064
FXUS63 KBIS 161725
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1125 AM CST Sun Nov 16 2025

.KEY MESSAGES...

- Areas of dense fog over far northwestern North Dakota through
  early this afternoon.

- Near to slightly above average temperatures expected this
  week, with highs each day around 35 to 50.

- Low to medium chances for light precipitation, mostly falling
  as rain, Monday afternoon through Monday night and Wednesday
  evening through Thursday morning.

&&

.UPDATE...
Issued at 1117 AM CST Sun Nov 16 2025

Dense fog over much of Williams and McKenzie Counties has been
very reluctant to dissipate, while other areas have seen
notable improvement. Therefore, have decided to continue a Dense
Fog Advisory until 1PM CST. Otherwise, other main change was to
cloud cover. Broad area of lower cloud cover from north central
North Dakota through the James River Valley overall has been
pushing east, but redevelopment has been occurring along its
backside. In the meantime, higher clouds continue to stream
through western North Dakota into the south central. Therefore,
have done an notable increase to cloud cover through the day.

UPDATE
Issued at 739 AM CST Sun Nov 16 2025

Dense fog continues to spread slowly northward, so have added
Williams County to the ongoing Dense Fog Advisory. Otherwise, no
additional changes needed at this time.

UPDATE
Issued at 551 AM CST Sun Nov 16 2025

A Dense Fog Advisory has been issued for west central and
southwest North Dakota until 10 AM MST. Both satellite and
webcam imagery show dense fog expanding across the area, and no
improvement is expected until at least an hour after sunrise.

&&

.DISCUSSION...
Issued at 349 AM CST Sun Nov 16 2025

Northwest flow aloft over the Northern Plains early this
morning, with a downstream negative-tilt trough cutting through
Ontario and a negative-tilt upstream ridge from the Northern
Rockies to Texas. An oblong surface high pressure is analyzed
from north central North Dakota to northeast South Dakota. A
band of stratus clouds has persisted along the western periphery
of the surface high from northwest to south central North
Dakota, drifting ever so slightly eastward through the night. A
narrow strip of radar reflectivity has been present underneath
the stratus for several hours, but there is no recent
confirmation of anything reaching the ground. To the west of the
stratus, areas of dense fog are developing across far western
North Dakota, mainly along and west of a line from Watford City
to Hettinger. At the time of this writing, the fog had not yet
become widespread enough to warrant an advisory, but models do
indicate a greater coverage of the fog closer to sunrise.

Aside from the fog, an uneventful weather day is anticipated.
The surface high is forecast to shift over Minnesota and Iowa,
with the upper ridge axis shifting east of the Northern Rockies
by the end of the day. RAP low level RH fields suggests the low
clouds may persist and gain eastward momentum this morning, and
some higher clouds could move in from the west by the end of the
day. The high temperature forecast for this afternoon ranges
from around 40 in the Turtle Mountains area to the lower 50s in
the southwest corner of the state. The upper ridge axis is
forecast to reach the Dakotas tonight as a strong southern
California low lifts into the Great Basin/Central Rockies. A
partly to mostly cloudy night is anticipated, with lows in the
mid 20s to mid 30s.

The upper low is forecast to eject into Nebraska on Monday,
cutting through the upper ridge axis. Latest model guidance has
consolidated on a more southern track within the previous
envelope of solutions, which would favor a drier outcome for
North Dakota. Nevertheless, there could still be enough warm air
and moisture advection wrapping around the northeast quadrant
of the low combined with deformation related lift to bring some
light precipitation into the state Monday afternoon through
Monday night, with relatively higher chances south compared to
north. A broad easterly surface flow could also contribute
orographic ascent that could result in a deep saturated near-
surface layer. Model soundings, both deterministic and ensemble
based, project an isothermal layer at or just barely above
freezing. Therefore, if saturation of the near-surface layer
does occur, any precipitation reaching the surface would likely
fall in the form of drizzle, with surface temperatures forecast
right around freezing. The probability of impactful freezing
drizzle Monday night remains low, but it is still the most
probable hazardous weather phenomenon (aside from fog) in the
forecast this coming week. NBM probabilities do maintain snow as
a possible precipitation type in some areas Monday night. There
is enough ensemble spread in the lower thermal profile to keep
the mention of snow, but we did not allow snow to be mentioned
on its own as the only singular forecast type of precipitation
(i.e., either liquid or a mix).

The latest NBM has lowered PoPs below 15 percent on Tuesday,
and this fits with ensemble guidance now favoring a transitory
ridge over the region. It is now not until Wednesday evening
that a 20 to 30 percent chance of precipitation returns to the
forecast as the northern stream of a split flow trough crosses
the state. But even these probabilities have decreased from
previous forecasts as there is increasing uncertainty in the
evolution of the base of the trough to close out the week.
Ensemble clusters are unified in a broad and benign northwest
or zonal flow pattern locally heading into next weekend, but
deterministic models portray nearby chaos in their
height/vorticity fields.

It should be noted that prior to the arrival of the northern
stream trough late Wednesday, there will be a period of
southwest flow aloft, and it is possible that global models/
ensembles are not resolving weak impulses that could bring light
precipitation across the state late Tuesday into Wednesday. The
temperature forecast at both the surface and through the lower
levels of the atmosphere continues to trend warmer through next
week, but there is still a larger spread in the NBM maximum
temperature distribution, and the deterministic forecast remains
skewed toward the warmer end. Any day this coming week that
features more clouds than sun could easily see high temperatures
a few, if not several degrees cooler than what is currently
projected. Having said all that, there is still a noticeable
shift warmer from previous forecast iterations. In fact, our
precipitation forecast for the Wednesday evening through early
Thursday morning time period is now almost entirely and
exclusively rain, with a wintry mix just across the far north.

&&

.AVIATION /18Z TAFS THROUGH 18Z MONDAY/...
Issued at 1117 AM CST Sun Nov 16 2025

Over far northwest North Dakota including the KXWA terminal,
dense fog producing LIFR ceilings and visibility has been
reluctant to dissipate, thus expect it to linger into the early
afternoon, with improvement after 19Z. Conditions will then
gradually improve becoming VFR by late afternoon. Further east
over north central North Dakota into south central and parts of
southeast North Dakota, lower clouds will linger through much of
the afternoon, but overall look to hold just above MVFR levels,
though localized spots of MVFR ceilings remain possible. Most
locations are expected to be VFR tonight.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 1 PM CST /noon MST/ this afternoon
for NDZ009-017.

&&

$$

UPDATE...JJS
DISCUSSION...Hollan
AVIATION...JJS