NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 131119
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
519 AM CST Tue Jan 13 2026

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- A light mix of rain, freezing rain, sleet and snow will result
  in hazardous travel across north central and northeast Wisconsin
  this morning. Icy conditions will impact the morning commute in
  the Northwoods.

- Accumulating lake-effect snow may cause additional travel
  concerns in far north central Wisconsin tonight into Wednesday.

- Widespread snow late Thursday afternoon through Friday, with
  additional chances for light snow through the weekend.

- Still mild today, then turning colder Wednesday through the
  weekend.

&&

.DISCUSSION...
Issued at 223 AM CST Tue Jan 13 2026

Active pattern continues through the week. Mixed precip to start,
then only snow as cold settles across the region. No heavy snow is
anticipated through the coming weekend, but a couple times of
widespread fresh light accumulations are likely, especially Thursday
afternoon through Friday.

Strong clipper low with MSLP of 989mb is over central Canada this
morning, just entering northwest Ontario. Strong warm air advection
over upper Mississippi river valley has been tempered by dry air
as seen on 00z MPX sounding. Result has been precip struggling to
build south over MN this morning, with only a few obs of light
rain and/or UP noted. Trends of models picking up on this,
showing main push of light precip eventually impacting areas
mainly north of highway 29. Ptype is a mess with initial warm air
advection giving way to wet-bulb cooling. Result is rain/freezing
rain (depending on sfc temps)/sleet mixing with snow eventually
if stronger saturation occurs. Not completely sold that will be
the case based on upstream trends, but models do point to better
coverage of precip toward 12z/6am and are beginning to see more
obs with precip upstream. Wondering though when precip makes it to
the 29 corridor if temps may be a bit too warm for any freezing
precip as readings are steadily coming up slightly above freezing
in the last couple hours. Overall, will keep the Winter Weather
Advisory as is and not expand it any farther south. Main icing up
to a few hundredths will be through mid morning over northern WI.
Then as colder air starts to arrive aloft, may see another round
of scattered rain/snow showers this afternoon north-central to
central WI.

Sharp trough axis aloft drops in overnight tonight dragging coldest
air aloft (850mb temps -18c to -20c) over WI. Retained the widespread
pops overnight into Wednesday morning for light snow. As the cold
air arrives behinds sharp sfc cold front, it will become blustery
and noticeably colder at the sfc, with readings by daybreak on
Wednesday around 10 above north, to near 20 Fox Valley to lakeshore.
Apparent temps will be below zero north and in the single digits
above elsewhere. It will feel like quite the change compared to
the recent mild weather. Lake effect expected into north-central
WI on Wednesday, with a few flurries at times elsewhere. Given the
dry airmass, clouds will begin to break up through the day in
downslope areas of central and eastern WI. Even with some sun,
temps and apparent temps will stay steady.

We'll see brief ridging and warm air advection aloft late Wednesday
night into Thursday. Stronger shortwave trough arrives by Thursday
night, spreading light snow across the entire western Great Lakes
region into Friday. Probabilities for an inch of snow are higher
with the system (60+%), but chances for 2" are only 20-50% and
chances for 4" are 5-15%. Temps on Friday bounce back (mid
20s-lower 30s) as the system moves through, but become cold again
for the weekend. Highs will be in the teens and lows will be below
zero for parts of the area. Apparent temps could drop toward 20
below both Saturday night into Sun AM and again Sunday night into
Mon AM.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 518 AM CST Tue Jan 13 2026

Patchy wintry mix shifts through the area this morning, with
greatest risk for any icing over far northern WI. Carried mention
of light rain at all terminals, but did include rain/snow mention
at RHI. VFR conditions to start the day, but expect cigs to lower
to MVFR at times for the region later this morning through the
rest of the TAF period. Cold front moves through tonight from the
north. Expect a burst of snow along the front over northern WI, so
have placed a TEMPO for IFR vsby in at RHI. Elsewhere, expect
patchy scattered light snow (prevailing VFR vsby) through the
night.

Winds start the day from light southwest, but shift west and
increase mid to late morning. Gusts to around 25 kts this
afternoon. Winds veer more northwest-north this evening and
overnight in wake of the strong cold front. Gusts up to 25 kts
will remain possible through the night. LLWS of 40-45 kts over
central WI at beginning of TAF period will spread to eastern WI
through early this afternoon, before ending by this evening.

&&

.MARINE...
Issued at 223 AM CST Tue Jan 13 2026

Westerly winds reach Small Craft Advisory criteria today as
strong low tracks north of Lake Superior. Strong cold front tied
to the low moves through tonight. Stronger northwest winds, with
frequent gale gusts to 40 kts, are expected late tonight through
Wednesday evening. The strongest winds will be over the Lake
Michigan waters. Even with an offshore northwest wind direction,
waves will be higher and there will be moderate to at times heavy
freezing spray.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 9 AM CST this morning for WIZ005-
010>013-018-019-021-073.
&&

$$

DISCUSSION.....JLA
AVIATION.......JLA
MARINE.........JLA