204
FXUS63 KGRB 300500
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1100 PM CST Sat Nov 29 2025

Updated aviation portion for 06Z TAF issuance

.UPDATE...
Issued at 738 PM CST Sat Nov 29 2025

Light to occasionally moderate snows continue across all of the
forecast area early this evening. Radar showed fairly impressive
returns across the southeast half of the forecast area (including
the Fox Valley and lakeshore areas), in response to strong
forcing with a negatively-tilted short-wave trough.

Snow accumulations thus far have been underwhelming, seemingly due
to lower snowfall to water ratios than previously expected and a
general lack of dendrites (large snowflakes). Most of the reports
from late this afternoon/early evening have been in the 1.5 to 3.5
inch range, though much higher amounts up to 7 or 8 inches have
been reported in parts of the MKX/ARX forecast areas.

The snowfall to water ratio here at NWS GRB was near 10:1 when we
took our last observation at 6 pm, and this is much lower than
expected. As a result, have lowered the snowfall to water ratios
for the rest of the evening, especially over the southeast half of
the forecast area. So, despite not making significant changes to
QPF, additional snow accumulations have trended down. We are now
calling for additional accumulations of 2 to 3 inches in northern
WI, and 3 to 5 inches (locally higher due to lake-enhancement
near the lakeshore) in central, east central parts of far
northeast WI. Think most of northern WI will see totals in the 3
to 5 inch range, while locations farther south reach 5 to 9
inches.

No changes were made to the areal coverage or timing of the
ongoing advisory and warning headlines. Given the more moist
character of snow, especially in the southeast part of the CWA,
blowing snow should have less of an impact when the winds
increase tomorrow.

&&

.KEY MESSAGES...

- Ongoing winter storm continues to impact holiday weekend travel
  across northeast Wisconsin through late tonight where Winter
  Storm Warnings and Winter Weather Advisories are in effect.
  Snowfall totals of 6 to 11 are expected in the Winter Storm
  Warning area, with lighter amounts to the north.

- Hazardous travel conditions will likely persist into Sunday.
  While the snow will end Sunday morning, northwest winds gusting
  to 25 to 35 mph will cause some blowing and drifting snow,
  especially in open areas and on east-west oriented roads.

-  Much colder air will arrive for the start of next week. Wind
   chills may fall to 10 below zero or colder Monday morning with
   below normal temperatures continuing through next week.

&&

.DISCUSSION...
Issued at 331 PM CST Sat Nov 29 2025

Short Term (Today through Sunday):

Surface low across south-central Iowa is expected to move to
near Chicago this evening, then into lower Michigan on Sunday
morning. Snow will continue through the evening, which could
be heavy at times as main system moves across the region.

Meso models also depicting convective elements over Lake Michigan
moving onshore with persistent easterly flow to help enhance
snowfall totals as well. Lake to 850mb temperatures differences
14-16C noted and deep dendritic snow growth zone should lead
to an efficient snowfall. Still watching our southern counties
with an east-west band of heavier snow due to fgen band that
could boost totals in this region. Continued to use the lower
snow ratios, although snowfall totals were a tad bit higher due
to minor differences in QPF values. It should be noted that the
meso-models are showing several bands, which will result in
variable storm snowfall amounts near Lake Michigan.

The snow should taper off from west to east overnight, except
across the far north where snow showers or flurries will linger
into Sunday due to northerly flow off Lake Superior. Contemplated
on extending the Winter Storm Warning for the Fox Valley and
lakeshore due to strong northwest winds Sunday morning as snow
will exit the region around 12z. It is possible that a Winter
Weather Advisory may be needed for portions of northeast WI after
the Winter Storm Warning expires at 6 am due to the drifting/blowing
snow.

Long Term (Sunday Night through next Friday):

The first subzero temperatures of the season are possible Monday
morning across the north. Meanwhile, a system passing to the
south of the area Monday night that could bring an inch of snow to
central and east-central WI. A brief warm is expected on
Wednesday ahead of the next arctic front. This system will bring a
chance of snow Tuesday night and Wednesday. Colder air returns on
Thursday with lingering chances of light snow across the north
Friday and Saturday. Except for Wednesday, temperatures will run
well below normal each day.

&&

.AVIATION...for 06Z TAF Issuance
Issued at 1054 PM CST Sat Nov 29 2025

Poor flying conditions expected overnight due to IFR vsbys
in light to moderate snow, and CIGS in the MVFR/IFR categories.
Pockets of moderate snow will be most likely in the Fox Valley for
the first couple hours of the new TAFs, and through the overnight
hours near the lakeshore. Snow will gradually taper off from west
to east early Sunday morning, except across the far north where
lake-effect snow showers should linger into the day. Behind the
system, gusty north to northwest winds could produce some
localized blowing and drifting of the new snow, though a wetter
consistency of the snow should mitigate this in the Fox
Valley/lakeshore areas. Winds should gradually subside Sunday
afternoon. Conditions should improve to VFR at most locations
during the late morning/early afternoon on Sunday as ceilings rise
or break up.

Plowing operations will be needed at all airport sites.

&&

.GRB WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 6 AM CST Sunday for WIZ005-010>013-
018-019-021.

Winter Storm Warning until 6 AM CST Sunday for WIZ020-022-030-
031-035>040-045-048>050-073-074.
&&

$$

UPDATE.........Kieckbusch
DISCUSSION.....Eckberg
AVIATION.......Kieckbusch