ceilings may linger along the WI/IL
border this morning, but ceilings are expected to lift from
north to south as high pressure builds down into the Great
Lakes region for the start of the week.

Wagner

&&

.MARINE...
Issued 1200 AM CDT Mon Sep 21 2026

Building high pressure meandering over/just north of the Great
Lakes will keeping breezy northeast to easterly flow through
midweek. Thus resulting in elevated wave heights and small craft
conditions through at least Wednesday. Given the tighter
pressure gradient also could not rule out sporadic, brief gale
force gusts across central and southern portions of Lake
Michigan through today. Otherwise, winds gradually diminish for
the second half of the week as the high pressure weakens and
pushes further east.

Wagner

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Beach Hazards Statement...WIZ052-WIZ060-WIZ066-WIZ071-WIZ072
     until 7 PM Wednesday.

LM...Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646 until 7 PM
     Wednesday.

&&

$$

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