848
FXUS63 KFGF 072032
AFDFGF

Area Forecast Discussion
National Weather Service Grand Forks ND
232 PM CST Sun Dec 7 2025

.KEY MESSAGES...

- On Monday, a weak system will produce a Trace to 2 inches of
  snow across portions of northeastern North Dakota into
  northwestern MN.

- A stronger storm system arrives on Tuesday, bringing a wide
  range of potential winter impacts from accumulating snow and
  mixed precipitation to high winds.

- Much colder temperatures will arrive late week, with a 60%
  chance that wind chills drop to -30F or colder.

&&

.DISCUSSION...
Issued at 232 PM CST Sun Dec 7 2025

...Synopsis...

Northwest flow remains in place over the Northern Plains. With cold
air entrenched to the northeast and milder Pacific air to our west,
we will remain stuck on a wavering baroclinic zone for much of
the week. This will lead to an extremely active pattern, with 3
waves passing through in the next 48 hours alone. Ensembles have
advertised for days that the Tuesday shortwave will be the
strongest in this parade of clippers, bringing the potential for
heavy snow and much stronger winds then any of the other waves.
Therefore, we expect the highest winter impacts to be tied to
the Tuesday system. Beyond Tuesday ensembles hint at another
wave on Thursday, followed by a powerful punch of arctic air.
This will result in temperatures dropping into the double digits
below zero area wide, bringing what could be the first cold
weather headlines of the year.

...Light Snow on Monday...

A mid level shortwave located just west of our FA has resulted in a
band of snow over central ND this afternoon. As we go into the
evening and overnight hours, it will continue to propagate
eastward, bringing light snow to much of the FA. On this
shortwaves heels is yet another currently to our north in
Canada. This wave will overspread the FA in a broad warm air
advection regime, which will promote yet another area of light
snowfall on Monday, mainly in northeastern ND into northwestern
MN. When looking at the 25th to 75th percentiles, snowfall will
range from a trace to 2 inches generally along and north of
Highway 2, highest near the Lake of the Woods.

...Strong Tuesday System...

A strong area of low pressure will form in the lee of the Canadian
Rockies Monday night. With a over 100 knot jet streak, this low will
rapidly deepen and dig to the southeast, tracking through the FA
Tuesday into Tuesday night. Ensembles have been latched onto
its general track for several days now. However, that does not
mean this is a straightforward forecast.

First, a period of strong warm air advection will overspread the FA
Monday night into Tuesday. This will cause several forecast
challenges. 1) A warm nose aloft will complicate precipitation type,
especially along and south of Highway 200. This will likely lead to
a period of freezing rain Tuesday morning, especially before
sunrise. Ensemble probabilities for freezing rain now show a stripe
from south of Devils Lake through Fargo down towards Fergus Falls.
Timing wise it may impact the Tuesday morning commute, but as
temperatures warm through late morning into the afternoon,
impacts from freezing rain will rapidly decrease. 2) The dual
combination of warm temperatures and rain/freezing rain will
crust over the existing snowpack in southeastern ND/west
central MN. This wrench in the forecast introduces significant
uncertainty about how much blowable snow at least in the
southern FA there will be once winds increase behind the cold
front Tuesday evening.

To the north of the low, strong synoptic forcing and a band of
frontogensis look to set up an arc of accumulating snowfall.
Ensembles have been consistent in outputting a stripe of QPF around
0.5", running from somewhere in the Devils Lake Basin southeastward
into MN. The handful of CAMs that are now in range show
slightly higher QPF totals then this, which makes sense since
they should be resolving the mesoscale forcing better then their
global counterparts. Assuming a lower snow to liquid ratio
based on warmer sounding profiles and less residence time in the
DGZ, snowfall total outputs are a broad 3 plus inches, with a
stripe of 6 inches. Where exactly in the watch area this
heaviest band sets up still remains uncertain.

A final complicating factor is the wind. As the low propagates
east and the cold front passes, winds will increase dramatically
Tuesday evening. Winds will be strongest across southeastern
ND. However, this is the area that will have a crusted over
snowpack and receive the least new snow. Further north in the
central and northern Red River Valley, there will be new
snowpack sufficient to blow around, but winds will not be quite
as strong, as the core of the cold air advection dives too far
to the south. Winds will turn due northerly on Tuesday night,
which at least in the valley should aid in keeping them
elevated. In turn, predictability of visibility reductions tied
to blowing snow is low at this time, as for every factor that
would aid in more severe visibility reductions, there is another
factor that detracts.

Therefore, we have issued a winter storm watch for much of the FA
from Tuesday morning through early Wednesday morning. It is a
little broad, and the type of impacts at each individual point
(ice vs snow vs blowing snow) remain a bit in question, but this
is at least a starting point in showing what areas have the
highest probability of seeing winter impacts. The handful of
counties in the far south without a headline in effect will be
revisited on future shifts as predictability increases, as
uncertainty right now lies in if headlines will need to be
geared towards winter or wind impacts, and the degree of
severity (advisory vs warning) for each.

...Late Week Cold...

The coldest air of the season will spill down from Canada to end the
work week. NBM is already showing the probability for wind chills of
-30F or lower (cold weather advisory criteria) at 60%. Uncertainty
around where the deepest new snowpack will reside, cloud cover and
winds will eventually determine how cold both temperatures and wind
chills are able to fall.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1132 AM CST Sun Dec 7 2025

Two weak systems will pass through during the TAF period, each
bringing light snow. The first is currently over central ND,
pushing eastward. It will arrive at KDVL late this afternoon,
then pass through the Red River Valley during the evening hours.
There will be a little break, before another system passes
through on Monday, mostly impacting northern terminals. Ceilings
will vary from VFR to start the TAF period, falling to MVFR
overnight. MVFR will likely persist into Monday, but it will be
a close call as ceilings will teeter on the edge of VFR at KDVL
and KFAR.

&&

.FGF WATCHES/WARNINGS/ADVISORIES...
ND...Winter Storm Watch from Tuesday morning through late Tuesday
     night for NDZ006>008-014>016-024-026>030-038-039-054.
MN...Winter Storm Watch from Tuesday morning through late Tuesday
     night for MNZ001>005-007>009-013>017-022>024-027-028-
     030>032.

&&

$$

DISCUSSION...Rafferty
AVIATION...Rafferty