457
FXUS63 KDLH 091146
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
546 AM CST Tue Dec 9 2025

.KEY MESSAGES...

- Snow and freezing drizzle will taper off this morning.

- The next clipper will arrive late this morning through the
  afternoon and will bring heavy snow to areas generally south
  of US-2.

- Winter Weather Headlines were extended north in Minnesota and
  the Winter Storm Warning in NW WI was expanded. End times from
  the I-35 corridor east were extended.

- A period of several hours of heavy snow with rates around 1
  inch per hour is expected late this afternoon through this
  evening.

- Freezing drizzle may follow the snow early Wednesday morning.

- Cold temperatures and additional chances of precipitation are
  expected later this week into next week.

&&

.DISCUSSION...
Issued at 418 AM CST Tue Dec 9 2025

SUMMARY OF HEADLINE CHANGES

- Winter Weather Advisory for portions of north-central and
  northeast Minnesota remains in effect until 6 AM today.

- Winter Weather Advisory for this afternoon and tonight was
  adjusted north to include Itasca, central St. Louis, and
  southern Lake county areas.

- Winter Storm Warning was expanded north in northeast
  Minnesota to include northern Cass, northern Aitkin,
  Carlton/South St. Louis counties.

- Winter Storm Warning timing for Pine and Carlton/South St.
  Louis counties was adjusted. Starts at 20Z today and ends at
  12Z Wednesday.

- Winter Storm Warning for Burnett County was extended until
  15Z Wednesday.

- Winter Storm Warning in northwest Wisconsin was expanded to
  include Douglas, Washburn, Sawyer, and Price Counties. Time
  was extended to 15Z Wednesday.

- Winter Weather Advisory for Bayfield, Ashland, and Iron
  counties was extended to 18Z Wednesday.

----------

The first of two clippers is departing the Northland this
morning. As the higher altitude clouds depart, the lower
altitude liquid droplet clouds remain. Therefore freezing
drizzle has been observed after snow ended across much of the
Northland. GOES-East night microphysics product reveals clear
skies northeast of a line from near International Falls to near
Two Harbors. Another area of low stratus was moving
southeastward toward the Arrowhead and may provide another burst
of freezing drizzle. Minor ice accumulations are possible from
the freezing drizzle which may make roads, sidewalks, bridges,
and elevated surfaces slippery. Otherwise look for conditions to
improve for a time this morning before the second clipper
arrives.

The big story with this forecast package is the second clipper
system which will arrive from the west this afternoon and
tonight. The system is fast moving with complicated dynamics and
abundant moisture available from an atmospheric river which is
impacting the Pacific Northwest. This forecast is definitely not
easy and has a high potential to bust both to the low side of
forecast snow amounts north of US-2 and to the high side south
of US-2. The NAM solution is farther north today than yesterday
morning while the global models have come into better alignment.
Thaler QG omega is quite strong from all the models with an
area of 20 to 30 mb/hr ascent this afternoon and tonight.
Frontogenesis will be aligned generally along the same axis. NAM
and GFS cross sections reveal an area of 8 to 12 microbar per
second omega co-located with the strongest FGEN and ample
moisture. Very efficient snow crystal growth is expected where
those parameters intersect. Look for several hours of 0.5 to 1.5
inch per hour snow rates generally near and south of US-2.
Those rates should move across central Minnesota between 3 and 6
pm and over northwest Wisconsin between 6 and 10 pm.

On the other hand, the global models are bringing in strong dry
air advection on the north side of the low track which will
likely eat into snow totals. The greatest impact to snow totals
should be north of the zone of strongest ascent, mainly along
and north of US-2. Snow amounts in those areas may end up
several inches too high if there`s enough dry air to limit
snowfall to only a few hours. Grand Rapids to Duluth are right
in the zone where there may be a tight gradient in snow amounts.
If the strongest forcing develops just a little farther south
(20 to 40 miles) the higher snow amounts will be in MPX`s area.

High-res CAMs are pointing to a convergent band of snow
developing over the western arm of Lake Superior early Wednesday
morning. The convergence is subtle. As we saw this morning and
a few weeks ago, the CAMs do an OK job catching onto these
narrow and usually transient bands of convergence and subsequent
snowfall. The consensus is for the band of snow to impact the
Twin Ports from around 2 am until 4 or 5 am Wednesday. That
would be after the main synoptic snow had ended. The additional
snow accumulation from that band has the potential to boost the
event snow totals at Duluth. The convergent band will continue
to sweep southeastward during the morning adding to snow totals
in northwest Wisconsin. Lake-effect snow may develop as winds
turn northwesterly Wednesday morning which would allow light
snow to persist over Bayfield, Ashland, and Iron counties
through the morning.

