566
FXUS63 KGRB 130746
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
246 AM CDT Fri Mar 13 2026

Forecast discussion for routine morning forecast issuance

.KEY MESSAGES...

- Ongoing winter system to bring additional snow through the
  morning period, with up to another 4 to 6 inches possible for
  far northeast Wisconsin and northern Door County. Winter Storm
  Warnings and Winter Weather Advisories are in effect.

- Strong winds accompanying the system will increase through the
  morning and last into the afternoon today, with gusts up to 40
  to 50 mph possible (40-60%), which will increase impacts of any
  falling snow and may result in rapid reductions in visibility
  at times due to patchy blowing and drifting snow. Wind
  Advisories are in effect.

- Major winter storm is expected from Saturday night through
  Monday with the potential for significant disruptions and
  impossible travel conditions across the region. Significant snow
  totals are expected, with high probabilities for exceeding 12
  inches of snowfall (70-100%). Some areas may approach or break
  record snowfall. Strong wind gusts are also expected. Those
  with travel plans, including air travel, should monitor the
  weather closely and make alternative plans. A Winter Storm Watch
  has been issued for the entire area.

&&

.DISCUSSION...
Issued at 246 AM CDT Fri Mar 13 2026

Today...

The ongoing clipper system will continue to bring snowfall across
the region through the morning hours before quickly departing in
the afternoon hours. Early morning observations show rain
beginning to mix in across portions of central Wisconsin to east-
central Wisconsin, with snow predominantly only on grassy and
raised surfaces but struggling to get on roads. Therefore, will
leave these areas free of winter weather headlines for now.
Further north, snow has shown better accumulation, especially for
areas north of a line from Wausau to Oconto. Moderate to
occasionally heavy snowfall remains in these areas and is forecast
to continue, adding up to 3 to 5 inches to many areas. The main
change for the winter headlines will be upgrading Door County to a
Winter Storm Warning, primarily for the northern portions of the
County and Washington Island, which will see an increase in
overall snowfall on the backside of the passing clipper as winds
shift to the northeast. Probabilistic guidance suggests a 70-80%
chances of exceeding 5 inches for this northern area, which
combined with the increased winds up to 45 mph during this period,
will likely see heavier impacts, thus the upgrade.

Wind-wise, morning observations show decent mixing with gusts up
to 25 to 40 mph at times across portions of our area. These winds
will shift to the northeast through the morning and likely see
some increases up to 35 to 50 mph at times by the mid to late
morning hours and last into the afternoon (40-60% chance at any
one location). Thus, no changes expected to the Wind Advisory at
this time. Fortunately, the main core of winds aloft, which have
been observed to bring 50 to 60 mph wind gusts to the surface in
Iowa overnight, will likely miss our area to the south, bringing
the stronger gusts to areas of northern Illinois and southern
Wisconsin.

Weekend System...

A major winter storm is expected to impact the region starting
Saturday night and lasting into Monday, bringing widespread travel
disruptions and impacts to most of northeastern Wisconsin. The
long residence time, ample moisture drawn all the way from the
Gulf, and significant dynamic forcing will all serve to bring some
impressive, possibly even record setting snowfall to the region.
Probabilistic guidance remains near 70-100 percent for over a
foot of snowfall, with a corridor of 40-70% for two feet of
snowfall over the course of the 36 to 48 hours. This would also
make for some locally even higher amounts in the areas of the
strongest snowbands. The main uncertainty that has crept into this
forecast will be along the southern edge of the snowband where
soundings suggest the warmth and moisture aloft may be sufficient
for sleet and possibly some freezing rain. This would reduce snow
totals for portions of the Fox Valley and eastwards to the
lakeshore areas in east- central Wisconsin, but areas further
north and west will still see higher amounts. It also bears
mentioning that even "reduced snowfall" for this system is still
around or over a foot of snow; all things are relative.
Accompanying the snowfall will be a period of strong wind gusts,
with guidance suggesting widespread 80%+ of exceeding 35 mph gusts
at times. Combining these factors increases the potential for
blizzard and possibly whiteout conditions at times Sunday through
Monday, which will bring widespread travel disruptions. The main
question that remains is where these conditions will align best,
given the aforementioned changes on the southern end. All said,
expect travel to become extremely difficult to impossible Sunday
into Monday, so now is the time to make alternate arrangements.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1053 PM CDT Thu Mar 12 2026

Poor flying conditions will continue into much of Friday as a
strong clipper system moves across the Great Lakes. Look for
IFR/LIFR ceilings and visibilities, with brief periods of VLIFR
possible in the heaviest snow. Snow rates will be fairly high in
the main snow band, up to 2" per hour, which may impact ground
operations. The snow could change back to rain overnight, mainly
south of Hwy 29 overnight as the heaviest band shifts east. The
main area of snow will exit by around 12z Friday, with light snow
continuing over northern WI, with snow showers possible at times
elsewhere on Friday. Added some TEMPO groups for some heavier snow
showers over east-central WI in the late morning and early
afternoon. Conditions start to improve later Friday afternoon and
evening.

Strong winds will accompany this system, with gusts up to 30 to
40 kts expected to reach the surface at times overnight into
Friday morning, locally to 45 kts. The highest wind gusts are
expected across the east-central WI TAF sites late this evening,
and across the central and east-central WI TAF sites Friday
morning. Southeast winds are expected at the start of the TAF
period, turning west/northwest Friday morning. Additionally,
strong winds aloft will create a period of LLWS at all TAF sites
mainly between 06z-12z Fri.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning until 1 PM CDT this afternoon for WIZ005-
010>013-018>021-073.

Winter Storm Watch from Saturday evening through Monday
afternoon for WIZ005-010>013-018>022-030-031-035>040-045-048>050-
073-074.

Winter Storm Warning until 1 PM CDT this afternoon for WIZ022.

Winter Weather Advisory until 1 PM CDT this afternoon for WIZ030-
031-074.

Wind Advisory until 6 PM CDT this evening for WIZ035>040-045-
048>050.
&&

$$

DISCUSSION.....Uhlmann
AVIATION.......Bersch

NWS GRB Office Area Forecast Discussion