762
FXUS63 KBIS 011234
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
634 AM CST Mon Dec 1 2025

.KEY MESSAGES...

- Well below average temperatures will continue today. Wind
  chill temperatures as low as 30 below zero will be possible
  this morning.

- An active weather pattern is forecast this week, resulting in
  periodic low to medium chances for snow, breezy conditions,
  and moderate to large fluctuations in day-to-day
  temperatures.

- Very cold temperatures are forecast Wednesday night, with
  potential wind chill temperatures as low as 30 below zero.

&&

.UPDATE...
Issued at 631 AM CST Mon Dec 1 2025

Area of mid level clouds moving south/southeast across the state
this morning, associated with a mid level S/WV trough and
frontal boundary. Changes were minimal with this product
issuance.

&&

.DISCUSSION...
Issued at 410 AM CST Mon Dec 1 2025

Currently, north/northwest flow aloft over the Northern Plains
with a S/WV trough moving through the region along with an
associated/subtle sfc trough/frontal boundary. West/southwest
winds ahead of the boundary continues to result in lake effect
snow north and northeast of Lake Sakakawea, as cold air moves
over the much warmer lake waters. As winds become more west
then northwesterly through the AM hours, lake effect clouds and
snow showers will also remain orientated with the mean wind,
becoming east of the lake then southeast of the lake with time
this morning as winds veer. We also continue to observe
occasional low cigs associated with ice crystal in the lower
atmosphere at times at our ASOS and AWOS sites, and this should
continue till mid to late morning. Lastly, wind chill
temperatures have improved a bit from earlier, so opted to
remove mentioning in the HWO.

Above mentioned mid level wave a sfc boundary will push
southeast across the local area this morning, with surface high
pressure developing in their wake. Weak CAA with a low/mid level
northwest flow today, resulting in another day of below normal
temperatures with highs mainly in the teens (lower 20s
southwest).

Model guidance keeps the region in a northwest flow aloft
regime through this week, with embedded waves and frontal
passages periodically moving through. A more defined embedded
S/WV and an associated strong cold front is still favored to
impact the region Tuesday and Wednesday, bringing milder
temperatures on Tuesday (highs 25-35) ahead of the FROPA, snow
chances (30% or scattered) Tuesday afternoon and Tues eve along
and behind the FROPA, followed by another cold period on
Wednesday (highs in the single digits and teens) as strong CAA
surges in behind the wave. NBM was a bit low on POPS Tues
aft/eve considering the forcing depicted, so we (surrounding
WFOs) increased to chance wording. NBM projected wind chills
remain below advisory criteria mid-week, so also opted to remove
this from the HWO. Figured we can always re-raise the flag if
models trend colder and/or stronger with post frontal winds.

This cold period will be brief, as cold sfc high pressure
quickly moves southeast, followed by return flow and another
milder airmass spreading east across the Northern Plains on
Thursday, ahead of another potential S/WV and frontal passage.

EC and GEFS ensembles are indicating decent potential for more
snow for the beginning of next weekend, with each ensemble mean
advertising medium chances (around 60%) for an inch of snow.
Latest NBM (both the 4.3 and 5.0 versions) indicate about a 50%
chance for 2 inches, and low chances (~30%) for up to 4".
Ensemble mean mid level flow is west/northwesterly, with the
mean sfc pattern showing potential for an overrunning flow
regime setting up over the region later this week. Still
several days out, but something worth watching for trends. NBM
temperature spread for next weekend remains large.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 631 AM CST Mon Dec 1 2025

VFR conditions are expected through the 12Z period. Some mid
level clouds will push south across the area early this morning,
with increasing clouds at all terminals tonight. Winds will
gradually shift from southwesterly to more west-northwest
during the 12Z TAF period, remaining at around 10 kts.

&&

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

&&

$$

UPDATE...NH
DISCUSSION...NH
AVIATION...NH