There is also a potential to see a period of freezing drizzle
Wednesday morning as the upper-level moisture advects east
faster than the low-level moisture, a scenario similar to this
morning. If the freezing drizzle develops and persists,
headlines may need additional extensions tomorrow morning.

In the end snow amounts have ticked up a little bit with this
forecast. We now have a swath of 5-7 inches from Cass County to
Price County. For the Twin Ports, Cloquet and areas south along
I-35 have the greatest potential for higher end amounts. Duluth
may only see 4-6 inches. There are some challenges in where the
enhanced upward vertical motion will develop. One of the models
keeps Duluth largely out of the snow!

We extended the headlines for this afternoon and Wednesday
north one tier of counties in Minnesota and extended the Winter
Storm Warning east into Wisconsin. Since Ashland, Bayfield, and
Iron counties have higher snow thresholds for a warning, we left
them in an advisory. We also added a few hours to the
Carlton/South St. Louis, Pine, Burnett warning. The I-35
corridor is now until 6 AM Wednesday and Burnett is 15Z along
with the rest of the NW WI counties in the warning. We extended
the Advisory for NW WI until 18Z to account for additional light
snow and lake effect Wednesday morning.

Attention then turns to the latter portion of the week. Another
clipper is forecast to pass to our south Thursday and early
Friday. The passage of that low pressure system will
reinvigorate the cold air advection over the Northland for
Friday into the weekend. By Saturday we may see highs straddling
zero. Cold weather headlines may be needed later this week into
the weekend. The cold air will bring another chance of light
snow Friday. The clipper parade persists into next week with
another shot of snow Sunday night and Monday. Some models are
indicating a warming trend Tuesday and Wednesday which would see
temps above normal.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 546 AM CST Tue Dec 9 2025

Areas of freezing drizzle and flurries persist this morning and
are expected to dissipate by late morning. GOES-East night
microphysics imagery reveals an area of potential freezing
drizzle which persists for several hours after snow ends.
Ceilings may briefly improve to MVFR before the next clipper
arrives late this morning into the afternoon. At the moment I
think that`s unlikely. That system will bring IFR/LIFR ceilings
and visibility. High snow rates of 0.5 to 1.5 inches per hour
are expected from 21Z to around 00Z at BRD. There could be a
period of freezing drizzle after snow ends.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 428 AM CST Tue Dec 9 2025

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 of 35 to 40 knots
are forecast from Taconite Harbor to Grand Portage where a Gale
Warning is in effect. Small Craft Advisories go into effect at
10 pm tonight for the remainder of the waters. Wind gusts of 25
to 30 knots are expected. Waves will build to 3 to 10 feet over
the southwest arm and along the waters of the South Shore. As
the clipper departs on Wednesday winds will back northwesterly
and diminish. Small Craft Advisories will likely be needed for
portions of the North Shore from late Wednesday morning through
Wednesday evening. Cold air moving over the high terrain will
likely lead to katabatic winds from Silver Bay to Grand Portage.
Wind and waves will then relax for Thursday before increasing
again on Friday.

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 until 6 AM CST early this morning for
     MNZ010>012-018>021-026.
     Winter Weather Advisory from noon today to 3 AM CST Wednesday
     for MNZ018>020-026.
     Winter Storm Warning from noon today to 3 AM CST Wednesday for
     MNZ025-033>036.
     Winter Storm Warning from 2 PM this afternoon to 9 AM CST
     Wednesday for MNZ037-038.
WI...Winter Storm Warning from 3 PM this afternoon to 9 AM CST
     Wednesday for WIZ001-006>009.
     Winter Weather Advisory from 3 PM this afternoon to noon CST
     Wednesday for WIZ002>004.
MARINE...Small Craft Advisory from 10 PM this evening to 10 AM CST
     Wednesday for LSZ121-142>148-150.
     Gale Warning from 10 PM this evening to 10 AM CST Wednesday
     for LSZ140-141.

&&

$$

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