801
FXUS63 KABR 152331 AAA
AFDABR

Area Forecast Discussion...UPDATED
National Weather Service Aberdeen SD
531 PM CST Mon Dec 15 2025

.KEY MESSAGES...

- Winds of 25 to 35 mph, with locally higher gusts in excess of 45
  mph, will be possible again tonight into Tuesday morning over
  the eastern slopes of the Sisseton Hills.

- Temperatures will remain 10 to 20 degrees above normal Tuesday
  and Wednesday.

- Another arctic blast has the potential to generate 40 to 60 mph
  wind gusts late Wednesday night into Thursday. Snow showers that
  accompany the front could reduce visibilities at times, mainly
  over northeastern South Dakota.

&&

.UPDATE...
Issued at 526 PM CST Mon Dec 15 2025

The forecast remains on track this evening. No major changes are
planned.

&&

.SHORT TERM /THIS EVENING THROUGH TUESDAY NIGHT/...
Issued at 322 PM CST Mon Dec 15 2025

At 3 PM CST, skies are mostly sunny and weak surface high pressure
is over the CWA. There is a wide variety of temperatures and wind
directions throughout the CWA, with temperatures struggling to get
out of the 20s on light and variable winds across far northeast
South Dakota and west central Minnesota, while readings have warmed
up into the 40s to low 50s across central and north central South
Dakota on west winds 5 to 15 mph. Overall, though, all of these
temperatures range from 10 to 25 degrees warmer than this time
yesterday.

Tonight, as this weak surface high pressure system drifts off to the
east-southeast, a surface warm front developing throughout the front
range of the Rockies (northern and central high plains region) will
trek eastward across the Dakotas and Nebraska, signaling a period of
low level WAA overnight. Sensible weather impacts?...there should be
another lee-of-the Prairie Coteau downslope wind event tonight,
persisting into Tuesday. Not an ideal set up, lacking a mean-state-
critical-layer overnight. But, the shear mechanics of low level WAA
and southwest winds at 925hpa/0.5km rolling over the eastern edge of
the Prairie Coteau should generate sustained winds 25 to 35 mph with
some gusts over 45 mph at times throughout that northwest to
southeast corridor along and just east of the lee-slope of the
Prairie Coteau. Overnight low temperatures may end up happening by
late this evening before steadying out or slowly warming through
late tonight/early Tuesday morning.

The low pressure drawing this warm front into the region heading
into Tuesday morning is positioned well off to the north, but its
attendant cold front is progged to push through the CWA by late
Tuesday morning, signaling a switch in the wind to northwesterly.
Models are sending mixed signals regarding just how strong post-cold-
frontal mixing winds might be from late Tuesday morning through late
Tuesday evening. Despite half-kilometer winds ranging between 40 and
55 knots, the strength of the low level CAA is not very much, and
pressure rises/tendencies are only on the order of ~5-7hpa/6-hours.
Also, the momentum transfer tool in BUFKIT for both the GFS/NAM does
not activate during the period of low level CAA. Will toss it back
to the midnight shift for one final evaluation. Right now, if any
part of the CWA would accomplish wind advisory strength winds it
would be McPherson County. After another surface high pressure
system builds down across the region Tuesday afternoon/evening, the
high will drift off to the south/east, and another period of low
level WAA will commence (out west-river) toward the end of the
Tuesday night period. Low temperatures in the teens and 20s for the
next couple of nights are generally 5 to 15 degrees above normal,
while high temperatures largely in the 40s and 50s on Tuesday are,
at least, 15 degrees above normal for mid-December!

&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...
Issued at 322 PM CST Mon Dec 15 2025

A small upper-level ridge is forecast to move over SD Wednesday,
which helps move WAA over the state through the day. This leads to
high temperatures during the day warming up into the upper 30s to
upper 50s, which is 15-25 degrees warmer than normal.

During the day Wednesday, an upper-level shortwave and surface low
pressure starts to move towards SD, with the shortwave reaching the
state Wednesday night around the time the surface pressure has a
frontal passage moving through. Along this frontal passage, the low-
levels have strong CAA pushing in, with an initial line Wednesday
evening and then another surge of CAA later in the night/early
Thursday morning. This strong push of CAA into central and
northeastern SD will help to mix stronger winds aloft to the surface
during Wednesday night into Thursday morning. The EFI/Shift of tails
is highlighting all of central and northeastern SD for strong wind
gusts, with the highest values over north central SD. Model
ensembles have 50-80% chance for wind gusts greater than 40 mph over
central SD Wednesday night (30-60% chance over northeastern SD),
with a 30-50% chance for greater than 50 mph wind gusts over north
central SD.

While winds are a big hazard that could cause problems Wednesday
night into Thursday, these winds combine with other conditions to
potentially create another hazard. Some models are showing a swath
of 10-15 J/kg SBCAPE and steep lapse rates moving in along with the
CAA and stronger winds. Both the NAM/GFS models have a line with the
snow squall parameter reaching values of 1-5 moving through mainly
central SD (west of the James River). While there are hints in the
models hinting at a snow squall happening, there is still a lot of
variability in the models, especially with timing and with the
location of QPF. Most models are hinting at the most QPF and the
highest chance for precipitation to occur over northeastern SD while
the snow squall chances are more over central SD. Since this is
still a few days out, it will need to be watched to see if models
increase or decrease the chances of a snow squall happening by
shifting the CAPE, QPF, lapse rates, and winds on top of each other.
While most of the QPF and snow chances occurring over northeastern
SD, most of it looks to fall as rain before the temperatures
drop, leading to snowfall chances being more of a dusting. This
reduces the blowing snow chances, with patchy to areas of blowing
snow occurring mainly over far northeastern SD.

Even if a snow squall doesn`t occur, the models are still hinting at
the temperatures dropping like a rock overnight into Thursday
morning. NAM and GFS BUFKIT soundings are showing temperatures in
the northern SD sites dropping 10 degrees Celsius in an hour as the
cold front moves in, which goes from slightly above/around freezing
to -10 degrees Celsius. This is quite a drop, and will lead to high
temperatures being 5 to 15 degrees colder than normal on Thursday,
with highs in the teens to 20s. After Thursday, another upper-level
ridge moves over SD Friday, which helps support the high surface
pressure pushing into the state Thursday evening. This high pressure
has some WAA with it, which could help to temporally push out the
cold air from the day before, leaving highs being slightly warmer
than normal.

&&

.AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/...
Issued at 526 PM CST Mon Dec 15 2025

Terminals KABR,KATY,KPIR,KMBG

VFR conditions are expected to prevail through Tuesday. LLWS will
increase Tuesday as the jet mixes down early in the morning.

&&

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

$$

UPDATE...20
SHORT TERM...10
LONG TERM...12
AVIATION...20