Garrison, North Dakota 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

347
FXUS63 KBIS 240923
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
323 AM CST Wed Dec 24 2025

.KEY MESSAGES...

- Patchy fog may linger through the morning. Fog may return
  again this evening through Christmas morning.

- A large temperature gradient remains across the area with
  highs through Friday generally near to below average north and
  east of the Missouri River (teens and 20s) to above average
  south and west of the river (30s and 40s).

- 20 to 30 percent chance of light mixed precipitation on
  Christmas Day, mainly north and east.

&&

.DISCUSSION...
Issued at 323 AM CST Wed Dec 24 2025

There are two main forecast challenges for today through
Christmas night. The first is the potential for widespread dense
fog. The second is for light mixed precipitation on Christmas
Day. The bottom lines up front to the next few paragraphs of
this discussion are that no major winter weather systems are
expected for the Christmas holiday. However, there is a greater
than zero chance of at least some impactful weather at times.

In regard to fog, various locations are currently reporting
reduced visibility, though still mostly in excess of 5 SM.
Overall, hi-res models have greatly backed off on dense fog for
this morning and today compared to yesterday. This isn`t too
surprising as the set-up didn`t seem overly favorable. For one,
near-surface winds are progged to remain in excess of 20 kts
through most of the early morning, though perhaps weakening
towards mid-morning. Second, cloud cover is present across most
of the state. Third, despite southeasterly flow across parts of
the area early this morning, winds are shifting to a more
northerly (and unfavorable) direction. Finally, despite moisture
advection in the lower levels, there hasn`t been any impactful
snowmelt to help saturate the surface layer. In areas where
temperatures reached the mid 30s to low 40s yesterday, there is
no snow. In areas where snow is present, temperatures didn`t get
above freezing.

In regard to tonight through Christmas day, some hi-res models
remain quite aggressive in fog development. However, there
remain inhibitors here as well. First, models are a bit slower
in high pressure propagating across southern Canada than they
had been. This meaning that southeasterly flow at the surface
isn`t progged to return until later tonight for much of the
area. But even when it does, sustained winds are mostly around
10 to 15 kts with gusts up to 20 kts. Without significant
snowpack melting, such as you`d expect more in the springtime,
these winds seem a little strong to produce widespread advection
fog, even with saturation in the lower levels. Furthermore,
once again, near-surface winds remain elevated and generally in
excess of 20 kts with directional shear. All of this favors
low-level stratus, perhaps with areas of 3 to 5 SM visibility
reductions from fog, over widespread dense fog. However, both
outcomes are plausible depending on the atmospheric reality when
all is said and done.

Of note, as mentioned, there is a lot of low level moisture
available off the surface. Deterministic forecast soundings
favor a saturated layer that approaches, but generally remains
just under 1 km in depth. These soundings also suggest
saturation may approach the DGZ, especially along and east of
the Missouri River, and in the north. As such, should any
precipitation be squeezed out of a theoretical low-level stratus
deck, the exact p-type remains in question. It could wind up in
the form of light freezing drizzle, light snow/flurries, or
sleet. Perhaps periods of a true wintry mix as well. Of note,
NBM Pops have really pulled back in regard to Christmas day with
most mentionable PoPs now in the evening for the eastern half
of the state, and mostly non-mentionable PoPs during the day in
all but the southwest. Though 20 percent pockets remain in the
north. Of note, even if any freezing rain or drizzle does occur
ice accumulation probabilities are low with the NBM maintaining
10 to 20 percent chance of .01 inch over a 24 hour period
(closer to 10 percent for any six hour period) and the HREF FRAM
ensemble mean only producing very isolated pockets of .01 inch
of ice accumulation.

Beyond the holiday, shortwave energy could bring light
precipitation mainly to northern North Dakota to finish out the
week. As of now, this is favored to mostly be in the form of
snow. After which, mostly dry conditions are favored for Sunday
and Monday with low chances returning during the middle of next
week.

In regard to temperatures, the pattern of cooler temperatures
northeast to warmer temperatures southwest is favored to
continue through the remainder of the week. The exception is
Saturday where the gradient may be more north to south. Very
cold temperatures are progged to return on Sunday with highs
mostly in the single digits on either side of zero, except a
bit warmer and in the low teens southwest. Combined with windy
conditions, cold weather headlines may wind up being necessary
when all is said and done. Of note, models really have no idea
of what is going to happen next week. For example, there is an
insane NBM ensemble 25th/75th temperature spread on New Year`s
Eve. Currently it is a 40 degree spread for high temperatures in
Bismarck from 5 below zero to 35 above zero. In other words, be
on the lookout for the possibility of a large change in the
deterministic forecast beyond Sunday, and especially on New
Year`s Eve.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1004 PM CST Tue Dec 23 2025

Mostly VFR conditions to begin the 06Z TAF period. although
there is some patchy fog around KDIK.

We anticipate an increase in low level moisture through the TAF
period with low stratus/fog eventually developing across much of
western and central North Dakota. With the 00Z TAFs we
mentioned CAMS backing off on the areal extent and pushing back
the arrival of stratus/fog. That trend continues with the 06Z
TAFS. Although there is some stratus/fog depicted overnight, its
areal extent is much less (mainly northwest and JRV). Although
its hard to tell with the widespread high clouds, at this time
there is little in the way of low clouds across ND, so other
than some patchy MVFR vsbys, widespread fog looks to hold off
until late tonight or even later, possibly not even until
Wednesday night. By late in the TAF period it does look there is
much more agreement in widespread stratus/fog developing. Will
definitely be pushing back and lowering expectations for fog
overnight into tomorrow morning. Winds start out southerly to
begin the TAF period, and turn northerly by mid morning
Wednesday, then veering to the east/southeast by the end of the
TAF period, and becoming a little breezy from the southeast
after 00Z Thursday.

&&

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

&&

$$

DISCUSSION...Telken
AVIATION...TWH