579
FXUS63 KBIS 270530
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
1130 PM CST Wed Nov 26 2025

.KEY MESSAGES...

- Widespread dense fog is possible across much of western and
  central North Dakota overnight through Thanksgiving morning.

- There are medium to high chances (60-80 percent) for
  accumulating snowfall (up to 4 inches) Friday and Friday
  night across portions of western and south central North
  Dakota.

- Well below average temperatures are favored for this coming
  weekend and 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 1130 PM CST Wed Nov 26 2025

Areas of fog continue across much of northwestern and central
North Dakota at the time of this early night update, with more
patchy fog found in the southwest. Fog is expected to continue
to expand to the southwest through the early morning, though
will have to contend with some high clouds moving into the far
southwest at this time. No major adjustments to the forecast
were performed with this update, as it remains broadly on track.

UPDATE
Issued at 849 PM CST Wed Nov 26 2025

Fog continues to expand southwestward, thus the Dense Fog
Advisory has been expanded a few counties to the south and west.
There are some visibility improvements for areas that were
previously in dense fog this afternoon, because the low stratus
convergence zone has moved southwestward. However visibility
reductions are still being reported across much of south
central, north central, and northwest North Dakota. Dense fog
will likely persist across the region tonight through early
tomorrow morning. There have also been some flurries being
observed across the eastern side of the county warning area.
Updated the grids to reflect the current observations.

UPDATE
Issued at 532 PM CST Wed Nov 26 2025

After sunset, the visibility have tanked across the state as
temperature near the dew point over the fresh snow pack. The
convergence zone of the low stratus deck stretching from eastern
Divide down to northern Burleigh counties has had multiple
observations and webcams showing visibility 1/4 mile or less.
Thus, prompting a Dense Fog Advisory for much of northwest,
north central, and south central North Dakota through
Thanksgiving morning. Fog is forecast to expand to the southwest
which will cause the advisory to likely grow in the next few
hours. Will continue to monitor the fog`s progression and
increase the advisories area when warranted.

&&

.DISCUSSION...
Issued at 240 PM CST Wed Nov 26 2025

Currently the low stratus clouds in the north central are still
hanging on, and will become more widespread through the night.
Aloft, the upper level flow is strong from the northwest as the
low pressure system became a closed low over Wisconsin today.
In the Pacific Northwest a ridge is moving on shore. At the
surface an area of lower pressure sits in Montana, with a
slightly higher pressure center over South Dakota.

Tonight, as mentioned, widespread dense fog is very possible.
Winds will remain calm overnight, letting the moisture from the
fresh snow just sit in the air. This, with the temperatures
cooling, will saturate the air fully. The CAMs are in agreement
that western and south central ND is the most confident
location for the fog. We added fog to almost the rest of central
ND where the snow fell yesterday. The timing is around sunset
to about noon MST(as of now). A Dense Fog Advisory is very
likely, we will just wait for now until it starts to form.

The rest of this week will be below average temperatures under
the northwest flow. Thursday a low pressure system moves off the
Pacific Ocean into Washington state. It then looks to combine
with a shortwave moving down from Canada over Idaho and western
Montana. This is then when models differ. Some have this
shortwave deepening only a little and others down into Kansas.
Either way a surface low pressure system will impact the Northern
Plains and produce snow Friday to Saturday morning. The heaviest
snowfall is likely Friday afternoon and evening. Confidence
continues to increase for this and probabilities for higher
amounts are increasing. We now have a medium chance (40 to 60%)
of 4 inches of snow in the west and south central now. With a
low chance (20 to 40%) of 6 inches. This event, unlike the last,
seems more frontal driven. Except it will form on the upper
level front where the frontogenesis seems stronger than at the
surface front. The jet stream will wrap around the upper low and
create a max area over southern ND. Where the jet stream max
and the upper front line up, at least 4 inches of snow is very
possible. The cutoff for the higher amounts is basically the
river in the northwest, over to southern Ward County and down
through Kidder County. Areas north and east of that line will
likely see 1 to 2 inches as of now. One possible limiting factor
is the lapse rates are only around 6 C/km. Lapse rates dropping
quickly north of that diagonal line.

On the backside of the system, temperatures will cool even more
with cold air wrapping into the low. Highs will be in the teens
Sunday. Sunday and Monday morning lows will be below zero with
wind chills of negative 25 possible. Next week, strong northwest
flow will continue but the ridge axis will be close to North
Dakota so temperatures should be in the 20s. Up stream into
Montana zonal flow could create more chances of snow off the
mountains mid week.

&&

.AVIATION /06Z TAFS THROUGH 06Z FRIDAY/...
Issued at 1130 PM CST Wed Nov 26 2025

Low stratus and fog can be be found across much of western and
central North Dakota at the start of the 06Z TAF period. IFR to
LIFR ceilings and visibility are expected at all terminals
at all terminals through mid to late Thursday morning, with
conditions beginning to improve by the early afternoon. Another
round of low stratus and fog will be possible across western and
portions of central North Dakota late Thursday evening through
the end of the TAF period, though confidence remains too low to
include at any given terminal with this update. Otherwise, light
north to northwest winds tonight through Thursday morning will
start to turn south southeasterly Thursday afternoon and evening.


&&

.BIS WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 10 AM CST /9 AM MST/ Thursday for
NDZ001>003-009>011-017>022-034>036-046-047-050.

&&

$$

UPDATE...Adam/Johnson
DISCUSSION...Smith
AVIATION...Adam