541
FXUS63 KMKX 100329
AFDMKX

Area Forecast Discussion
National Weather Service Milwaukee/Sullivan WI
929 PM CST Tue Dec 9 2025

.KEY MESSAGES...

- A Winter Weather Advisory is in effect for portions of
  southern Wisconsin for snow accumulations as well as the
  potential for some freezing rain and icing due to cold
  pavement temperatures. Travel impacts may occur this evening
  and during the Wednesday AM commute, hence the Advisory has
  been extended in time to encompass the commute.

- Additional rounds of light snowfall are then possible at times
  later Thursday through the weekend.

- Below normal temperatures continue through next weekend, with
  wind chills as cold as -15 to -25 degrees Friday and Saturday
  night.

&&

.UPDATE...
Issued 925 PM CST Tue Dec 9 2025

Milwaukee and Waukesha counties have been added to the existing
Winter Weather Advisory on account of some solid snowfall rates
observed over the past hour or two. The advisory (for all areas)
has been extended slightly in time to encompass the Wednesday
AM commute, given that some lighter snow, falling temperatures,
and gusty winds may continue to pose travel impacts. The
advisory ends 7 AM Wed (West) and 9 AM Wed (East) to reflect the
west to east shutoff of light snow.

Gusty north winds will arrive late tonight into Wednesday
morning, and may make the AM commute even more difficult for
high profile vehicles, especially when operating on east-west
highways like I-94.

We are continuing to monitor the progression of the rain/snow
line northward, and some recent observations suggest that it is
finally beginning to make some northward progress. Stay tuned
for further updates!

Sheppard

&&

.SHORT TERM...
Issued 245 PM CST Tue Dec 9 2025

Tonight through Wednesday night:

A clipper system is anticpated to impact southern Wisconsin this
evening into Wednesday morning. Strong 850-700mb warm advection
and frontogenesis will drive a band of higher qpf ranging from
0.25 to 0.5 inches in a stripe from northwest to southeast
Wisconsin. A better overlap of this qpf and colder temperatures
will exist generally north of I-94 in our area, while areas
south and west will suffer from some mixed precipitation/rain as
sfc warm advection drives temperatures above freezing for a
time overnight.

Light snow/mix may start first in southwest Wisconsin around 4pm
this afternoon. A bit of freezing rain can`t be ruled out as
well, given a very slight on and off warm nose signal from the
CAMs over southwest Wisconsin. Any liquid preciptation that
falls will encounter some below freezing road temps, which may
cause icing.

Otherwise, conditions are expected to deteriorate
pretty quickly north of I-94 tonight as snow will rapidly onset
between 5 to 6pm and rates will quickly increase as the core of
the 850mb fgen moves over central WI ahead of the surface low.
The best rates of 0.5 to 1 inches per hour are expected to move
over central/east- central WI between 9 and 11pm, leading to a
quick 2 to 3 inches of accumulation over Marquette, Green Lake,
Fond du Lac, and western Sheboygan Counties. Rates should then
begin to taper off after midnight, but snow will continue until
shortly after 6am Wednesday, accounting for the rest of the snow
totals north of I-94

Areas along and south of I-94 may see a brief change over to
all rain after the initial light snow/mix/freezing rain 9pm
through midnight as the surface low moves over the area, before
a dry slot impacts the southern 2 tiers of counties over
southern WI. Light snow will then slowly sink south after
midnight and swing southeast through this area before exiting
southeast over Lake Michigan and IL, through 8am.

CAA will then kick in on Wednesday behind the departing surface
low with temps remaining steady in the mid to upper 20s to
slowly falling through the day. Gusty northwest winds will
make things feel chilly outside, with wind chills in the
negative single digits Wednesday night amid air temperatures in
the single digits.

