184
FXUS63 KDLH 062020
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
220 PM CST Sat Dec 6 2025

.KEY MESSAGES...

- Arctic air this weekend will keep highs in the single digits to
  low teens with overnight lows below zero.

- Active weather next week with several clipper systems passing through
  the region. The Tuesday into Wednesday system currently looks
  to be the most impactful with the potential for heavy
  snowfall.

- Another round of arctic air late next week and weekend will
  push highs back down into the single digits to low teens with
  overnight lows below zero.

&&

.DISCUSSION...
Issued at 220 PM CST Sat Dec 6 2025

Today - Sunday:

A strong arctic high pressure centered over Alberta today and into
the Red River Valley on Sunday should keep mainly dry conditions and
colder air over the region under primarily clear skies for most.
There are a few exceptions to this, however. First, is some cloud
cover from the Brainerd Lakes east into inland northwest Wisconsin
through this evening on the northern fringe of a cloud shield
associated with a low pressure system passing well to our south.
Second, are some light snow showers downwind (i.e. southeast) of
bigger inland lakes in Minnesota, especially near the International
Border today through tonight. Third, are South Shore lake-effect
snow showers due to the colder air over a relatively warm (around
40F) Lake Superior water surface. The South Shore lake-effect should
linger into daytime Sunday before coming to an end in Ashland and
Iron Counties Sunday evening as winds turn westerly and drier air
cuts off lake-effect processes. Expect less than an inch of snow
from the inland lake-effect snow showers in northern Minnesota and
generally another 1" to locally 3" of very fluffy snow in eastern
Ashland and northern Iron Counties for today through Sunday.

Temperatures will be well-below average today and Sunday, with highs
both days in the single digits to teens and lows tonight and Sunday
night for pretty much everywhere in the Northland. Some lows tonight
in north-central and northeast Minnesota may even dip below -10F in
areas where skies stay clear and winds remain very light to calm.
This could set up overnight and early Sunday morning wind chills in
the -10F to -25F range, lowest in the Arrowhead and Iron Range.

ACTIVE PATTERN NEXT WEEK:

Monday - Early Tuesday Clipper:

On Monday, the surface high pressure and main lobe of the arctic
airmass will be sliding southeast of the Northland, setting up
southerly return flow into the Northland and moderating
temperatures with highs in the upper teens to mid 20s. Very
light snow is possible late Sunday night into Monday morning as
a weak 500 mb shortwave interacts with weak lift due to warm
advection in a saturated dendritic growth zone. Snow amounts
with this snow look minimal, with the best potential for
measurable snow in the Brainerd Lakes to inland northwest
Wisconsin (20-40% chance).

Then, there is good agreement amongst ensemble surface low tracks
for the first in a series of Alberta Clippers to move through
Northern Minnesota, albeit with a very slight southward shift
relative to previous model runs. This would bring snow to much of
the Northland starting Monday evening, peaking in coverage and
intensity in the late evening and overnight, and then exiting the
Northland to the east by mid to late Tuesday morning. Synoptic lift
from divergence aloft and differential vorticity should aid in a
small period of time in the late evening and early overnight hours
when moderate to locally high snowfall rates would be supported.
Areas generally along and north of US-2 in Minnesota and along the
South Shore are the  with the best potential for 2"+ of snow at 40-
70%, locally 80% along the North Shore. 4"+ probabilities have
dropped off slightly, with 10-20% for the aforementioned areas and
locally 20-30% along the North Shore.

Tuesday - Early Wednesday Clipper:

Quick on the heels of the first Clipper will be a second, stronger
Alberta Clipper diving into Minnesota late Tuesday into early
Wednesday. This system should be much deeper, with ensemble member
forecasts of a surface low with a central pressure ranging from 977-
990 mb. The NAEFS MSLP forecast shows these pressures being near or
at the minimum of the climatology for this time of year. This
system`s moisture will also have Pacific Northwest origins from a
potent atmospheric river. Modification of the moisture as this
system tracks into the Upper Midwest would put forecast PWAT values
near the 90th percentile for the Northland relative to climatology
for early December at around 0.50". The main difference between the
12Z suite and 00Z suite of global ensemble guidance has been a
better clustering in the timing of the low pressure tracks through
Minnesota and Wisconsin from Tuesday afternoon through Wednesday
morning. There is still some room for the track of the center of
this low pressure system to wobble as far north as northern
Minnesota or as far south as northern Iowa late Tuesday
afternoon/evening, but most of the ensemble tracks are through
central Minnesota or the southern half of Minnesota. The exact track
will play an important factor in where the heaviest snow falls and
snowfall amounts for the Northland as strong frontogenetic banding
on the northern side of the surface low and mid/upper-level synoptic
support for strong lift (e.g. differential vorticity and divergence
aloft) should drive periods of heavy snowfall rates (0.5-1" per
hour), particularly late Tuesday afternoon and evening given the
current forecast timing.

