Beulah, North Dakota 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

397
FXUS63 KBIS 221245
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
645 AM CST Mon Dec 22 2025

.KEY MESSAGES...

- There is a 20 to 30 percent chance of light freezing rain
  north of Interstate 94 this morning and afternoon. Little to
  no impacts are expected.

- High temperatures through the upcoming week are favored to
  range from 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).

- Low to medium chances (20 to 40 percent) for light mixed
  precipitation on Christmas Day.

&&

.UPDATE...
Issued at 645 AM CST Mon Dec 22 2025

Mid to high clouds continue to stream over the state this
morning. But despite the satellite analysis of multiple thick
layers of clouds, the 12Z KBIS RAOB shows little to no
saturation, even with respect to ice. Particularly dry is the
sub-cloud layer below 700 mb, or approximately 10,000 ft AGL.
This confirms the forecast trend towards a drier solution for
today. HRRR/RAP runs have remained consistently dry over almost
the entire state, until the 11Z RAP arrived with a larger area
of light freezing rain entering western North Dakota by sunrise
and then vanishing by midday. This precipitation can be traced
back to central Montana, where there were several rain
observations at the top of the last hour. But the areal extent
of observed rain is not nearly as far east as the RAP has it
this hour, and a comparison of the RAP sounding at Bismarck to
our observed sounding shows the RAP to be overly-saturated. All
this is to say that we don`t buy into the 11Z RAP solution of a
widespread freezing rain event unfolding in the next couple
hours. But since it is a viable solution from a viable NWP
model, the probability of occurrence is not zero.


&&

.DISCUSSION...
Issued at 502 AM CST Mon Dec 22 2025

Early morning upper height analysis shows broad ridging over
the Northern High Plains/Canadian prairie provinces. RAP
analysis shows an underlying 700 mb shortwave over the Dakotas
with poleward warm air advection underneath the shortwave. Mid
to high clouds are prevalent this morning, but a very dry layer
of air above the surface, which was measured to be as high as
500 mb on the 00Z Aberdeen RAOB last evening, is preventing any
precipitation from reaching the ground. While the top of the dry
layer has saturated to some extent overnight, we can assume
very low RH from above the near- surface inversion layer to
observed cloud ceilings, which are mostly around 7,000 to 10,000
ft. This dry air will play a key role in how much
precipitation, if any, the northern two thirds of the state will
receive from a shortwave ejecting off the Canadian Rockies this
morning, traveling along the international border through this
afternoon. Latest ensemble guidance has shifted this wave
slightly farther north and lowered probabilities for measurable
precipitation, drastically so outside of the northern tier of
counties. On the whole, this leads to a much lower chance of
impactful winter weather for a majority of our forecast area
today. But the caveat is that the northward shift increases
conditional probabilities for precipitation falling as freezing
rain (or just rain where above freezing - mainly south and west
of the Missouri River this afternoon), and snow and sleet now
appear to be plausible types only along the Canadian border
where there are still near equal conditional probabilities for
freezing rain. We will continue to carry a 15 to 20 percent
chance as far south as the Interstate and leave just a 30
percent chance along the Canadian border, as 06Z CAMs appear to
be trending even drier. Overall, there are two main areas of
weak forcing that could produce light precipitation today. One
is a west-east zone of mid level frontogenesis that has
latitudinal placement uncertainty but generally favored between
Highway 200 and Interstate 94. The other is closer to the
shortwave moving along the Canadian border where modest Q-vector
convergence is forecast. But once again, it would be a
reasonable outcome for the entire state to remain dry today on
account of the very dry air in the lower levels.

A cold front attendant to the surface low initiated by the
shortwave is forecast to cross the state late this afternoon and
evening. Deterministic and ensemble guidance have backed off on
the magnitudes of mean mixing layer winds, cold air advection,
and pressure rises. We could still see some gusty winds this
afternoon and evening, moreso across the north where cold air
advection and pressure rises are forecast to be stronger. But
very poor low level lapse rates and post frontal mixing heights
only around 1,000 ft AGL should greatly inhibit strong momentum
transfer. Lows tonight are forecast to fall below zero north of
Highway 2, while remaining in the teens above along and south of
the Interstate. The colder air mass will hang around on
Tuesday, except of course in the southwest corner of the state
where highs could approach 40. Elsewhere, expecting teens
northeast to 30s southwest for highs on Tuesday.

