829
FXUS63 KDLH 081146
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
546 AM CST Mon Dec 8 2025

.KEY MESSAGES...

- A Winter Weather Advisory remains in effect for the Arrowhead
  and now includes Koochiching, Itasca, and the northern 2/3 of
  St. Louis county for 2 to 5 inches of snow. Around 1 to 3
  inches of snow are expected elsewhere. Most of the snow will
  fall from late afternoon through early Wednesday morning.

- More snow is expected Tuesday afternoon through early
  Wednesday with potential for widespread accumulating snow and
  difficult travel possible for the Tuesday afternoon and early
  Wednesday morning commute. A Winter Storm Watch was issued
  generally along and south of US-2.

- Additional light snow episodes are possible late-week into
  next weekend along with cold air and below-zero temperatures
  likely at night.

&&

.DISCUSSION...
Issued at 424 AM CST Mon Dec 8 2025

Main focus for the next 48 hours are the two clippers which
will produce measurable snow across the Northland. As of 10Z
today light snow from a weak wave propagating southeastward
across the area is moving out of central Minnesota and the I-35
corridor. Snow accumulation early this morning will be light,
less than half an inch.

Southerly winds aloft will allow for weak isentropic ascent
over the I-35 corridor today. There may be sufficient lift for
flurries to develop. A convergence band of lake-effect snow
developed over the southwest arm of Lake Superior between 08Z
and 10Z. We expect this band to lift northward this morning and
eventually bring light snow to portions of the North Shore
generally to the northeast of Silver Bay. Onshore flow should be
sufficient for accumulating snow particularly over southern
Cook County this morning and afternoon ahead of the clipper. A
Winter Weather Advisory goes into effect for those areas at 9
am.

The first of the two main clippers will move across the region
this afternoon and tonight. NBM mean 24 hour snowfall ending 12Z
Tuesday shows accumulation of 1 to 3 inches from NW Minnesota
to western Upper Michigan. The 50th and 75th percentile values
shift the axis a bit farther south. The 50th percentile values
are about half an inch lower than the mean and the 75th
percentile is a few tenths higher than the mean. Overall think
the distribution is overdispersed. High-res guidance shows a
zone of 0.5 to 1 inch per hour snow rates late this afternoon
and evening from NW MN through the Arrowhead. It appears those
snow rates would reside over any given location for less than an
hour to 3 hours. If those rates do develop, the forecast snow
totals would be a bit low. 00Z HREF probabilities of 1 inch per
hour rates are only as high as 60 percent and those values exist
over a relatively small area. Most of the probabilities of 1
inch per hour rates are in the 10 to 30 percent range.

Rapid snow accumulation centered around the evening commute
will likely create greater impacts than the overall snow totals
would suggest. For that reason we opted to extend the Winter
Weather Advisory west to Koochiching and Itasca counties. Snow
will taper off from west to east early Tuesday morning. We will
then have about a 12 hour break before the next and stronger
clipper arrives.

The second clipper moves into the region Tuesday morning
through Tuesday afternoon. This wave will be accompanied by a
meridional moisture feed from a Pacific Northwest atmospheric
river. There are a few more forecast challenges with the second
system than the first. There are questions about the poleward
extent of warm air advection ahead of the system. Thus there is
a potential for rain or freezing rain near Brainerd to Pine City
as precipitation begins. Regardless of how the precipitation
starts, snow will be the dominant precip type within an hour or
two of onset. The track of that system will be farther south
than the first system. Thus the axis of highest snow amounts
will extend from near Grand Forks to Brainerd to Pine City to
Park Falls.

