153
FXUS63 KBIS 230343
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
943 PM CST Fri Nov 22 2024

.KEY MESSAGES...

- There is a 50 to 90 percent chance of light accumulating snow
  this weekend across the north, with chances decreasing
  towards the south. There is a 40 to 60 percent chance of at
  least 2 inches of snow along the Canadian Border.

- Below average temperatures are expected through this weekend
  and into next week. Highs will mainly be in the 20s and 30s,
  and lows mainly in the single digits to teens above zero.
  Monday will be colder, with highs in the teens and 20s and
  overnight lows in the single digits above and below zero.

- Even colder temperatures will be possible during the
  Thanksgiving Holiday weekend, with forecast daytime highs in
  the single digits above some locations, and overnight lows
  below zero. Well below zero wind chill temperatures are also
  possible.

&&

.UPDATE...
Issued at 941 PM CST Fri Nov 22 2024

Snow has spread east a bit further than previously forecast,
but over most locations it remains quite light. For late evening
update have broadened out snow chances, but in line with latest
guidance have the snow gradually tapering off as the night goes
on.

UPDATE
Issued at 615 PM CST Fri Nov 22 2024

Light snow is starting to nudge into northwest North Dakota, on
track with latest forecast. Will have to keep an eye on how this
evolves over the next few hours as latest guidance has shown
some differences on its evolution, with some models having it
die out sooner than forecast. Otherwise, remainder of forecast
continues to be in good shape.

&&

.DISCUSSION...
Issued at 211 PM CST Fri Nov 22 2024

Early this afternoon, a weak shortwave was noted on water vapor
satellite imagery, moving through the region in low amplitude
northwest flow aloft. An upper level ridge axis will move closer
to the Montana/North Dakota border tonight behind another weak
shortwave. Some of the guidance does suggest some decent
midlevel frontogenesis but it is not forecast to lineup well
with the diffuse synoptic forcing. Thus, we can expect medium to
high chances (40 to 70 percent) of light snow across the
northwest late this afternoon and into the evening hours but
chances will quickly fall off when the wave moves into the
central part of the state overnight and the frontogenesis washes
out. Light accumulations associated with this wave will
generally be confined to the northwest and will likely range
from a dusting to around an inch at most. Lows tonight will
range from the single digits above zero north (below normal for
this time of year) to the mid to upper teens south (around
normal to slightly below normal).

The ridge axis then moves across the state on Saturday which
should keep western and central North Dakota dry for most of the
day (the exception possibly across the northwest where we could
see some light warm air advection snow in the afternoon). We
will gradually transition to southwest flow aloft from west to
east as the next trough approaches. An upper low will close off
near the border of Alberta and southern Saskatchewan Saturday
night, bringing the next chances for light snow accumulations
through Sunday. The trend continues to keep most of the synoptic
forcing and frontogenesis north of the International border
with only minor snowfall accumulations in our area as the trough
passes through. While we will continue to see medium to high
chances (50 to 90 percent) for light snow along and north of
Highway 2, chances for 4 inches or greater still only max out
around 30 percent right along the Canadian border through
Sunday. Further south, mainly in the Highway 200 to Highway 2
corridor, expect only low to medium chances (20 to 50 percent)
for light snow. With all that said, the best guess is that we
will see a swath of 1 to 3 inches of snow (NBM 25th to 75th
percentiles) along and north of Highway 2 tonight through Sunday
and that may even be a bit on the high side. Confidence in
advisory level winter weather over the weekend continues to
lower so we will take the mention out of the Hazardous Weather
Outlook for this forecast package.

After the trough moves out of our area by Monday morning, we
generally transition back into mean northwest flow aloft through
the rest of the period. A few weak waves will quickly move
through the flow at times during the upcoming work week, but for
now these waves are only leading to spotty low chances of light
snow (10 to 20 percent). The bigger story will likely be the
much colder temperatures, especially around Thanksgiving and
into the holiday weekend. Highs on Saturday and Sunday will
range from the lower 20s to the lower 30s. Then on Monday
morning, we will see lows ranging from around zero northwest to
around 10 above southeast. Highs on Monday will then only range
from the lower teens to the lower 20s and we could see below
zero low temperatures northwest and north central Tuesday
morning. Further south, lows will only max out around 5 to 7
above. We may moderate a bit Tuesday and Wednesday afternoon
(highs in the teens north to the 20s and lower 30s south) but an
even colder airmass is expected to move in on Thanksgiving and
into the holiday weekend. By Friday morning, we could see lows
in the 10 to 15 below zero range across the north, maxing out
only in the lower single digits above zero over the far south.
The one caveat is that there are still some decent NBM
temperature spreads as we move towards the end of the week, but
it is basically the difference between cold and very cold for
this time of year. For example, the NBM spread for the low
temperature at Minot on Friday morning ranges from 2 above zero
(75th percentile) to 10 below (25th percentile). Either way,
wind chills should be well below zero most mornings through the
week across all of western and central North Dakota. Looking
ahead, the well below normal temperatures should continue
through the weekend. Stay warm and be careful if traveling!

&&

.AVIATION /00Z TAFS THROUGH 00Z SUNDAY/...
Issued at 615 PM CST Fri Nov 22 2024

Widespread MVFR with localized IFR ceilings continue to spread
through much of western and central North Dakota this evening,
though many parts of north central North Dakota including the
KMOT terminal may remain VFR. In the meantime, some snow is
currently entering far northwest North Dakota, resulting in reduced
visibility to MVFR and IFR levels. The snow will dissipate
later tonight as it moves east. Ceilings over most locations
will gradually improve Saturday, but may remain VFR over
northwest North Dakota including the KXWA terminal as another
disturbance approaches, with some snow developing.

&&

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

&&

$$

UPDATE...JJS
DISCUSSION...ZH
AVIATION...JJS