855
FXUS63 KABR 032339
AFDABR

Area Forecast Discussion
National Weather Service Aberdeen SD
539 PM CST Wed Dec 3 2025

.KEY MESSAGES...

- Patchy fog possible over portions of northeastern SD late this
  evening into the early morning hours Thursday.

- Cold temperatures expected tonight with lows in the single
  digits below and teens below zero. Wind chill values will range
  in the teens and twenties below zero east of the Missouri River.

- Downslope winds expected in the Sisseton Hills region on
  Thursday, with gusts potentially over 40 mph. This may create
  areas of blowing/drifting snow.

- Snow chances (20-40%) return Friday and Saturday through early
  next week as more weather systems have the potential to move
  through the region.

&&

.UPDATE...
Issued at 539 PM CST Wed Dec 3 2025

Patchy fog has been added to portions of northeastern SD late this
evening into the early morning hours Tuesday, before winds
increase out of the south near/just prior to 12Z. Otherwise, the
ongoing forecast remains unchanged at this time.

&&

.DISCUSSION...
Issued at 216 PM CST Wed Dec 3 2025

As of 2pm, satellite indicates clear skies James Valley and eastward
with stratus clouds continuing over central South Dakota and
upstream through western ND. Current temperatures range in the
single digits to the mid teens, warmest over south central SD. A
1035mb arctic high will be directly overhead by this evening,
tracking southeast through the overnight with the center of the high
over IA by 12Z Thursday. Winds will diminish west to east across the
CWA through this evening becoming light through about 06Z. Models
indicate the coldest temperatures will be around the 06Z timeframe
before winds shift out of the south/southwest and WAA moves in as
the CWA will be on the downstream side of a surface trough that will
be positioned south of a low in Canada. HREF grand ensemble 925mb
temps look to range between -9 to -17C at 06Z, coldest James Valley
and eastward and 850mb temps of -10 to -15C. Kept the trend of
dropping the surface temps below mean NBM guidance, closer to the
25th percentile. Forecast lows range from the single digits above
zero to around 11 degrees west of the Mo River to the single digits
to the teens below zero east of here, coldest over the James Valley.
Minimum wind chill values east of the Mo River are forecast to range
in the teens to twenties below zero. With the WAA after midnight, we
will see temps rise from west to east across the CWA, with temps by
12Z Thursday ranging from the single digits below zero to the lower
teens, highest over south central SD. As the surface trough/warm
front track east across the CWA through the day Thursday, highs will
be warmer ranging in the 20s and 30s!

Our next concern will be the gusty winds over and downslope of the
Coteau for Thursday as we see an area of higher winds on the
downstream side of this 925/sfc trough over the eastern Dakotas into
western MN. HREF 925mb winds indicate speeds between 30-40mph out of
the southwest at the top of the inversion layer. HREF is showing
surface gusts of 30-45mph with NBM max gusts around the same.
Comparing NBM/NBM5.0 is pretty close, about 5kts higher in any one
location. The highest winds at 925mb, therefore, the highest gusts
at the surface will be in the morning through the late afternoon
with winds diminishing towards the evening. EC EFI does highlight
this potential well with pockets of 0.6 to 0.7 with EFI of zero for
the downsloping wind gusts. Drifting to patchy blowing snow is
expected, luckily with the warming temps expected and snow age this
should prevent any lofting/widespread blowing snow.

Through at at least early next week we continue in a persistent
northwest flow pattern with a near stationary mid level low over the
Hudson Bay and a ridge to our west. Models indicate several embedded
shortwaves/lows tracking southeast and over the Northern Plains
through the extended. With the low mentioned above tracking across
Canada Thursday/Friday and its shortwave, HRRR along with ENS/GEFS
indicate the chance of flurries/light snow ahead of a cold front
late Thursday night through Friday within this surface trough. NBM
did not show anything so with collab from the offices, we increased
pops and used WPC for QPF to show for this. Pops range from 15-30%
Friday with a couple tenths of snow accumulation possible over north
central through northeastern SD. Our more notable wave/Clipper low
looks to possibly affect the region Saturday, however low confidence
exists due to model disagreement at this time on track and intensity
of low and where the "highest snowfall" may occur. GEPS has a track
more over central SD and ENS more across the northern CWA. NBM
probability of 24hr snow ending 12Z Sunday>0.10" is 45-70% with 25%
or less for an inch of snow. The good news for now is that we are
not expecting heavy snow for any one period during the extended.

&&

.AVIATION /00Z TAFS THROUGH 00Z FRIDAY/...
Issued at 539 PM CST Wed Dec 3 2025

Terminals KABR,KATY,KPIR,KMBG

Patchy fog with MVFR to IFR ceilings and visibility has been
added for ABR and ATY from around 05-11Z, before winds increase
out of the south near/just prior to 12Z when winds increase to
10kts with higher gusts in excess of 20kts after 14Z. MVFR
ceilings remain at MBG and PIR, with the cloud deck expected to
move east of those locations 04-08Z Thursday. Otherwise the main
concern this period will be 25-30kts winds at ATY during the day
Thursday, while 20-26kts at ABR.

&&

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

$$

UPDATE...06
DISCUSSION...MMM
AVIATION...06