NWS-Green Bay Forecast Discussion
FXUS63 KGRB 131940
AFDGRB
Area Forecast Discussion
National Weather Service Green Bay WI
240 PM CDT Fri Mar 13 2026
.KEY MESSAGES...
- A major winter storm will impact the region late Saturday
through Monday with widespread snow/ice with significant
travel impacts. Winds gusting 35 to 45 mph could lead to
blizzard or near blizzard conditions late Sunday into Monday
with power outages and some tree damage.
- Although widespread impacts are expected across the region,
recent trends have supported a slightly farther north
placement of the highest snow amounts, with increasing
potential for some mixed precipitation in parts of the Fox
Valley on Saturday night into Sunday. The exact track will
impact where highest snow amounts occur.
- Colder conditions early in the week (wind chills below zero
at times) will gradually moderate through the week.
&&
.DISCUSSION...
Issued at 240 PM CDT Fri Mar 13 2026
This afternoon-Tonight:
A strong surface low across northern Lake Michigan continues to pass
eastward this afternoon with some lingering light snow over
north-central WI. Low- level cold advection and strong 850 mb
wind core has resulted in gusty northwest winds, in excess of 45
mph gusts across parts of central into east-central WI. Winds
will gradually diminish through the evening.
Saturday-Monday: Major, Potentially Record-setting Winter Storm
Confidence remains high for a major, long duration winter storm to
impact the region late Saturday, persisting through Monday.
Synoptically, a trough mid-level trough will roll eastward across
the Midwest with a surface low lifting across the western Great
Lakes on Monday with a tight pressure gradient setting up
between the low and a 1030 mb high nosing into the plains.
This will be a long duration event with initial warm advection
precip developing on Saturday night into Sunday before the
deformation zone precip shield wraps across the area Sunday night
into Monday. Ultimately, given the long-duration event and
likelihood for 1 to 3 inch snow rates at times within the
heaviest snow, a band of high end record type snowfall remains
on the table. However, of note from recent model trends has
been a northward nudge of solutions with the low track, with
some ensemble members taking a track as far north as southern
Wisconsin. The effect of a more northern track would be for
increased rain/sleet/freezing rain potential across central
Wisconsin Saturday night into Sunday before colder air wraps in
behind the low. This also nudges the favored area for highest
into northern Wisconsin. Thus, confidence in snow amounts is
lowest in this transition area, pending the ultimate track of
the low.
However, all areas will transition back to snow by Sunday evening
into Monday as the low pulls east and colder air wraps in. Winds
will increase through the day Sunday, with gusts of 40+ mph likely
at times Sunday afternoon through Monday. As colder air moves in,
the wetter snow character will trend drier. The combination of
strong, gusty winds with the falling snow may lead to whiteout
conditions and potential blizzard conditions especially late
Sunday into Monday.
Probabilities remain quite high for a band of over 12 inches (60-
90%), right now highest across northern Wisconsin with even 60-80%
probabilities for over 18 inches across northern Wisconsin. The
intense rates at times will cause widespread travel impacts,
while snow load will likely result in some power outages/downed
tree limbs, in concert with the strong winds. Again, though,
small shifts in track will impact where band of highest amounts
occur.
For now, upgraded the Winter Storm Watch to a Winter Storm Warning
area-wide beginning Saturday night. Some adjustments likely will be
needed through the weekend, with a consideration that upgrades to
Blizzard Warnings could be needed for at least parts of the area as
winds begin to ramp up. It's important to note that this winter
storm will bring widespread impacts over a longer duration, with
variable impacts throughout the period. Even areas that may receive
mixed precipitation or possibly some rain will transition back to
snow. These details will be refined through the start of the
weekend.
Tuesday-Friday:
Broad northwesterly flow will be in place through the remainder of
week with a trend towards moderating temperatures. However, Monday
night lows in the single digits combined with gusty winds may yield
wind chills as low as 10 to 20 below zero. The moderating trend may
be slowed a bit by the snow cover that likely will be in place.
A progressive shortwave trough may bring some light snow for mid-
week (40-60%), but overall impacts appear minor.
&&
.AVIATION /18Z TAFS THROUGH 18Z SATURDAY/...
Issued at 1224 PM CDT Fri Mar 13 2026
Areas of MVFR CIGS or VSBYs continue through mid afternoon due to
scattered rain/snow showers moving across the area. The precip
should end by late afternoon across the entire area with CIGS
moving into the VFR category later this afternoon and evening.
Attention then turns to the next significant impactful winter
storm Saturday night through Monday. Heavy snow, strong winds,
amd possibly a wintry mix Sunday across east-central WI before
transitioning back to snow Sunday night. Over a foot of snow
is likely, with a few spots receiving over 2 feet are possible.
A light glaze of icing is possible across east-central WI,
including the Fox Valley and lakeshore region late Saturday
night and Sunday. Strong wind gusts over 35 knots are likely
Sunday night and Monday, with gusts up to 45 knots possible.
&&
.GRB WATCHES/WARNINGS/ADVISORIES...
WI...Winter Storm Warning from 1 AM Sunday to 4 PM CDT Monday for
WIZ005-010>013-021-073.
Winter Storm Warning from 7 PM Saturday to 4 PM CDT Monday for
WIZ018>020-022-030-031-035>040-045-048>050-074.
Wind Advisory until 6 PM CDT this evening for WIZ035>040-045-
048>050.
MARINE...Gale Warning until 7 PM CDT this evening for LMZ541>543.
Small Craft Advisory from 7 PM this evening to midnight CDT
tonight for LMZ541>543.
&&
$$
DISCUSSION...JM
AVIATION...Eckberg