054 
FXUS63 KGRB 291738
AFDGRB

Area Forecast Discussion
National Weather Service Green Bay WI
1138 AM CST Sat Nov 29 2025

Updated aviation portion for 18Z TAF issuance

.KEY MESSAGES...

- Heavy snow is expected across central and northeast Wisconsin
  later today and tonight, where 6 to 11 inches of accumulation 
  is forecast. Locally higher amounts exceeding 12 inches are 
  possible near Lake Michigan, particularly over Kewaunee and 
  Manitowoc counties.

- 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 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.

&&

.DISCUSSION...
Issued at 235 AM CST Sat Nov 29 2025

The latest RAP analysis and satellite imagery show shortwave energy
digging southeast across the central Rockies early this morning, while
flow aloft remains relatively flat across the Midwest. Surface low
pressure is currently centered over southeast Colorado. Ahead of this
low, broad warm and moist advection is occurring in the 850-700mb
layer, supported by a 40 kt low-level jet nosing into Iowa. 
Saturated conditions in the 900-800mb layer are occurring as close
as northeast Iowa and southern Minnesota where snow is occurring.
As the shortwave energy moves from the Rockies across the Plains 
today, the surface low is progged to track from central Kansas to 
the Iowa/Missouri/Illinois border by early evening, eventually 
reaching the central Lower Peninsula of Michigan by 6 am Sunday. 
This track will bring the Colorado Low northeast across the region
over the next 24 to 36 hours.

Short Term (Today through Sunday):

Winter Storm:  Focus of the forecast revolves around snow 
accumulations and impacts as the low pressure system traverses the
region. Ascent will increase today via warm advection driven by a
40-50 kt low- level jet moving into northern Illinois, coupled 
with upper divergence in the right rear quadrant of a jet streak. 
Light snow will gradually spread from southwest to northeast 
across the region this morning through mid-afternoon. High-
resolution CAMs indicate a mid-lake band becoming organized later 
this morning and moving onshore into the northeast WI shoreline by
early afternoon. Precipitation intensity is expected to increase 
significantly across the region this afternoon and evening. It is 
noted that snow ratios were lowered for this forecast as the NBM 
tends to have a high bias in warm advection regimes. While QPF has
trended steady, values were adjusted lower compared to the NBM, 
which was running at the 75th percentile of guidance.

The heaviest snowfall is expected to target east-central Wisconsin
from late this afternoon through this evening. This intensification is
attributed to multi-bands of lake enhancement interacting with a
focused band of frontogenesis that several models develop from
Waushara to Manitowoc counties. Delta-Ts upwards of 15-17C and a
deep dendritic snow growth zone (100-150mb deep) should lead to
efficient snowfall production. Consequently, locally higher 
amounts are possible near Lake Michigan, particularly over 
Kewaunee and Manitowoc counties where totals may exceed 12 inches.
Some amounts could also approach 12 inches from Waushara to 
Calumet counties as well if a mesoscale snowband becomes focused.
The heaviest snow will depart after midnight, with snow ending 
for most areas Sunday morning. However, lake effect snow will 
likely continue in the snow belt of Vilas County, where snowfall 
estimates have increased to the 2-4 inch range. As a result, the 
Winter Weather Advisory has been expanded into Vilas County. 
Regarding timing of headlines, the start time of the advisory has 
been delayed until noon, and the warning until 10 am, as impacts
from snowfall looks minimal prior to those times.

Sunday Impacts and Winds:  While the accumulating snow will 
diminish Sunday morning, travel impacts will likely continue. 
Northwest winds are forecast to increase just as the synoptic snow
departs, with gusts of 30 to 35 mph possible. These gusts will be
strongest where the heaviest snow is expected to fall, 
specifically from the southern Fox Valley to the Lakeshore. 
Blowing and drifting snow is likely, particularly on east- west 
oriented roads. A Winter Weather Advisory may be needed on Sunday 
as the snow diminishes and blowing snow hazards increase; however,
there is currently no need to extend the Winter Storm Warning as 
little to no additional snow accumulation is expected Sunday 
morning. Highs on Sunday will range from the lower 20s to lower 
30s.

Long Term (Sunday Night through next Friday):

A winter-like pattern is shaping up across North America for the next
week, characterized by 5-day means showing ridging off the west coast
and troughing extending from Hudson Bay to the Great Lakes. 850mb
temperatures indicate below-normal readings, setting the stage for the
coldest air of the season thus far. Sunday night into Monday will see
wind chills falling to around 10 below zero, with highs on Monday
in the teens. Looking ahead, the system previously monitored for 
Monday night continues to trend northward, though snow chances 
continue to slowly rise to above 30 percent, highest over east- 
central Wisconsin. By Wednesday, an arctic front will produce the 
next widespread chance for snow (40 percent). Amounts with this 
mid- week system look relatively light, generally an inch or two. 
Arctic high pressure is then expected to build in for late in the 
week.

&&

.AVIATION...for 18Z TAF Issuance
Issued at 1132 AM CST Sat Nov 29 2025

Poor flying conditions expected through tonight due tn snow,
which may be heavy at times, and low CIGS varying from MVFR
or IFR. Conditions may drop below the IFR category due to heavy
snow shower activity along the Lake Michigan shoreline, which
could impact KMTW and airports across Door County. Snow will
gradually taper off from west to east late tonight, except
across the north where snow showers linger into Sunday. Snowfall
totals of 3-6 inches expected across the north, with 6 to 12
inches south of a Wausau to Wausaukee line. Behind the system,
gusty northerly winds expected on Sunday that could produce some
blowing and drifting of the new snow. Winds should gradually 
subside Sunday afternoon. 

&&

.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.
&&

$$

DISCUSSION.....MPC
AVIATION.......Eckberg