593
FXUS63 KMKX 202047
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
247 PM CST Sat Dec 20 2025

.KEY MESSAGES...

- Blustery and cold conditions are expected tonight, with wind
  chills falling below zero later tonight into Sunday morning.

- Chances (about 20 to 40 percent) for light snow later Sunday
  night into Monday morning, mainly north of the Interstate 94
  and Highway 18 corridor. Any snow accumulations may remain
  north of the area.

- Temperatures continue to trend well above normal Tuesday
  through Christmas Day.

&&

.SHORT TERM...
Issued 247 PM CST Sat Dec 20 2025

Tonight through Monday:

The cold front will push to the east of the area by sunset,
with clear skies and gusty west to northwest winds behind it.
This will bring in cold air advection and falling temperatures,
which will continue into tonight. Lows tonight should bottom out
in the single digits above zero, with wind chills later tonight
and Sunday morning in the single digits below zero to around 10
below zero. The coldest values will be in the northern parts of
the area.

High pressure passing by to the southwest of the area later
tonight into Sunday should bring dry conditions, clear skies
and gradually weakening winds. Highs Sunday will be in the lower
to middle 20s.

Warm air advection will develop Sunday night into Monday, as
winds begin to increase out of the south. Forecast soundings are
showing saturation developing above 800 mb later Sunday night
into Monday morning, but remaining quite dry below it. A band of
850 mb to 700 mb frontogenesis response shifts northeast
through the area during this period, though the best upward
vertical motion appears to be more in central and northern
Wisconsin.

For now, kept the general 20 to 40 percent chances for light
snow in northern portions of the area, though it may trend more
to the north per ensemble output of measurable and greater than
or equal to 0.10 inches of QPF. It appears most of the snow
accumulations may remain to the north as well.

There may be some lingering low level moisture Monday afternoon
within weak warm air advection and lighter south winds. The
layer above the low levels dries out, so there may be some ice
crystal loss and possible drizzle (or freezing drizzle if
surface temperatures drop to or below freezing).

As of now, it appears temperatures should remain above
freezing. Kept small chances for light snow and light rain for
now in the afternoon in northeast parts of the area. May need to
add in some drizzle in later forecasts. Highs should rise into
the middle to upper 30s Monday afternoon.

Wood

&&

.LONG TERM...
Issued 247 PM CST Sat Dec 20 2025

Monday night through Saturday:

Some light drizzle may linger into Monday night, as weak warm
air advection and low level moisture lingers.

A general ridge axis at 500 mb should build over the Northern
Plains into the Upper Midwest Monday night into Christmas Day.
Ensembles suggest that this trend will favor well above normal
temperatures to work into the region Tuesday into Christmas Day,
with Christmas Day the warmest. Highs may reach to near or above
50 degrees toward the Wisconsin/Illinois border on Christmas
Day.

There are some hints at a low pressure system moving northeast
through southern Wisconsin or northern Illinois later on
Christmas Day. Any precipitation looks to be rain at this point
with the warm temperatures. Cooler but still above normal
temperatures should linger Friday into next weekend.

Wood

&&

.AVIATION...
Issued 247 PM CST Sat Dec 20 2025

The cold front will push to the east of the area by sunset, with
clearing skies. Gusty west to northwest winds behind front are
expected into tonight.

High pressure passing by to the southwest of the area later
tonight into Sunday should bring dry conditions, clear skies
and gradually weakening winds. Winds will begin to increase out
of the south tonight.

Any light snow appears to remain north of the area later Sunday
night into Monday morning, though Sheboygan may see a little bit
of this activity. Most of the snow accumulations should remain
to the north as well.

Wood

&&

.MARINE...
Issued 247 PM CST Sat Dec 20 2025

Low pressure of 29.3 inches will continue across Ontario
tonight. The associated cold front will cross Lake Michigan from
northwest to southeast through early evening. Gusty southwest
winds will veer west-northwest by late evening. Widespread gales
up to 40 kt with a few gusts up to 45 kt are expected during
the evening hours in the wake of the front. Moderate freezing
spray is anticipated as Arctic air settles in, with pockets of
heavy freezing spray possible.

The Gale Warning goes into effect at 3 PM this afternoon for
the nearshore areas of southeast WI. This is a little early, but
the wind gusts will ramp up quickly between now and 6 PM this
evening. Gale gusts may end prior to the 3 AM Sunday end time of
the warning, and it looks like gusts will quickly fall below 25
kt by 6 AM Sunday.

Winds will steadily diminish Sunday, as 30.5 inch high pressure
slides across Illinois and Indiana. Low pressure of 29.8 inches
will develop over the Great Plains on Monday and track across
the Upper Great Lakes Monday night. Southwest winds with 30 knot
gusts are possible during the day Monday, though gale potential
is low at this time. Winds will weaken Tuesday through
Wednesday, as the next area of high pressure of 30.4 inches
crosses the Great Lakes.

Cronce

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Gale Warning...LMZ643-LMZ644-LMZ645-LMZ646 until 3 AM
     Sunday.

     Gale Warning...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-
     LMZ565-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-
     LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 until 3 AM
     Sunday.

&&

$$

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