NBM mean 48 snowfall ending 12Z Thursday (thus excluding the
first clipper) features an axis of 3-5 inches of snow from NW MN
to NW WI. Meanwhile the 50th percentile is a little narrower
with that axis with slightly higher values. Looking at the 75th
percentile raises the Brainerd Lakes, parts of the I-35
corridor, and most of northwest Wisconsin above 6 inches. With
the recent jog southwestward of the 00Z GFS solution, we think
the NBM probabilities are probably overdispersed. The axis of
highest snow totals is likely too broad because of the influence
of the GFS. The probability of 6 inches or more of snow from
that system across central Minnesota to central Wisconsin is
likely higher than what the NBM values represent. There will
also be a potential for banding and a period of 1 inch per hour
or greater snow rates Tuesday afternoon and evening. 00Z NAM
reveals a corridor of 10-12 microbar per second omega
propagating southeastward with time Tuesday afternoon and
evening. While the greatest ascent will likely be warmer than
the dendritic growth zone, seeding of dendrites from above will
likely lead to efficient crystal growth. Snow ratios during the
period of heaviest rates of between 8 and 13 to 1 are likely.

With the potential for high snow rates and greater moisture
availability with the second system, we chose to issue a Winter
Storm Watch from central Minnesota southeast across the I-35
corridor and over all of northwest Wisconsin.

Snow from the second clipper will taper off early Wednesday
morning for most locations. Lake-effect snow showers and wrap
around light snow will persist over northwest Wisconsin through
the day Wednesday. Additional snowfall over much of northwest
Wisconsin after 6 am Wednesday will be less than an inch except
for the snowbelt areas which could see an additional inch or
two.

In the wake of that clipper, we can anticipate a brief period
of quieter weather. Another wave will move across the Plains and
Upper Midwest Thursday night and Friday. Another bout of
accumulating snow is not out of the question, although as of
this morning the greatest potential for accumulation will be
over the southern third of Minnesota. A surge of Arctic air will
follow that system for the weekend which will raise the
potential need for cold weather headlines.

The wavy pattern persists into next week with another chance of
accumulating snow early next week.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 546 AM CST Mon Dec 8 2025

VFR conditions are forecast this morning ahead of an
approaching clipper. Ceilings gradually trend lower today and
snow moves in from the west late this afternoon. Visibility and
ceilings will drop to IFR/LIFR in heavier snow bands for a
period of about 1 to 3 hours. Ceilings will rise a bit after the
heavy snow passes. IFR ceilings will persist through 12Z
Tuesday. Another round of snow arrives Tuesday afternoon and
will bring another period of IFR/LIFR conditions.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 437 AM CST Mon Dec 8 2025

Winds will continue to back southwest this morning and
strengthen tonight ahead of an approaching clipper system. Wind
speeds, gusts, and wave heights will increase and become
hazardous to smaller vessels this afternoon and tonight. Snow
will spread eastward over the water which will reduce visibility
to less than 1/2 mile at times. Winds quickly veer northwest
after midnight tonight and will gradually weaken Tuesday
morning.

Another fast-moving clipper will pass to the south of the lake
Tuesday afternoon through Wednesday afternoon. Winds will back
northeasterly and strengthen Tuesday evening and will become
hazardous for small craft once again. Gales are possible Tuesday
night and Wednesday morning between Silver Bay and Grand
Portage. There is about a 50 to 70 percent chance of gales to at
least 35 knots during that time. A Gale Watch is now in effect
for that time period. Winds will gradually back northwesterly by
Wednesday afternoon and will gradually diminish.

For the open water discussion, refer to the NWS Marquette Area
Forecast Discussion at weather.gov/mqt.

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...Winter Weather Advisory from 3 PM this afternoon to 6 AM CST
     Tuesday for MNZ010>012-018>020-026.
     Winter Weather Advisory from 9 AM this morning to 6 AM CST
     Tuesday for MNZ021.
     Winter Storm Watch from Tuesday afternoon through late Tuesday
     night for MNZ025-033>038.
WI...Winter Storm Watch from Tuesday afternoon through late Tuesday
     night for WIZ001>004-006>009.
MARINE...Small Craft Advisory from 9 AM this morning to 3 AM CST
     Tuesday for LSZ121-140>148-150.
     Gale Watch from Tuesday evening through Wednesday morning for
     LSZ140>142.

&&

$$

DISCUSSION...Huyck
AVIATION...Huyck
MARINE...Huyck