522
FXUS63 KABR 021544 AAB
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
944 AM CST Tue Dec 2 2025

.KEY MESSAGES...

- Downslope winds are expected today on and east of the lee of the
  Prairie Coteau in northeast South Dakota. Visibility could be
  reduced to one half mile at times.

- A quick moving disturbance will push through the region today
  into early Wednesday, kicking off a 30-50% chance of light snow
  over north central and northeast South Dakota and a wintry mix
  of mainly rain/snow across central South Dakota.

- Very cold air across the region Wednesday and Wednesday night,
  with lows in the single digits below and teens below zero. Wind
  chills may reach 15 below to 25 below zero in the James River
  valley.

- Snow chances (20-35%) return Friday/Saturday as more clipper
  systems potentially move through the region.

&&

.UPDATE...
Issued at 935 AM CST Tue Dec 2 2025

The above freezing surface air temperature is along/west of the
western CWA border west river. KPHP is 31F degrees. Fort Pierre
RAWS is 27F degrees. Pierre ASOS is 19F degrees. Above freezing
temperatures are showing up from Dickinson/Hettinger up in North
Dakota down to Buffalo/Faith/Rapid City in South Dakota, and this
warm air is expected to advect eastward today on 20 to
30-something knot 0.5km/mixing layer winds. But, right now, all
these returns on radar across central/north central South Dakota
are just virga returns as the atmosphere works to saturate things
down close enough to the ground for precipitation to reach all the
way to the ground before evaporating/sublimating. RAP soundings
suggest Mobridge/Pierre could be saturated enough to produce
precipitation reaching the ground at or after noon CST. P-type
still looks predominantly either snow changing to rain or just
rain across central South Dakota this afternoon, eventually
transitioning back to snow this evening. There is a corridor,
though, from appx Gettysburg to Huron where P-type could be rather
a mess of snow/rain or freezing rain just depending on what the
surface temperature ultimately ends up being from mid-afternoon
through early this evening before P-type returns to just all snow
later this evening.

UPDATE Issued at 542 AM CST Tue Dec 2 2025

The aviation discussion has been updated for the 12Z TAFS.

&&

.SHORT TERM /TODAY THROUGH WEDNESDAY AFTERNOON/...
Issued at 504 AM CST Tue Dec 2 2025

Relatively quiet but cold conditions persist for most locations.
Temperatures vary widely with subzero readings mainly across parts
of northeast SD with single digits above zero elsewhere such as
central SD. Skies remain clear for the time being in our east
while high clouds are starting to thicken across the western
Dakotas. Favorable wind direction across the Missouri Valley is
producing another round of low stratus downwind of Lake Oahe and
Lake Sharpe. Within some of these areas, dense fog has led to low
visibility at times in the Pierre and Mobridge areas. Hi-res
guidance had pointed to expansion of some of this fog eastward
toward the James Valley through the early morning hours, but has
sense backed off. This will be a trend we`ll have to keep an eye
on through daybreak.

For today, clouds will be thickening out ahead of a warm front that
is progged to shift west to east across the forecast area. Low level
WAA pattern will develop and try and scour out the arctic air that`s
been in place. This will be most successful across our western zones
where temperatures will reach the low to mid 30s. Sub-freezing temps
are anticipated across our east. Southwest flow across the Prairie
Coteau will lead to another round of gusty winds in the downslope
areas by mid to late morning through at least mid afternoon. There
could be localized blowing snow effects in that area. Clouds will
continue to thicken in the low to mid levels by midday into the
afternoon. Low pressure is progged to track southeastward across
eastern ND into west central MN this afternoon. Light precipitation
in the form or mostly light snow will be possible across northeast
SD and west central MN where BUFKIT profiles suggest the temperature
profile through the saturated column remains subfreezing. However,
farther west across central SD, some of that warm air will win out
allowing for the potential for a rain/snow mix or just plain rain
for a period of time this afternoon. As the low levels begin to cool
late in the day, a period of a wintry mix or freezing rain will be
possible. Guidance continues to suggest QPF will be rather limited
through the entirety of this event, so anticipate minimal impacts
from a light coating of snow or light glaze in areas that see
freezing precip.

That area of low pressure will continue southeast and drag a strong
cold front through the forecast area this evening. Winds increase of
the north and northwest. Any leftover moisture will accompany the
fropa with the potential to see a few more snow showers or flurries
into the overnight hours. A CAA pattern sets in overnight with the
leading edge of a much colder air mass sinking southward into our
area early Wednesday. That pattern is expected to persist through
most of the day on Wednesday. Temperatures are likely to be warmest
early in the morning on Wednesday and then we should see falling
temperatures through the morning and midday hours. Temps may
stabilize for a brief time the first half of the afternoon, but
anticipate readings will start to plummet by the late afternoon
areas. Winds will be strongest during the morning and early
afternoon hours leading to wind chill values between 5 and 15 below.

&&

.LONG TERM /WEDNESDAY EVENING THROUGH MONDAY/...
Issued at 504 AM CST Tue Dec 2 2025

Surface high pressure centered over the region at 00Z Thursday will
shift southeast into IA by 12Z Thursday. Southerly winds increase
between 06Z and 12Z Thursday with warm air advection developing as
well. Therefore, it appears lows Wednesday night may be closer to
06Z, with steady/rising temperatures up through 12Z. Apparent T
grids still show wind chills from 25 below to 30 below zero in the
James River valley Wednesday night.

GEPS/GEFS/ENS 500mb heights are in good agreement in the mid/upper
level pattern featuring a persistent northwest flow aloft during the
rest of the extended period. There are a couple waves that moves
southeast across the region during this time, but with low
confidence on timing and precip chances/placement. Right now, the
highlight is on Friday night into Saturday with the highest chances
(20-30%) in the forecast. GEFS/GEPS/ENS all show some light QPF over
the region as a wave of low pressure slides to our south and we
potentially receive light snowfall accumulations across the CWA.
Precip chances may eventually increase over the coming day or two.

Temperatures are a bit uncertain as well as the Northern Plains see
a battle of air masses, with swings of relative mild air (20s/30s)
and colder arctic air with periods of lows in the single digits
above and below zero. Inherited max/min temp forecasts reflect this,
while low confidence remains on the actual numbers as shown in
larger spreads of the 25th/75th values in the NBM.

&&

.AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/...
Issued at 542 AM CST Tue Dec 2 2025

Terminals KABR,KATY,KPIR,KMBG

LIFR conditions will persist at KPIR as a result of locally dense
fog leading to vsbys down to 1/4SM and VV001. These conditions are
likely to prevail through sunrise until about 13-15Z as higher
clouds thicken and winds some around to a southwest to west
direction. Otherwise, expecting VFR conditions to return at KPIR
and prevail for KABR/KATY/KMBG into the afternoon hours. Low level
clouds thicken and conditions will be back to MVFR cigs later this
afternoon and evening. A disturbance moving through the region
will generate light snow for terminals in the east like KATY and a
rain/snow mix or a freezing rain/snow mix this afternoon and
evening at KPIR. MVFR vsbys will be possible at these terminals
due to the precip. Light to moderate south to west winds expected
through today before turning more northwest late in this TAF cycle
and increasing with gusts up to 20-25 knots.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...None.
MN...None.
&&

$$

UPDATE...10
SHORT TERM...Vipond
LONG TERM...TMT
AVIATION...Vipond