There should be a fairly sharp gradient on the northern side of
this banded snow, so a shift of even tens of miles could
drastically change which locations see the highest snowfall
amounts. A more southerly low track across southern
Minnesota/Wisconsin could mean much of northern Minnesota would
only see lighter accumulations, while a low track across central
Minnesota/Wisconsin would place more of the Northland in
moderate to heavy snowfall potential with this system. Current
probabilities for 2"+ of snow are 50-70% generally along and
south of the Iron Range in Minnesota and for all of northwest
Wisconsin. Meanwhile, 4"+ probabilities are 30-55% along and
South of US-2 in Minnesota and for northwest Wisconsin and up to
Silver Bay along the North Shore given initial wind
trajectories off of Lake Superior adding in some lake/terrain
enhancement. Higher snowfall thresholds tail off slowly, with
6"+ probabilities of 20-35% for the same areas as the 4"+
probabilities.

Late Next Week into Next Weekend:

While this second Clipper system will pull out of the area by
Wednesday PM, there should be some lingering snow showers through
much of the day along the South Shore. Global ensemble guidance then
points to the active weather pattern and clipper train continuing
late this week into next weekend as more Alberta Clippers slide
somewhere across the Midwest on Thursday, Friday, and possibly next
weekend. Still plenty of uncertainty regarding the late next week
systems with regards to timing, tracks, and intensities. With that
said, the there are some early indications that the Thursday system
may track far enough south for its associated precipitation to
completely miss the Northland.

One thing that is more certain for late next week into next weekend
will be a return of another cold arctic airmass in the wake of the
Tuesday/Wednesday Clipper. High temperatures will likely return to
the single digits above zero to teens, with overnight lows below
zero.

&&

.AVIATION /18Z TAFS THROUGH 18Z SUNDAY/...
Issued at 1125 AM CST Sat Dec 6 2025

Light lake-effect snow showers/SCT to BKN MVFR cloud bases
persist downwind of the bigger inland lakes today, especially
in far northern Minnesota as evidenced by satellite and
observations. These clouds and possibly (10-20% chance) for very
light snow could impact INL/HIB this afternoon and evening,
though the current northwest wind direction has kept the
coverage of MVFR ceilings and light snow east of those
terminals. Farther south, BRD and HYR continue to see VFR
ceilings around 3500-5000 ft this afternoon on the northern edge
of a cloud shield associated with low pressure passing well to
the south. Expect these ceilings to lift higher this evening,
with some clearing of cloud cover tonight into Sunday morning.

&&

.MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/...
Issued at 220 PM CST Sat Dec 6 2025

Northwest winds pick up, with gusts to 15-20 kt this evening
into midday Sunday. Waves could approach 2-4 ft in the Outer
Apostle Islands. No Small Craft Advisories are expected at the
moment, but may be needed if winds and/or waves increase any
further. Winds weaken and back to southwesterly Sunday evening
and night.

Weather then becomes much more active for Monday into next
week, with multiple clipper systems set to impact the region.
The Tuesday into Wednesday system looks to be a prolific snow
producer. Gusty southwest winds of 20-30 kt are forecast for
Monday, and out of the northeast to north Tuesday night into
Wednesday. There is also a 10-30% chance for gale- force winds
Tuesday night into Wednesday morning for the Outer Apostle
Islands and from Grand Marais to Grand Portage.


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

&&

.DLH WATCHES/WARNINGS/ADVISORIES...
MN...None.
WI...None.
MARINE...None.

&&

$$

DISCUSSION...Rothstein
AVIATION...Rothstein
MARINE...Rothstein