678
FXUS63 KBIS 290716
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
116 AM CST Sat Nov 29 2025

.KEY MESSAGES...

- Snow will continue over much of western and central North
  Dakota through tonight before ending later Saturday morning.
  An additional 1 to 3 inches of snowfall are expected, with
  locally higher amounts in parts of south central North Dakota.

- Well below average temperatures are favored this weekend
  into early next week. Wind chill temperatures as low as 25
  below zero will be possible both Saturday night and Sunday
  night.

&&

.UPDATE...
Issued at 114 AM CST Sat Nov 29 2025

Locally enhanced snow continues far south central and southeast,
so issued another Special Weather Statement for locally heavier
snowfall rates for a few hours early this morning there.
Otherwise, the forecast remains in good shape for tonight.

UPDATE
Issued at 953 PM CST Fri Nov 28 2025

A mesoscale banded snow structure largely persists along an axis
from Glen Ullin and Almont to St. Anthony, Hazelton, and Ashley
as of mid evening. Observed snow-to-liquid ratios thus far have
exceeded even forecast expectations, and RAP-based mesoanalysis
output suggests a deep dendritic growth zone with sufficient
omega for efficient snowfall in vicinity of the mesoscale band.
Midlevel lapse rates are also steep, and likely contributing to
the relative narrowness of the band. Other diagnostics remain a
bit nebulous within model simulations, but radar representation
continues to suggest mesoscale forcing continues. We expect that
will gradually become more diffuse as the upper-level jet streak
shifts eastward with arrival of the middle- and upper-level
shortwave trough axis the next few hours, though the latter will
result in widespread and persistent snowfall across western and
central ND overnight. We have deliberated upgrading the counties
most-effected by the mesoscale banding to a Winter Storm
Warning, but with the low-density snowfall and modest winds, the
impacts are not too dissimilar than elsewhere in the advisory.
Moreover, the area covered by a warning would necessarily be
larger than the area impacted by warning-level snowfall, and
it`s also true that the heaviest snowfall is already occurring
at this time, resulting in minimal lead time. So we have chosen
to communicate the area of heavy mesoscale snowfall through
graphics and Special Weather Statements, and have maintained the
Winter Weather Advisory as-is with this update. We will continue
to evaluate the need for any changes, though.

For the broader part of western and central ND, we once again
increased light snowfall chances for a longer period overnight
in respect to upstream observations in MT with widespread 1-3SM
visibility in light snow. Synoptic-scale forcing is expected to
support a general 1 to 3 inches of additional low-density snow
in most areas by Saturday morning, though again locally higher
in the parts of south central ND currently being impacted by the
mesoscale banding. Otherwise, the surface pressure gradient has
been slightly stronger than forecast, which resulted in addition
of patchy blowing snow into the forecast for parts of the area
tonight.

UPDATE
Issued at 643 PM CST Fri Nov 28 2025

A banded snowfall structure persists from roughly Glen Ullin to
St. Anthony, Linton, and Ashley as of 00 UTC, with reports thus
far under the band of up to 3.7 inches of snowfall at Glen
Ullin. Guidance including recent RAP/HRRR simulations have been
suggesting that frontogenesis has weakened in the last few
hours, but radar representation suggests that mesoscale forcing
is persisting in that band, with north-south oscillations to the
band owing to its internal dynamics. The right-entrance region
of a 60-90 kt 300 mb jet streak situated from eastern MT across
northern ND and into southern Manitoba may be effectively holding
this area of enhanced ascent in place, too. Still, given the
expectation of this mesoscale ascent gradually waning, and
climatologically-lower wind speeds with this event, we are not
yet upgrading to a Winter Storm Warning for heavy snow in that
axis. Nonetheless, the upstream shortwave trough and associated
strong Q-Vector convergence aloft is moving through eastern MT
and is expected to cross western and southern ND overnight with
persistent light to moderate snowfall. The KBIS 18z RAOB sampled
a modest dendritic growth zone aloft, but forecast soundings
are consistent in suggesting the dendritic growth layer will
deepen overnight, resulting in higher snow-to-liquid ratios
despite the somewhat meager liquid-equivalent moisture expected
with the main shortwave trough overnight. Some forecast
soundings show an archetype favorable for snow-to-liquid ratios
exceeding 20:1 by late tonight, which would favor low-density
but notable snowfall accumulations of a few additional inches.
We will continue to monitor that, but no significant changes
were made to the snow forecast with this update cycle. Changes
that were made include increasing precipitation (snowfall)
chances to 80-100% most of the night in much of western and
south central ND, and to add Burleigh and Logan Counties into
the existing Winter Weather Advisory. While there is not much
change to the previous snow forecast, observed travel impacts in
these counties are not too dissimilar than areas already in the
advisory, and persistence of the aforementioned banding
structure in parts of those two counties also favored adding
them into the advisory. In general, we still expect additional
accumulations in the advisory area to be in the 1 to 3 inch
range overnight, but with low to medium chances of locally
seeing up to 4 additional inches of snow.

