575
FXUS63 KMKX 171012
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
412 AM CST Wed Dec 17 2025

.KEY MESSAGES...

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

- A widespread light rainfall event is expected 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 (overnight lows in the
  single digits to low teens) expected Thursday night, freezing
  any surfaces that remain wet from Thursday`s rain and snow.

&&

.SHORT TERM...
Issued 400 AM CST Wed Dec 17 2025

Today through Thursday night:

Dry and mild weather expected to continue through this evening
in advance of the next low pressure system, which will track
along the USA/Canada borderline today through Tonight, crossing
the Upper Peninsula of Michigan Thursday afternoon before
lifting northeastward. A widespread light rainfall event is
expected late Wednesday night through Thursday morning, driven
by strong WAA in advance of the low pressure system as well as
an occluded frontal boundary extending south of the low (which
crosses our region between 6 AM and Noon CST Thursday). Rain
totals around two to three tenths of an inch are generally
expected across the region, with locally higher totals to 3
quarters of an inch possible. The majority of this will fall
with the passage of the occluded front.

Breezy west winds, falling temperatures (surface and aloft), and
a lull in the precipitation are looking likely at some point
early Thursday afternoon as a dry slot wraps into the low
pressure system and overspreads our area. 20-40% chances for
light precip are then forecast later Thursday afternoon into
Thursday evening as a secondary frontal boundary (a true cold
front this time) crosses our region. This precip would feature a
rapid transition to snow, though accumulations would be minimal
(judging by the minimal QPF afforded by models this late in the
event and drier air wrapping into the low pressure). That being
said, pavement left wet by the rain/snowfall on Thursday would
then freeze solid Thursday evening / night as temperatures fall
well below freezing. Thursday night lows in the single digits to
low teens are forecast across the region. Winds behind the
occluded front and cold front also have the potential to be
quite gusty, we`re currently calling for 30 to 35 MPH wind
gusts but a slight increase to these estimates may be needed if
trends warrant.

Sheppard

&&

.LONG TERM...
Issued 400 AM CST Wed Dec 17 2025

Friday through Tuesday:

GEFS and ECMWF Ens show fairly good agreement during this period.
Nwly winds and cold advection will cease Fri AM as low pressure
moves away across srn Ontario and Quebec. A surface ridge passage
will then follow for the afternoon with temperatures remaining
cold due to the polar airmass.

Sly winds and warm advection will then begin Fri nt as low
pressure in the 990s millibars tracks from srn Manitoba into
Ontario. The low to mid level warm advection will bring 20
percent chances for light snow over portions of east central WI.
The associated upper wave and sfc low will then move across
Ontario and the Lake Superior region on Sat. The warm advection
will continue into Sat AM and bring 20 percent chances for light
snow east and north of Madison, including the MKE metro. Sly
winds will shift wly with an initial cold front, but the stronger
polar cold front will arrive Sat nt. Temperatures will warm into
the 30s on Sat then dropping into the single digits north and west
of the MKE metro area by 12Z Sun. Polar high pressure will then
pass Sun afternoon and evening with cold temperatures continuing.

Another period of sly winds and warm advection will then ensue
late Sun nt and Mon as low pressure develops in the nrn high
plains. This low will evolve to a weaker low across the Lake
Superior region and Ontario late Mon nt-Tue with a weak cold
frontal passage for srn WI on Tue. High temps will warm through
the 30s from Mon into Tue.

Gehring

&&

.AVIATION...
Issued 400 AM CST Wed Dec 17 2025

An arc of 2,000 to 3,000 ft AGL clouds over northern WI is
gradually approaching our region, but appears to be scattering
out as it arrives this morning. A brief period of MVFR from
these clouds cannot be ruled out, but the most likely solution
is continued VFR through this morning with decreasing northwest
winds. Low level wind shear will continue to pose a threat until
around 7 AM this morning, with 2,000 ft winds out of the
northwest around 35 to 40 knots. Dry weather and VFR continue
through the afternoon.

Accelerating south winds and increasing cloud cover expected
this evening, with 20 to 30 knot gusts and decreasing ceilings
late (likely IFR or LIFR by Thursday morning). Light to
moderate rain builds into the region from the west between
Midnight tonight and 6 AM CST Thursday, peaking in the morning
then tapering off west to east towards Noon. Afterwards,
similarly gusty (or possibly stronger) west winds build into
the region, with temperatures rapidly falling below freezing.
There are some 20-40% chances for lingering precipitation
Thursday afternoon and evening, which would be in the form of
light snow showers. Cloud ceilings may rebound briefly to MVFR
Thursday afternoon (possibly even VFR in the event of a dry slot
wrapping into the low pressure system), but may fall back to
pockets of MVFR / Fuel Alt MVFR as the light snow showers move
in. Said snow showers may cause brief reductions in visibility
as well, with wet pavement (due to the prior rainfall) and
plummeting temperatures also presenting some concerns.

Sheppard

&&

.MARINE...
Issued 400 AM CST Wed Dec 17 2025

Breezy west to northwest winds will subside through this
morning, with light and variable winds this afternoon and
building south winds after dark this evening.

Low pressure around 29.1 inches will track eastward along the
Canadian border Wednesday night into Thursday, bringing southerly
gales Wednesday night into Thursday morning. A lull in the gales
may occur later Thursday morning into Thursday afternoon as low
pressure crosses the Upper Peninsula of Michigan, though it should
still be gusty. Winds turn west and accelerate back to gale force
behind the cold front Thursday afternoon/evening, then eventually
northwest Thursday night. A Gale Warning is in effect for all
open waters of Lake Michigan late this evening through Friday
morning.

Moderate freezing spray is expected to accompany the gales late
Thursday night into Friday morning as a bitter cold airmass
briefly enters our region.

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.

Sheppard

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...None.
LM...Gale Warning...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-
     LMZ565-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.

     Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646...6 PM
     Wednesday to 6 PM Thursday.

     Gale Watch...LMZ643-LMZ644-LMZ645-LMZ646...6 PM Thursday to 6
     AM Friday.

&&

$$

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