CMiller

&&

.LONG TERM...
Issued 243 PM CST Tue Dec 9 2025

Thursday through Tuesday:

Active northwest flow continues through the end of the week. Our
next chance for snow will arrive later Thursday into Thursday
night, as a band of warm advection and fgen sets up across Iowa,
southwestern Wisconsin, and northern Illinois. There continues to
be some disagreement with the exact placement of this band, but at
this time it seems probable that the majority of the accumulating
snow will be south and west of Madison (and perhaps largely to the
southwest of our CWA), with much lighter amounts to the north and
east. Highs Thursday will be rather chilly, with readings in the
teens and 20s, and overnight lows Thursday night into Friday
morning in the single digits and low teens.

Some additional light snow will be possible with a cold front
Friday, followed by another swipe of snow (mainly) to the
southwest on Saturday. That front will usher in a very cold
airmass, with highs on Saturday and Sunday expected to be in the
single digits, with lows between zero and 10 below. Wind chills
Saturday and Sunday morning will approach Advisory levels.

Some moderation in temperatures is expected early next week,
though with considerable uncertainty as to what degree.

Boxell

&&

.AVIATION...
Issued 810 PM CST Tue Dec 9 2025

Moderate precipitation rates continue for the next several
hours, with the rain/snow line (currently just south of the I-94
corridor) beginning to slowly shift northward thru midnight CST
tonight before stalling. In this time window, the existing low
cloud ceilings (already at predominantly IFR levels) will
worsen, and a brief window of low-level wind shear will occur
for southern and southwestern Wisconsin due to a low-level jet
streak (this includes the KMSN, KJVL, and KENW TAF sites). The
rain/snow line should progress to a KDLL/KUNU/KETB/KSBM line
before stalling.

From 2 AM CST Wednesday onwards, precipitation rates should
decrease to light (half inch or less snow per hour), but the
rain/snow line will then progress southward, passing the WI/IL
border and leaving the whole region with all-snow by roughly 6
AM CST Wednesday morning. From 6 to 10 AM CST Wednesday, a
sharp cutoff in the light snow should then occur from NW to SE
across the region, along with gusty north winds. Mostly dry
conditions and slightly improved (MVFR) cloud ceilings expected
mid Wednesday, with 30kt north to northwest wind gusts beginning
to slowly back off. There are some slight chances for flurries /
light snow showers mid to late Wednesday afternoon, but
confidence is too low for inclusion in TAFs at this time.

Sheppard

&&

.MARINE...
Issued 244 PM CST Tue Dec 9 2025

Low pressure will track from Minnesota across southern Lake
Michigan and into Lower Michigan tonight. Southwest to westerly
gales will develop ahead of the low over the southern third of
the lake tonight, followed by northwest to northerly gales
expanding across the southern two thirds of the lake as the low
passes early Wednesday morning. The brisk winds will then
gradually diminish Wednesday night. A period of northwesterly
gales may then return Friday night into Saturday as a strong
arctic front moves through the Great Lakes region. Heavy
freezing spray may also develop.

Boxell

&&

.MKX WATCHES/WARNINGS/ADVISORIES...
WI...Winter Weather Advisory...WIZ046-WIZ047-WIZ051-WIZ056-WIZ057-
     WIZ058-WIZ062-WIZ063-WIZ064-WIZ067-WIZ068-WIZ069 until 7
     AM Wednesday.

     Winter Weather Advisory...WIZ052-WIZ059-WIZ060-WIZ065-WIZ066
     until 7 AM Wednesday.

LM...Gale Warning...LMZ080-LMZ673-LMZ675-LMZ777-LMZ779-LMZ874-
     LMZ876-LMZ878 until 6 PM Wednesday.

     Gale Warning...LMZ366-LMZ565-LMZ567-LMZ669-LMZ671-LMZ868-
     LMZ870-LMZ872...5 AM Wednesday to 6 PM Wednesday.

     Gale Warning...LMZ643-LMZ644-LMZ645-LMZ646...5 AM Wednesday to
     noon Wednesday.

     Small Craft Advisory...LMZ643-LMZ644-LMZ645-LMZ646 until 5 AM
     Wednesday.

&&

$$

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