338
FXUS63 KUNR 092131
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
231 PM MST Tue Dec 9 2025

.KEY MESSAGES...

- High Wind Warning remains in affect for much of western SD.
  Expect wind gusts up to 65 mph.

- Winter Weather Advisory is now in affect for northwestern SD
  from tomorrow night through Thursday morning.

- Potential for a winter storm to impact the area on Friday
  through Saturday.

&&

.DISCUSSION...(This Evening Through Tuesday)
Issued at 1249 PM MST Tue Dec 9 2025

Rest of today...Winds picked up a little later than anticipated
but widespread wind gusts in the 55-65 mph range have been
observed over the past hour. Localized stronger wind gusts over
65 mph are occurring in areas where precipitation has developed.
Expect this trend to continue through the rest of the afternoon.
Winds will quickly diminish through the overnight hours but we
will hang on to the scattered precipitation across the region.

Immediately behind this current system that has brought the winds
to region, the next system is following closely behind. An area of
low pressure over the MT Rockies on Wednesday will slide SE,
arriving to the CWA on Thursday. Strong overrunning will support
700mb frontogenesis/isentropic lift on Wednesday, bringing
widespread light snow in the morning, then becoming rain through
the day as warmer air advects in from the west. he broad band of
snow over central South Dakota could become freezing rain as
warmer air aloft noses in. Ice accumulations have increased
slightly in this latest forecast package, especially across
northwestern SD. With the combination of snow, rain/snow and then
freezing falling in the same locations with ice accumulations
approaching a tenth of an inch, the Winter Weather Advisory was
issued. Additionally ice conditions may continue even after the
precipitation has stopped as wet roads and power lines may flash
freeze with the strong CAA expected across these areas as we
progress into the evening hours on Thursday ahead of the next
storm system.

Models are beginning to agree on the end of the week system in
terms of targeting northwestern SD for the potential for some
accumulating snows around 6". With locations to the south seeing
only 1-2", with this sharp gradient we need to continue to monitor
the evolutions and tracks the models show to pinpoint just where
the heaviest snows will fall.


&&

.AVIATION...(For the 18Z TAFS Through 18Z Wednesday)
Issued At 959 AM MST Tue Dec 9 2025

Areas of MVFR/IFR conditions due to lower clouds/ra/sn will
affect northeast WY/northwest SD today. Otherwise VFR conditions
expected over southwest into south-central SD. Strong winds
gusting to +50kt are expected across much of the western SD plains
today before slowly decreasing this evening and overnight.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...High Wind Warning until 2 AM MST /3 AM CST/ Wednesday for SDZ001-
     002-012>014-025>027-030>032-041>044-046-047-049-072>078.
     Winter Weather Advisory from 5 PM Wednesday to 11 AM MST
     Thursday for SDZ001-002-012>014-032-078.
WY...High Wind Warning until 2 AM MST Wednesday for WYZ060.
&&

$$

DISCUSSION/KEY MESSAGES...Woodward
AVIATION...Smith