351
FXUS63 KBIS 121511
AFDBIS

Area Forecast Discussion
National Weather Service Bismarck ND
911 AM CST Wed Feb 12 2025

.KEY MESSAGES...

- Life-threatening wind chills will continue statewide through
  Thursday morning.

- After a slight warmup in temperatures for Thursday, very cold
  temperatures and wind chills will return Valentine`s Day
  through the weekend.

- There are periodic low chances for light snow Friday through
  Monday.

&&

.UPDATE...
Issued at 910 AM CST Wed Feb 12 2025

No major changes were needed for this update as a frigid morning
continues across western and central North Dakota. Just updated
cloud cover for the next few hours and blended in the latest
observations to the going forecast.

UPDATE
Issued at 605 AM CST Wed Feb 12 2025

Stratus continues to expand across the forecast area, and is a
bit lower than forecast, with flurries intermittently observed
underneath the cloud deck. Did expand and extend mention of
flurries into the early afternoon, with some question on how
long stratus will persist. Also added in mention of patchy fog
across the far northwest for the next few hours, with very low
clouds and reduced visibility reported at Crosby. Headlines
continue as planned, with scattered pockets of wind chills down
to -40 to -45 across the entire forecast area.

&&

.DISCUSSION...
Issued at 312 AM CST Wed Feb 12 2025

Dangerously cold temperatures and wind chills continue this
morning as the forecast area is placed in between Arctic highs
at the surface, and cyclonic flow aloft from a Hudson Bay low. A
surface trough traversing the forecast area is bringing a
smattering of low clouds, with occasional flurries observed
underneath the cloud deck. Temperatures are rising slightly when
the clouds move in but with a shift to northwest winds at 10 to
15 mph, wind chills are still anywhere from -30 to -45 F,
especially with temperatures dropping again after the clouds
move out. To the south and east, where clouds have not yet
reached, air temperatures tonight have been -20 to -30 F.

Partly cloudy and very cold conditions continue today, with
highs staying at or below zero for the entire forecast area as
the Arctic high to our west drifts into the state. We again
dropped forecast low temperatures tonight into Thursday
morning, with high confidence in the surface high tracking right
through the state and into southeast North Dakota late in the
overnight period. Local research shows that this pattern favors lows
falling to the NBM 25th percentile or lower, and the relatively
fresh snowpack, along with lows overachieving the past few nights,
gives increased confidence in that outcome. This puts forecast
lows from -25 to -30 F in the north central through the James
River Valley, and -20 to -25 F across the rest of the forecast
area. No changes were needed to current headlines with this
update. We have an Extreme Cold Warning across all of western
and central North Dakota through this morning, with that warning
continuing for counties north and east of the Missouri River
through Thursday morning, while areas to the west switch to a
Cold Weather Advisory through that period.

We get a brief reprieve from the extreme cold during the day
Thursday as shallow ridging and a warm front move through. The
entire forecast area is forecast to warm above zero, with single
digit highs across the north and east, while the southwest will
warm into the lower 20s. Wind chills Thursday night will be
close to criteria for a Cold Weather Advisory, but we`ll see if
we can get a break from headlines for one day.

The relative warmup will not last long, however, as another push of
Arctic air drops south for the weekend, while quasi-zonal flow aloft
brings multiple weak impulses moving through the region, leading to
the return of snow chances. The first is Friday, with a 20 to 30
percent chance of light snow across the south central and southeast,
followed quickly by 20 to 40 percent chances Friday night through
Saturday across the west and south central. Accumulations with both
of these waves look very light overall, under an inch, with the
exception of the wave on Friday when southeast North Dakota has a
medium probability for at least one inch of snow. The Friday system
has moved north from previous forecasts, and has a decent swath of
warm air advection and some moderate frontogenesis in deterministic
guidance, so worth watching to see how this trends over the next few
days.

Highs on Friday will range from around zero north to the lower teens
south, with air temperatures Friday night into Saturday dropping
to -10 to -15 F for most of the area, producing wind chills in
the -25 to -30 range. We then trend colder for the remainder of
the weekend and into the start of next week, although some
uncertainty in how cold we get Sunday night into Monday with
increasing spread in NBM temperature percentiles. Regardless,
highs on Saturday and Sunday will likely be in the single digits
above and below zero, with overnight lows of -15 to -25 F and
subsequent wind chills in the -35 to -40 range across the north
and east. We would expect to have cold headlines return for
these areas this weekend.

Another round of snow chances return Sunday night into Monday, with
low chances for over an inch of new snow for areas south and west of
the Missouri River. Highs will likely stay in the single digit
range both Monday and Tuesday, before cluster analysis begins to
show hints of a more robust synoptic pattern change that favors
more prominent ridging out west, leading to a warming trend
late in the work week.

&&

.AVIATION /12Z TAFS THROUGH 12Z THURSDAY/...
Issued at 605 AM CST Wed Feb 12 2025

Widespread low stratus continues to expand across the forecast
area, with ceiling heights ranging from 1500 to 6000 feet, with
no real consistency in where the lowest ceilings are occurring.
Additionally, there are some IFR/LIFR pockets in northwest North
Dakota, potentially impacting KXWA although not confident in
ceilings being consistently this low if they occur. The
expectation for now is that clouds will slowly diminish through
the day and return all terminals to VFR. There are some hints
that lower ceilings will move into north central North Dakota
late in the period but did not include anything below VFR at
that point with this update. Northwest winds start the period
before becoming light and variable tonight as a surface high
moves through, then shifting to southerly at the end of the
period.

&&

.BIS WATCHES/WARNINGS/ADVISORIES...
Extreme Cold Warning until noon CST Thursday for NDZ001>005-
009>013-021>023-025-035>037-046>048-050-051.
Extreme Cold Warning until noon CST /11 AM MST/ today for
NDZ017>020-031>034-040>045.
Cold Weather Advisory until noon CST /11 AM MST/ Thursday for
NDZ017>020-031>034-040>045.

&&

$$

UPDATE...ZH
DISCUSSION...Jones
AVIATION...Jones