FXUS63 KBIS 111755

Area Forecast Discussion
National Weather Service Bismarck ND
1155 AM CST Mon Dec 11 2023


- A cold front will bring gusty northwest winds and low chances
  for snow across the region this afternoon.

- Sub-zero wind chills are expected across much of western and
  central North Dakota late tonight into Tuesday morning.

- Milder Pacific air returns to the region Wednesday and Thursday,
  with highs forecast in the mid 30s to mid 40s.

- Little to no precipitation is in the forecast for the long
  term period.


Issued at 1127 AM CST Mon Dec 11 2023

No significant changes for the midday update. Cold front has
moved through western and north central ND, and will move through
the south central early this afternoon. A stray snow shower or
flurry is possible along the cold front as it makes it's way
through the area, but not much has fallen and don't expect
anything of consequence before the front exits this afternoon.

UPDATE Issued at 852 AM CST Mon Dec 11 2023

Visibilities have improved From the Turtle Mountain area into the
James River Valley and the advisory will expire at 9 AM. Otherwise
we made some minor adjustments to sky cover today. We did see some
light snow reported at Watford City this hour so there is some
light snow reaching the ground. Based on latest Williston radar we
bumped up pops a bit from Watford City south to the Interstate in
far western ND this morning. Updated text product will be
transmitted shortly.

UPDATE Issued at 553 AM CST Mon Dec 11 2023

Fog continues to slowly erode from west to east across south
central North Dakota early this morning. The Dense Fog Advisory
has been removed from McLean, Sheridan, Wells, Burleigh, and
Emmons Counties. For all other counties, the advisory has been
extended until 9 AM CST. At 545 AM CST, the most persistent dense
fog was located in the southern James River Valley and the
southern slopes of the Turtle Mountains.

Surface analysis shows the cold front now making its way into
northwest North Dakota. Radar returns have shown an increasing
trend over northeast Montana over the past hour, but no snow has
been reported over the observation-sparse area.

UPDATE Issued at 402 AM CST Mon Dec 11 2023

Quick update to add Emmons County to the Dense Fog Advisory.


Issued at 354 AM CST Mon Dec 11 2023

A weak surface trough lies along the Highway 83 corridor early this
morning, with a transient ridge embedded in northwest flow passing
overhead. Areas of dense fog have developed across a large portion
of central and eastern North Dakota, but some erosion of the fog is
taking place as the surface trough slowly meanders eastward. The
most persistent and widespread dense fog has been located throughout
the James River Valley and Prairie Pothole regions, with more widely
scattered dense fog from McLean to Burleigh Counties. Mountrail and
Ward Counties have been removed from the Dense Fog Advisory as
conditions have improved there, but with fog now settling in over
the Turtle Mountains region, Bottineau, Rolette, and Pierce Counties
have been added to the advisory. Additionally, observed and rapid-
refresh model trends suggest that eastern parts of the advisory may
need to be extended beyond the 6 AM CST expiration time, but will
wait until closer in time to make that decision.

A cold front that currently lies from southwest Saskatchewan to Lake
Winnipeg will continue progressing southeastward through the day,
arriving in northwest North Dakota by mid morning and departing the
forecast area to the southeast by early evening. Recent guidance has
backed off on snow potential with the frontal passage, recognizing a
drier mid to upper level air mass coincident with frontal forcing
than previously thought. There are still low probabilities for
measurable precipitation in global ensembles, but now mainly limited
to western North Dakota, which lines up with recent CAM trends.
Additionally, light snow was falling with the frontal passage in
Swift Current, Saskatchewan at 2 AM CST. We will maintain a 20
percent chance of snow with the frontal passage through western and
central North Dakota this morning and afternoon, but our confidence
in the occurrence of snow has lowered, and our confidence in little
to no impacts from snow has greatly increased.

We are still expecting northwest winds gusting to around 40 mph with
and trailing the frontal passage. Deterministic models show a strong
rate of cold air advection with the front, but with only modest
surface pressure rises lagging behind. The strongest winds aloft
also lag behind the initial surge of cold air, with a 45 kt 850 mb
jet progged to expand over north central and eastern North Dakota
later this afternoon and evening. Think there is potential for
surface gusts approaching 50 mph in these parts of the state later
in the day, but it is hard to find any guidance that supports
widespread maximum gusts over 40 mph. Another aspect of the wind
forecast to consider is the potential for blowing snow. Given recent
temperatures and the physical characteristics of the snow that fell
late last week, visibility reductions from blowing snow are very
unlikely, but some ground drifting could occur.

Even with a midday cold frontal passage, temperatures are still
forecast to reach the upper 20s north to mid 30s south. The much
colder air mass with clearing skies is likely to allow temperatures
to fall into the single digits above zero across much of the state
tonight, particularly in the west where a surface high pressure is
forecast to set up by the end of the night. Farther to the east, the
lingering strong pressure gradient will keep northwest winds around
10 to 20 mph for much of the night. Combined with the colder
temperatures, this could lead to wind chills as cold as 10 below
zero. While wind chills this cold are common in wintertime in North
Dakota, the very mild start to the season will likely enhance the
perception of these wind chills being unusually cold.

Surface high pressure will be the dominant weather feature of the
Northern Plains on Tuesday under northwest flow aloft. The NBM shows
confidence in Tuesday being the coldest day of the extended period,
with much of the region still under the influence of the colder air
mass that arrives later today. But even the coldest day will still
feature highs ranging from around 20 northeast to 35 southwest. The
effects of the milder Pacific air flowing down the slopes of the
Northern Rockies will really begin to be felt on Wednesday as a
split upper flow places ridging over Canada and a cyclone over the
Desert Southwest. Small spread in NBM temperature guidance lends
confidence in highs reaching the mid 30s to mid 40s both Wednesday
and Thursday, generally cooler to the north and warmer to the south.

A quick moving shortwave that presents itself in ensemble mean
vorticity fields could pass through the region late Thursday or
Friday, but this does not appear to be a dynamically strong system.
The NBM does favor a very slight cool down for Friday, but with
highs still in the 30s. A transient ridge preceding a stronger
Canadian shortwave could then bring another milder day to start off
the weekend. Though NBM high temperature spread is greater at this
time range, the colder 25th percentile still keeps highs in the mid
30s to mid 40s, and deterministic NBM highs range from around 40
northeast to 50 southwest. Uncertainty increases further on Sunday
due to disparities on the placement and amplitude of the Canadian
shortwave as it approaches Ontario. A more southern track could
bring much colder temperatures and stronger winds to the region,
while a more northern track may result in just a slight cool down.
Either way, the probability of any measurable precipitation not only
from this system but for the entire long term period is very


Issued at 1127 AM CST Mon Dec 11 2023

VFR conditions are expected through the 18Z TAF period.

Cold front is moving through the forecast area at this time.
Northwest winds will increase this afternoon, generally 15 to 20
knots with gust of 25 to 35 knots. Mid level clouds will have
cleared KXWA and KMOT by 18Z. A few hours of mid clouds and
possibly a stray flurry at the southern TAF sites through mid
afternoon, before SKC. Sustained winds will remain breezy but
thinking we should lose the gusts by early evening, then winds
diminish late evening and overnight. Mid and high clouds will
increase from northwest to southeast late tonight through Tuesday