287
FXUS63 KMKX 211754
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
1254 PM CDT Mon Sep 21 2026

.KEY MESSAGES...

- A prolonged period of high swim risk conditions continues into
  early Wednesday evening for all beaches along Lake Michigan.

- Scattered light rain showers are expected roughly along and
  west of a line from Madison to Janesville this evening into
  early Tuesday.

- Below normal temps are expected for the first
  half of the week, with gradually warming temps into the
  weekend.


&&

.SHORT TERM...
Issued 1254 PM CDT Mon Sep 21 2026

Tonight through Tuesday night:

Latest guidance continues to show shower chances this evening
into early Tuesday as a weakening shortwave moves through.
Soundings show plenty mid and upper level moisture, so how much
rain makes it to the ground will depend on how much the low
levels saturate. Overall, the lower levels are looking more
saturated per latest models compared to 24 hours ago. Based on
this and upstream radar, have bumped up the precip chances
roughly from Madison to Janesville and westward. Farther east,
the lower levels will likely remain drier due to the influence
of strong surface high pressure centered near the Ontario/Quebec
border. Thus kept the forecast dry in the east/northeast,
though a few sprinkles are possible. Temps tomorrow will be
several degrees below normal again given the cooler airmass in
place and expected mostly cloudy skies much of the day as the
wave slowly exits.

The Beach Hazards Statement remains in effect until 7 PM CDT
Wednesday evening for all Lake Michigan beaches, with persistent
gusty east northeast winds and high waves of 4 to 8 feet. Stay
out of the water, and away from dangerous areas like piers and
breakwalls.

DDV

&&

.LONG TERM...
Issued 1254 PM CDT Mon Sep 21 2026

Wednesday through Monday:

Strong high pressure centered just north of the eastern Great
Lakes early Wednesday will largely remain in place the second
half of the week while gradually weakening. Meanwhile, upper
level ridging will attempt to build in from the west through
late week. Models still differ as to whether southern Wisconsin
will be more under the influence of the departing troughing
pattern or the approaching ridge by the end of the week into the
weekend. Thus there remains some uncertainty with temps during
this period, though an overall slight warming trend looks
likely. Additionally, models suggest a shortwave may come over
the top of the ridge late week or during the weekend, bringing
shower chances back to the area. As with temps, there is still
uncertainty with the timing of any precip given the differences
with the trough/ridge among models.

DDV

&&

.AVIATION...
Issued 1254 PM CDT Mon Sep 21 2026

Latest guidance continues to show shower chances this evening
into early Tuesday as a weakening shortwave moves through. The
best chance for rain will be from Madison to Janesville and
westward. Will continue to monitor upstream radar and bump up
precip chances in the forecast and TAFs as needed. Farther
east, the lower levels will likely remain drier due to the
influence of strong surface high pressure centered near the
Ontario/Quebec border. Thus kept the forecast dry in the
east/northeast, though a few sprinkles are possible.

Ceilings will likely continue to improve from northeast to
southwest the remainder of the day, with mainly VFR conditions
expected across southern Wisconsin by early evening. Ceilings
will then largely be in the 5-10 kft range tonight into Tuesday,
with decreasing clouds likely in the afternoon.

Breezy east to northeast winds will persist this afternoon
through Tuesday, though will be a little lighter during the
evening and overnight hours.

DDV

&&

.MARINE...
Issued 1254 PM CDT Mon Sep 21 2026

High pressure around 30.4 inches north of Lake Superior today
will shift eastward into Quebec tonight. The high will then
largely remain in place through the middle of the week, while
strengthening to around 30.7 inches by Wednesday morning. Gusty
east to northeast winds are expected today through Wednesday.
Winds then look to diminish toward the end of the week, as the
high pressure system slowly weakens and moves farther east.

DDV

&&

.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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