017
FXUS63 KUNR 231100
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
400 AM MST Sun Nov 23 2025

.KEY MESSAGES...

- Mild and dry end to the weekend.

- Pattern change late Monday behind a strong cold front, with
  light snow late Monday and early Tuesday.

- Even colder air expected late next weekend with better chances
  for widespread accumulating snow.

&&

.DISCUSSION...(Today Through Saturday)
Issued at 159 AM MST Sun Nov 23 2025

Upper level analysis shows subtle ridging over the Northern
Plains with brisk northwest flow displaced northward near the
Canadian border. A closed upper low is slowly ejecting out of the
desert SW into the central and southern Plains this morning.
Surface high pressure has settled across SE NE and E KS with a
surface trough stretching from E MT through NE WY.

Mild and dry today with ample sunshine as highs push into the 50s
and low 60s, particularly across the far western SD plains and
eastern foothills. Breezy westerly winds coupled with dry air will
result in areas of elevated fire weather conditions.

The desert SW low is forecast to eject into the central Plains by
12z Monday as an open wave. Weak frontogenesis and warm air
advection will overspread south-central SD early Monday with a few
light rain showers possible, although precipitation amounts will
be minimal.

Immediately following this, another shortwave will drop through
the region late Monday into early Tuesday. A strong cold front
will move through late Monday evening, bringing much colder air to
the forecast area Tuesday. Chances of rain and snow will increase
Monday evening, with precipitation changing to all snow as cold
air filters in. This system will move through the area quickly
with dry air filtering in, limiting the best chances of
accumulating snow to the northern Black Hills (probability snow
>2" ~30%) with an inch or so possible across NW SD.

Strong NW winds will follow the frontal passage with widespread
advisory level winds likely Tuesday morning through the afternoon
hours. Cold air advection + steep low-level lapse rates + 40-50
knot winds atop the mixed layer may support a period of warning
level winds (>60 mph gusts). Ensemble data supports this with
GEFS/EPS painting ~30-50% chance of warning criteria winds across
portions of the western SD plains Tuesday (NBM probabilities are
much higher and more expansive: widespread 50-75%+). Will continue
to monitor; any snow plus the strong winds will result in areas of
hazardous travel/reduced visibility Tuesday.

Deeper western troughing is forecast Thanksgiving weekend,
although considerable uncertainties remain. Will continue to
monitor for the potential of more widespread accumulating snow,
although confidence is low on timing and exact amounts. High
confidence does exist that even colder air will spill into the
region late next weekend.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Monday Morning)
Issued At 359 AM MST Sun Nov 23 2025

VFR conditions are expected through the TAF period.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...None.
WY...None.
&&

$$

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