NWS-Green Bay Forecast Discussion

						FXUS63 KGRB 151135
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
635 AM CDT Sun Mar 15 2026

Updated aviation portion for 12Z TAF issuance

.KEY MESSAGES...

- A historic winter storm will impact the region through Monday.
  Heavy snow, mixed precip, and strong winds will create blizzard
  conditions as well as widespread and significant impacts across
  the area, including extremely difficult to impossible travel and
  power outages. Winter Storm Warnings and Blizzard Warnings have
  been issued.

- Sleet and/or freezing rain will likely mix with snow at times
  across east-central Wisconsin, resulting in the potential for
  0.1 to 0.2" of ice accumulation through this afternoon. Precip
  then transitions back to all snow tonight.

- Below zero wind chills will be possible on Monday, moderating
  back to near normal throughout the week.

&&

.DISCUSSION...
Issued at 123 AM CDT Sun Mar 15 2026

Historic winter storm continues... Light to moderate snow
continued to spread northeast overnight in conjunction with a push
of WAA and resultant FGEN. The snow will continue to increase in
intensity throughout the morning as higher snowfall rates (2 to
3"/hr at times) arrive in tandem with greater forcing from a
potent mid-level trough and influx of Gulf moisture. Most models
still develop an elevated warm layer starting at around 5k ft
across our southern tiers of counties later this morning,
bringing with it the potential for either sleet or freezing rain
to mix with snow at times across east-central Wisconsin. Any mixed
precip would cut slightly into snowfall totals across the Fox
Valley and lakeshore areas, though confidence remains high (50 to
80% chance) for receiving at least 18 inches of snow. Total ice
accumulations (on top of the snow that has already fallen) will be
around 0.1 to 0.2 inches, mainly along an axis from Waushara to
Manitowoc counties. There remains uncertainty regarding exactly
how far north and how aggressive the warm nose will be, which,
worse case scenario, would mean dramatically increasing snowfall
amounts across the Fox Valley were it not to materialize. As it
stands now, we should start to see mixed p-types appearing within
the next few hours.

Heavy snow will continue north of Hwy 29 throughout the day as the
main deformation precip shield makes it way over the northern
half of the state. Winds increase out of the northeast later this
morning, gusting between 40 and 50 mph, locally higher, this
afternoon as the pressure gradient tightens up following cold
FROPA. When combined with high snowfall rates, blizzard conditions
are expected to develop from northwest to southeast this
afternoon, lasting into Monday afternoon. A return to all snow
then occurs over east-central Wisconsin late this evening as
colder air wraps in around the back end of the departing low.
Probabilities for receiving 2 ft of snow remain at an astonishing
70 to 100% across the Northwoods, with a 60 to 90% signal for 30
inches of snow. While 30+ inch totals are well within the realm of
possibility, it should be noted that the effects of compacting
may not result in 30 inches of snow on the ground. Snow then
gradually tapers off Monday afternoon.

Headlines... No outstanding changes to the winter weather
headlines were made on this shift. There remains high confidence
that blizzard conditions will be met across most of the forecast
area, though the onset time could vary by plus or minus an hour or
two across the northwestern cut where winds are slightly slower
to mix down.

Extended... Northwesterly flow regime will result in a period of
below normal temperatures early next week, including below zero
wind chills on Monday. Highs then slowly moderate back to near
normal, and even above normal, throughout the work week.
Otherwise, transient shortwave energy dives over the Great Lakes
mid-week, resulting in the possibility of picking up another
inch or two of snow. No significant impacts are currently
expected. Beyond that, 500 mb pattern starts to de-amplify later
in the week as weak ridging establishes itself over the CONUS.

&&

.AVIATION...for 12Z TAF Issuance
Issued at 619 AM CDT Sun Mar 15 2026

Moderate to heavy snow and IFR to LIFR cigs persist over the
forecast area as of this morning. Snow will continue to intensify
throughout the day, with rates reaching 1 to 2 inches per hour at
times. Sleet and freezing rain have begun to mix with the snow
across the east-central sites and will continue to do so at times
throughout the day, before transitioning back to all snow by
tonight. 0.1 to 0.2 inches of ice accumulation will be possible
mainly at ATW and MTW, though up to 0.1" will be possible at GRB.
Expect flight delays and/or cancellations through at least Monday
morning, with airport closures also possible.

Winds continue to increase out of the northeast into this
afternoon, gusting between 30 and 40 knots at all terminals. When
combined with heavy snow, blizzard conditions are expected to
develop from northwest to southeast this afternoon, resulting in
prolonged periods of quarter mile or less vsbys into Monday
afternoon. LLWS continues throughout the TAF period as 850 mb
winds crank up to near 60 knots.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning until 10 AM CDT this morning for WIZ005-
010>013-018>022-030-031-035>037-045-073-074.

Blizzard Warning from 10 AM this morning to 4 PM CDT Monday for
WIZ005-010>013-018>022-030-031-035>037-045-073-074.

Winter Storm Warning until 4 PM CDT this afternoon for WIZ038-
039-048-049.

Blizzard Warning from 4 PM this afternoon to 4 PM CDT Monday for
WIZ038-039-048-049.

Winter Storm Warning until 7 PM CDT this evening for WIZ040-050.

Blizzard Warning from 7 PM this evening to 4 PM CDT Monday for
WIZ040-050.
&&

$$

DISCUSSION.....Goodin
AVIATION.......Goodin