375
FXUS63 KDLH 181131
AFDDLH

Area Forecast Discussion
National Weather Service Duluth MN
531 AM CST Thu Dec 18 2025

.KEY MESSAGES...

- A strong clipper will bring a mix of snow, rain, freezing
  rain, and freezing drizzle to the Northland today and tonight.
  Snow may be heavy at times along the Canadian border. Strong
  and gusty winds will further reduce visibility this afternoon
  and tonight where snow is falling or has recently accumulated.

- Confidence in snow totals along the Canadian border is lower
  than earlier forecasts.

- Strong west and northwest winds with gusts of 40 to 55 mph
  will follow a cold front across the area from late this
  morning through tonight. Higher gusts to 60 mph are possible
  in parts of coastal Lake and Cook counties where a High Wind
  Watch is in effect.

- There are additional snow chances this weekend and into next
  week along with variable temperatures.

&&

.DISCUSSION...
Issued at 512 AM CST Thu Dec 18 2025

A strong clipper system was centered over northwest Minnesota
as of 4 AM and will quickly propagate eastward being located
over western Lake Superior by noon today. Dry air after an
initial warm frontal surge of precipitation late last evening
limited precipitation so far early this morning. The majority of
the precipitation with this system is falling north of the
Canadian border at this time. Model solutions continue to point
to an east-southeastward progression of the precipitation shield
through this morning. Additional moisture advection aloft
streaming northward across Iowa and southern Minnesota this
morning should help fill in the gap in precipitation by late
this morning.

The main concerns at this time regard precipitation type and
snow amounts. The dry air overnight and the placement of the
heavier precipitation about 30-50 miles farther north than
expected has already cut into snow totals. Isentropic lift over
central Minnesota and northwest Wisconsin is helping to lower
cloud bases and we think there`s a potential for drizzle and
freezing drizzle before the arrival of heavier precipitation
later this morning into the afternoon. RWIS pavement
temperatures are below freezing as of 4 AM essentially north of
a line from Park Rapids to the northern sections of the Duluth
metro. Air temperatures and temperatures aloft are at or above
freezing. Temperatures aloft remain above the -6 to -8 *C range
(a proxy range for ice nuclei activation) and with a southerly
(warm) wind trajectory, there is unlikely to be antecedent ice
crystals suspended in the air. Thus freezing drizzle or freezing
rain chances are higher than earlier forecasts where pavement
temps are at or below freezing.

Farther south the risk of freezing precipitation is lower
initially. Pavement temps may quickly drop below freezing after
the cold front passes while temps aloft continue to support
drizzle. Once deeper moisture arrives several hours behind the
front, a change to all snow is expected.

There remains a potential for moderate to heavy snow at times
along the Canadian border this afternoon into the evening as
strong ascent and deep frontogenetic forcing pass over those
areas. The precipitation shield north of the low track will need
to sag southward for that to become a reality. As such the
confidence in snow totals is lower than earlier forecast. There
is still a chance of 5-7 inches along the border. The more
likely snow range at this point is probably 1-4 inches.

Blowing snow and reduced visibility is highly dependent on
receiving enough fresh snow. Steep lapse rates this afternoon
and nearly vertical theta-e contours will allow efficient
momentum transfer. Look for wind gusts of 30-50 mph over much of
the region. Portions of the Arrowhead down to the Twin Ports
may see gusts 45 to 55 mph with a few 60 mph gusts along the
North Shore. Since we already have Winter Weather Headlines that
include a mention of the gusty winds, we opted to forego
explicit Wind Advisories.

Conditions quiet down quickly tonight as the fast-moving low
pressure system departs. Temperatures will fall well below zero
over northern Minnesota tonight with areas from the I-35
corridor east across northwest Wisconsin hovering a few degrees
either side of zero. Wind chills of 15 to 30 below zero are
forecast early Friday morning.