By Tuesday afternoon, deterministic guidance is showing mid
level frontogenesis/isentropic ascent and low level warm air
advection strengthening underneath a broad but weak area of
Q-vector convergence, originating in west central North Dakota
and lifting northeastward. Mainly just the HRRR and RAP are
simulating precipitation with this feature, but mostly falling
as light freezing rain. A sample HRRR sounding does show some
drier air aloft, but not nearly as stout nor as deep as today.
We remain skeptical of this potential given simultaneous mid
level height rise tendencies with broad anticyclonic flow aloft,
but it cannot be completely written off. Will wait to see other
guidance supporting this before adding it to the forecast.

Dry weather is anticipated for Christmas Eve. A building upper
ridge will allow low level temperatures to become anomalously
warm, but a large surface high over Alberta/Saskatchewan is
forecast to direct a cool and dry easterly surface flow into the
state. Southwest North Dakota is still forecast to rise above
freezing, and could reach the 40s. But elsewhere, the NBM
appears to be settling on a cooler outcome compared to what was
being advertised a few days ago, with Christmas Eve highs around
20 to 30 north and east of the Missouri River.

Ensembles are consolidating on southwest flow aloft for
Christmas Day, but with only weak pockets of forcing traveling
over the region. This has resulted in an increase in our
precipitation probabilities to around 20 to 40 percent over much
of the area. Outside of one ensemble cluster that contains half
of the GEFS but no ECMWF or Canadian ensemble members, there is
a zero to 10 percent chance for QPF exceeding one tenth of an
inch on Christmas Day. But yet again, we are looking at another
mixed type scenario. Conditional probabilities for snow are
higher farther north than south, and vice versa for freezing
rain. But the total ensemble probability for above freezing 850
mb temperatures ranges from around 40 percent north to 75
percent south, which explains the large areas of snow, sleet,
and freezing rain that the NBM is projecting for most likely
types, and there is quite a bit of overlap in these types. As
for surface temperatures, the NBM spread has greatly shrunk and
is more focused over a colder outcome than what longer-range
ensemble tools had been hinting at. The median 50 percentile
spread is still around 10 degrees Fahrenheit, but deterministic
output remains skewed toward the colder quartile with highs in
the teens north to 30s southwest.

Longer range ensembles favor southwest flow continuing through
Friday. This could be followed by a much deeper trough over the
weekend, but there are distinct phasing differences among each
ensemble cluster, and mean height/vorticity fields in the
highest membership cluster (around 35 percent membership) barely
show any signal at all for a northern stream trough. One take
away from the cluster analysis over this time period is that a
deeper trough would almost certainly lead to a colder
temperature outcome. But there are only low to medium
probabilities for just 0.01" QPF with all clusters, which could
be indicative of a split flow solution, regardless of phasing.

&&

.AVIATION /12Z TAFS THROUGH 12Z TUESDAY/...
Issued at 645 AM CST Mon Dec 22 2025

VFR conditions are favored at the major terminals for the 12Z
forecast cycle. Early this morning, IFR ceilings will impact
areas north of KMOT. The low ceilings could persist in, or
return to those areas, but would more likely be at MVFR levels
in the afternoon. Then later this evening through tonight, there
are low probabilities for a period of MVFR ceilings behind a
cold front moving through the region. Confidence in this is not
high enough to mention prevailing MVFR in this set of TAFs.
There are also low chances for light freezing rain across mainly
the northern half of the state this morning and afternoon, but
think this will mostly end up being virga. Winds ahead of the
cold front will transition from easterly to southerly around
5-10 kts. The cold front could then bring a period of gusty
west-northwest winds across the state late this afternoon
through this evening. The change in wind direction above the
surface is forecast to be quicker than that at the surface.
This could result in a period of low level wind shear in some
parts of central North Dakota, including at KBIS.

&&

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

&&

$$

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