545
FXUS63 KUNR 030857
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
157 AM MST Wed Dec 3 2025

.KEY MESSAGES...

- Upslope snow over the northern Black Hills diminishes this
  morning
- Colder today, following by a very slow warming trend
- Unsettled weather under northwest flow aloft into next week

&&

.DISCUSSION...(Today Through Tuesday)
Issued at 153 AM MST Wed Dec 3 2025

08z surface analysis had high pressure over central Canada which
was pushing a cold front south/southwest into the CWA. Cold front
extended from southeast MT to south-central SD. Water vapour loop
had splitting trough from central Canada to the Rockies slipping
southeast. Embedded shortwave over southeast MT assisting light
snow along/just ahead of the cold front per regional radar loops.
Upslope pulsing occurring from time-to-time over the northern
Black Hills. Northwest flow aloft will drive the weather during
the forecast period.

Today, MT shortwave moves through the area with residual
forcing/moisture along cold front keeping light snow going into
the morning hours. Subsidence/drying takes over this afternoon
except for perhaps southwest SD this afternoon, given lee side
convergence. Froude numbers/low level moisture supportive of
upslope-enhanced snowfall for the northern Black Hills/higher
northern/northeast foothills early this morning. Will keep Winter
Weather Advisory until 6am. After that, additional accumulations
an inch or less. Temperatures will be tricky today with current
readings above forecast highs, but feel cold air advection behind
cold front will be sufficient to push highs down into the 20s.

Tonight will be chilly as skies clear. Return flow develops for
Thursday with warmer temperatures on tap - pretty close to
guidance.

The rest of the forecast looks unsettled as speedy northwest flow
aloft slings a series of disturbances through the northern
Plains. We`ll be on the edge of the warmer air initially, but the
latest ensemble guidance shows a slow warming trend into early
next week, albeit with increasing temperature spreads. Best chance
of accumulating snow will continue to be over the northern Black
Hills given forecast boundary layer flow regime. But, can`t rule
out a quick shot of snow for anyone, especially at night.

&&

.AVIATION...(For the 06Z TAFS Through 06Z Wednesday Night)
Issued At 1015 PM MST Tue Dec 2 2025

Scattered snow showers will continue through the overnight hours,
with coverage and intensity picking up after 07-09z across far
western SD and NE WY. MVFR/IFR and transient LIFR conditions are
possible in snow showers. Downsloping conditions at KRAP are
resulting in fluctuating ceilings (MVFR to VFR and back), although
MVFR/IFR conditions are forecast to prevail after 10z. Conditions
will slowly improve from west to east by late Wednesday morning,
after 16-18z.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Winter Weather Advisory until 6 AM MST early this morning for
     SDZ024.
WY...Winter Weather Advisory until 6 AM MST early this morning for
     WYZ057.
&&

$$

DISCUSSION/KEY MESSAGES...Helgeson
AVIATION...SE