Another clipper will scoot eastward across the region Friday
night and Saturday. Warm air advection returns during the day
Friday and temps will rebound into the middle teens to low 20s.
A brief period of light snow is possible late Friday night into
early Saturday morning. Isentropic ascent along the elevated
warm front is possible. Northward moisture advection ahead of
the cold front may be sufficient to support a band of snow
showers along and ahead of the cold front during later Saturday
morning. That snow would impact central MN to northwest
Wisconsin while the earlier snow chances are focused north of
US-2. Guidance has shifted that storm track farther north once
again and snow totals from that clipper should be less than an
inch.

Temperatures trend warmer again later in the weekend into early
next week with highs in the upper 20s to near freezing. A few
more clippers will pass over the region next week, although they
will be moisture starved. The main sensible weather impact will
be changing wind directions and temperature fluctuations and
increased cloud cover. Precipitation chances as of this morning
are scant until perhaps next Thursday night and Friday.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1203 AM CST Thu Dec 18 2025

A strong clipper was centered near GFK as of 18.05Z and will
move across northern Minnesota to western Lake Superior by
18.18Z. Temperatures at the surface were generally above
freezing at the terminals as of 18.05Z (except for CKC and TWM
in the Arrowhead). The first round of precipitation fell as rain
with a few snowflakes mixing in. After this first round of
precip temperatures aloft will remain too warm for snow for at
least the next several hours with rain, drizzle, or freezing
drizzle being the main precip type. Eventually there will be a
change to all snow as temperatures cool later this morning. LLWS
will remain a concern early this morning. HYR will keep the
LLWS risk the longest with winds aloft weakening between 18.09Z
and 18.12Z. Winds will strengthen and turn northwesterly this
morning into early afternoon. The combination of strong winds
and snow will reduce visibility to IFR or LIFR at times. There
is also a risk for snow squalls today which could result in
brief periods of whiteout conditions at the terminals. Winds
will weaken after 19.00Z. Sporadic light snow showers will
persist as long as clouds remain at the terminals.

&&

.MARINE...
Issued at 531 AM CST Thu Dec 18 2025

A strong clipper will move eastward from Challenging conditions
are forecast over western Lake Superior for the next several
days. Fast-moving clippers will bring periods of southerly winds
veering northwesterly and then backing southwesterly again.
There will be lulls in the strong winds between clippers, though
they will be short in duration. Messaging the timing of these
hazards was difficult which is why there are a combination of
multiple Gale Warnings and Small Craft Advisories. Conditions
will be hazardous to small craft between the Gale Warnings.
There is a 30 to 50% chance of storm-force gusts to 50 knots
Thursday afternoon and evening from Grand Marais to Grand
Portage. Arctic air pouring into the region in the wake of a
cold fron Thursday will pose a risk of heavy freezing spray.
Winds and waves will subside for a time Friday before ramping up
again Friday night and Saturday as another clipper propagates
eastward over the region.

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 9 AM this morning to midnight CST
     tonight for MNZ018>020-025-026-033>038.
     High Wind Watch from this evening through late tonight for
     MNZ020-021.
     Winter Weather Advisory until midnight CST tonight for MNZ010-
     011.
     Winter Weather Advisory until 4 AM CST Friday for MNZ012-021.
WI...Winter Weather Advisory from noon today to midnight CST
     tonight for WIZ001-006>008.
     Winter Weather Advisory from noon today to 6 AM CST Friday for
     WIZ002>004.
MARINE...Small Craft Advisory until 2 PM CST this afternoon for LSZ121-
     140>148-150.
     Gale Warning from 2 PM this afternoon to 4 AM CST Friday for
     LSZ121-142>148-150.
     Heavy Freezing Spray Warning from 6 PM this evening to 4 AM
     CST Friday for LSZ121-145>148-150.
     Storm Warning from 3 PM this afternoon to 4 AM CST Friday for
     LSZ140-141.
     Winter Weather Advisory from 9 AM this morning to midnight CST
     tonight for LSZ142.
     High Wind Watch from this evening through late tonight for
     LSZ142.

&&

$$

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