&&

.DISCUSSION...
Issued at 226 PM CST Fri Nov 28 2025

The upper level pattern over North America currently consists
of ridging over the west coast, west-northwest flow over much of
the central region and a couple stronger embedded shortwave
troughs moving down the backside of that ridge, approaching the
Northern Plains tonight. The associated surface low was located
approximately over eastern Wyoming and Colorado resulting in a
generally east/southeast surface flow over ND. Warm air
advection/isentropic lift with some pronounced frontogenesis in
the 850-700mb layer earlier today supported a band of snowfall
over our southwest and south central counties with lighter snow
elsewhere. Model QPF has seemed a little high, probably more
noticeable with high SLRs, giving model total snow forecasts a
boost. So far the highest totals we have received have been
around 3". Surface obs, radar, DOT road condition reports and
plow webcams as well as NDAWN webcams support maintaining the
advisory as is. Locally Bismarck total snow forecast creeps into
advisory range, but with amounts over the remainder of the
county forecast to be less and based on upstream trends, will
not extend the advisory at this time. As mentioned in previous
discussions, soundings continue to show decent lift in the DGZ
this evening as temperatures through the profile drop. So
despite the relatively low QPF forecasts, it would not take much
to boost snow totals.

Otherwise, as synoptic scale lift depicted by Q-vector convergence
exits to our south late this afternoon, the upstream trough will
cross our area overnight, supplying another area of lift that will
support continued mostly light snow over much of our region.
Generally, looking at 1 to 4" of snow accumulation during the
overnight period, before the trough passes to our south and snow
ends on Saturday.

High pressure then builds in from the west later on Saturday into
Sunday, with dry and cold weather expected. Upper level flow will be
mostly northwest with some transient troughs and ridges resulting in
temperature fluctuations during the week. Sunday highs will be in
single digits above zero to the low teens southwest, with overnight
lows Saturday night and Sunday night dropping to the single digits
below zero. Temperatures moderate quickly by Tuesday before dropping
again just as quickly on Wednesday. NBM probabilities show higher
uncertainty by around Tue/Wed. Along with this pattern there are
periodic low chances for snow. However, at this time there are
no indications of any significant storms next week.

&&

.AVIATION /06Z TAFS THROUGH 06Z SUNDAY/...
Issued at 114 AM CST Sat Nov 29 2025

MVFR to IFR conditions in snow are expected to continue overnight
across most of western and central ND, with visibility generally
in the 1-3SM range in snow. Snow will gradually end from west to
east late tonight and Saturday, ending in western ND from 09 to 15
UTC, and in central ND between 15 and 21 UTC. In the wake of the
snow, MVFR ceilings are expected to persist Saturday an into
Saturday night at most terminals. East winds at 10-15 kt tonight
will gradually turn to the north-northwest on Saturday at similar
speeds.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory until 6 AM CST /5 AM MST/ early this
morning for NDZ017>020-031>035-040>047-050-051.

&&

$$

UPDATE...NH
DISCUSSION...JNS
AVIATION...CJS/NH