819
FXUS63 KMKX 170316
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
916 PM CST Tue Dec 16 2025

.KEY MESSAGES...

- Milder temperatures expected through early Thursday, with
  highs in the middle to upper 30s.

- 65-90% rain chances are forecast from late Wednesday night
  through Thursday morning. There are 20-40% chances for light
  precipitation to continue Thursday afternoon and evening, with
  a gradual transition to light snow.

- Significantly colder temperatures (single digit low temps)
  expected Thursday night, freezing any surfaces that remain wet
  from Thursday`s rain and snow.

&&

.UPDATE...
Issued 915 PM CST Tue Dec 16 2025

Forecast remains largely on track this evening. Broken mid-
upper clouds have filled in across the region ahead of a
disturbance approaching from the Northern Plains, leading to
nearly steady temperatures. A surface front accompanies the
aforementioned disturbance, with 9 PM CST surface obs placing
the boundary along an approximate Bayfield, WI to Rochester, MN
axis. Moving in tandem with the parent upper disturbance, the
front will quickly progress east across the region through the
predawn hours, resulting in a gusty northwest wind shift. Dry
conditions in the lower part of the column will keep conditions
precip-free during the frontal passage. The post-frontal
northwest winds will bring a slightly cooler air mass into the
region for the day tomorrow.

Quigley

&&

.SHORT TERM...
Issued 338 PM CST Tue Dec 16 2025

Tonight through Wednesday night:

A surface trough/cold front will slide across southern WI
tonight. This is coincident with a mid level trough. South-
southwest winds are gusty ahead of it and northwest winds will
continue to be a little gusty behind it during the overnight
hours. Our temperatures over-performed this afternoon with the
extreme warm air advection. Expect mid level clouds along the
front this evening. There is a chance for some scattered low
clouds behind it during the overnight hours due to trapped low
level moisture, but the air (and winds) just above the inversion
will be very dry (and gusty). The question is how much mixing
will occur down to the surface behind the front. The hinting of
low clouds from the models and trapped low level moisture may
also be from the melting snow with the mild temps this
afternoon. The winds should be high enough to prevent fog, but
the stratus would be the result instead.

Wednesday, the surface high will slide across IL, so winds over
southern WI will actually be light and generally out of the
west. If clouds stall over the IL/WI border along the weakening
front Wed morning, this will slow down our cooling tonight but
also the warming on Wednesday. However, low pressure
approaching from the Northern Plains will bring us right back
into a warming pattern by Wed afternoon. With sunshine and
increasing southerly winds, we should be able to get back into
at least the mid 30s, but given how this afternoon over-
performed, I would not be surprised to see 40 along the IL
border. Fog is possible Wednesday night.

Cronce

&&

.LONG TERM...
Issued 338 PM CST Tue Dec 16 2025

Thursday through Tuesday:

Low level moisture will surge into southern WI early Thursday
morning. Rain or drizzle is possible initially (30 to 50%
chance), and then deeper moisture will arrive shortly after
12Z/6AM as the surface low of this occluding system tracks into
northeast MN. The initial surface trough/cold front will slide
through southern WI during the daylight hours, and the secondary
cold front (925-850mb cold front) will cross during the late
afternoon/evening hours. This secondary front will feature gusty
west to northwest winds and a sudden drop in temperatures. Thu
nt lows will drop into the single digits to lower teens, with
min apparent temps in the negative single digits.

A high pressure ridge will return Friday afternoon with lighter
winds and highs in the lower to mid 20s. The next clipper will
cross Ontario near Lake Superior Saturday. Southern WI will be
above freezing in most of southern WI during the day, with the
precip chances mainly over northern WI. One more weaker clipper
will take the same track Sunday evening and should not impact
us.

Monday afternoon and evening could bring a wintry mix to
southern WI with a period of warm air advection as the next
clipper approaches. This could lay out a stalled frontal
boundary over southern WI on Tuesday, so a period of light rain
or at least low clouds is possible.

Cronce

&&

.AVIATION...
Issued 915 PM CST Tue Dec 16 2025

VFR flight categories prevail through the period at most
terminals. Gusty winds will continue through the overnight
period as a cold front crosses southern Wisconsin. The passing
boundary will result in a northwest wind shift at all terminals
by the predawn hours. LLWS potential will continue along/behind
the departing front into early Wednesday morning. Frontal
passage will also be accompanied by FEW-SCT clouds near FL020.
Don`t currently expect clouds to be thick enough for categorical
reductions, though trends will need to be monitored through
daybreak, particularly in east-central Wisconsin. Should low
clouds trend thicker, MVFR mentions may become necessary. Winds
will taper late Wednesday morning as high pressure moves into
the region, ending LLWS potential at all terminals. An upper
disturbance will move into the Upper Mississippi Valley
Wednesday night, bringing precip chances to all of southern
Wisconsin. Will need to account for precip potential in
subsequent updates at all aerodromes.

Quigley

&&

.MARINE...
Issued 338 PM CST Tue Dec 16 2025

High pressure will linger across the Southeast U.S. through
Wednesday. Meanwhile, low pressure currently over southwestern
Ontario will lift into western Quebec tonight, leading to
continued gales across the northern two-thirds of the open
waters through early Wednesday morning. A Gale Warning is in
effect. Winds will veer westerly then northwesterly and diminish
into early Wednesday morning behind a cold front. Light winds
then are expected through Wednesday afternoon. The Small Craft
Advisory is in effect through late tonight.

Low pressure then tracks eastward along the Canadian border
Wednesday night into Thursday, bringing southerly gales once
again late Wednesday night into Thursday morning. A brief period
of lighter winds is expected Thursday morning into Thursday
afternoon as low pressure crosses the Upper Peninsula of
Michigan. Winds turn westerly, then northwesterly Thursday
evening, with gales returning to the southern half of the open
waters early Thursday evening. Northwesterly gales will return
to the northern half late Thursday night. Gale Watches are in
effect for each area for these time frames. Winds will diminish
below gale force Friday morning and become light and variable.

Friday night, another low pressure system swings through southern
Canada, bringing gusty south-southwest winds once again. Gales are
possible, but confidence is lower with timing and intensity at
this time.

Cronce/MH

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Gale Warning...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565-
     LMZ567-LMZ669-LMZ671-LMZ673-LMZ868-LMZ870-LMZ872-LMZ874
     until 3 AM Wednesday.

     Gale Watch...LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565...11 PM
     Wednesday to 10 AM Thursday.

     Gale Watch...LMZ080-LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-
     LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...11 PM
     Wednesday to 9 AM Friday.

     Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646 until 6 AM
     Wednesday.

&&

$$

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