837
FXUS63 KBIS 071236
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
636 AM CST Sun Dec 7 2025

.KEY MESSAGES...

- Another area of light snow is expected to cross the state from
  west to east today, with snow accumulations around one half to
  near 2 inches.

- A more impactful system is forecast Monday night through
  Tuesday night, which may bring a period of freezing rain,
  accumulating snow (highest chances north and east), and very
  strong winds to parts of western and central North Dakota.

- The active pattern continues through the middle of the week,
  with medium chances for another round of accumulating snow
  late Wednesday through Thursday.

- Cold today, followed by above average temperatures Monday and
  Tuesday, then back below average for the second half of the
  week. Friday could be very cold with dangerous wind chills.

&&

.UPDATE...
Issued at 635 AM CST Sun Dec 7 2025

Snow has moved into western North Dakota, as far east as around
Williston to Hettinger as of 630 AM CST. Local radar imagery
and surface visibility observations indicate moderate snowfall
rates, but not lasting for more than an hour or two at any given
location. Current observations and trends have been blended
into the forecast for this update. Overall, the forecast for
today remains on track.

&&

.DISCUSSION...
Issued at 513 AM CST Sun Dec 7 2025

A surface ridge axis across Manitoba and the eastern Dakotas
has allowed early morning temperatures to plummet, with
widespread observed lows around 5 to 20 below zero. There have
been a few instances of wind chills as low as 30 to 35 below,
but winds have mostly remained light except in the far west
where temperatures are now rising. A mid level shortwave/low
level warm front will bring a band of light snow across the
state from west to east this morning through this evening. The
snow was already crossing the Montana border around Beach and to
the south at the time of this writing. QPF threshold
probabilities have been consistently high for at least 0.01",
medium for at least 0.05", and very low for greater than 0.1".
With ensemble snow ratios around 15:1 to 20:1, this yields
medium to high confidence in snow totals around one half to near
2 inches. The NBM has focused its highest snow probabilities
more over the southern half of the state compared to the north,
but we anticipated at least a few tenths of an inch across all
of western and central North Dakota by the end of the day. It
will remain cold for most of the state today, but with a slight
warmup in the west compared to yesterday. Highs this afternoon
are forecast to range from the single digits above zero east to
near 30 in the southwest corner of the state.

Another shortwave crossing central Canada will bring a Pacific
warm front across the state late tonight into Monday morning.
Some CAMs hint at scattered light precipitation accompanying the
warm front, which is a conceptually and climatologically
favored outcome with this type of feature. The light
precipitation would almost certainly fall as freezing rain, but
the probability of of impactful icing at any location is no
greater than 15 percent. As the parent shortwave dives into the
Red River Valley Monday afternoon, some snow or mixed
precipitation could clip the Turtle Mountains, with only low
chances for impactful winter weather at this time. Monday will
be much warmer, with highs mostly in the 30s outside of the
Turtle Mountains and Devils Lake Basin. But it will also be
windy on Monday, with westerly winds around 20 to 25 mph and
afternoon gusts as high as 35 mph.

Confidence continues to increase that a powerful clipper system
will impact the region Monday night through Tuesday night. The
main concern for Monday night into Tuesday morning is the
potential for freezing rain. There are medium to high
probabilities for measurable precipitation across the western
half of the state over this time period, and high confidence in
above freezing temperatures aloft. The uncertainty is with
surface temperatures, which are forecast to steadily rise during
the late overnight and morning hours but could fall below
freezing before the warmup commences. NBM temperature
probabilities prior to sunrise generally show low potential for
sub- freezing surface temperatures in the southwest, and a
medium to high potential elsewhere. This could result in a
period of impactful ice accumulation, but greater than a tenth
of an inch of ice appears highly unlikely. The highest
probabilities for icing are across northwest and central North
Dakota.

00Z ensemble cluster analysis shows little spread in the timing
and track of the surface low, but there are subtle differences
in the QPF/snow fields worth pointing out. Two clusters with
around 55 percent membership show the major axis of highest QPF
cutting through north central North Dakota. The other two
clusters show the same feature shifted farther west into
northwest North Dakota, but the eastern edge of these major axes
in both clusters are near Fargo. The former of these sets of
clusters also contains higher QPF (high chances for at least
0.25") and snow (medium to high chances for at least 3 inches)
probabilities than the latter, both focused across north central
North Dakota. Snow probabilities drop off significantly to the
south and west, where afternoon temperatures are forecast to
rise well above freezing, perhaps as warm as the mid 40s. There
is still a potential for lighter snow in south central North
Dakota with the cold front surging southeastward later in the
day.

The most impactful aspect of the Tuesday system will likely be
very strong winds across western and south central North Dakota.
Every ensemble cluster now has a large area of mean 850 mb
winds in the 55-60 kt range, and deterministic soundings
confirm this is a reasonable approximation for mixing heights.
All requisite ingredients for maximum momentum transfer are
forecast to be present, including strong cold air advection,
strong pressure rises, tightly packed isobars and isotherms,
steep low level lapse rates, and a favorable time of day. If
these forecast signals hold, a High Wind Watch will eventually
be needed.

An active northwest flow pattern is favored to continue through
the rest of the week. The highest chances for accumulating snow
beyond Tuesday are with an upper level jet streak ejecting off
the Northern Rockies Wednesday night into Thursday, but forecast
details on amounts and locations thereof remain uncertain
(there are slightly higher odds to the west compared to the
east). There is however increasing confidence in temperatures
becoming much colder for the second half of the week, especially
from Thursday night through Friday night when ensembles favor a
strong Arctic intrusion. The NBM shows medium to high
probabilities for highs below zero on Friday, along with medium
probabilities for lows around 15 to 25 below both Thursday and
Friday nights. This bitterly cold air mass could be accompanied
by enough of a northwest breeze to cause wind chills to fall to
dangerous levels. Deterministic-based NBM wind chill projections
are currently as cold as 35 to 45 below zero Thursday night
into Friday morning.

&&

.AVIATION /12Z TAFS THROUGH 12Z MONDAY/...
Issued at 635 AM CST Sun Dec 7 2025

Snow with primarily IFR visibility will move across the state
from west to east this morning into the early evening.
Accompanying ceilings are mainly forecast to be MVFR, with
periods of IFR possible across the south. The low ceilings
could persist for several hours after the snow ends, and
possibly through tonight from around KBIS to KJMS. Expect
southeasterly winds around 10 kts today, with a shift to the
west in southwest North Dakota late this afternoon.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

UPDATE...Hollan
DISCUSSION...Hollan
AVIATION...Hollan