962
FXUS63 KUNR 162348
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
448 PM MST Sun Nov 16 2025

.KEY MESSAGES...

- Compact upper low will bring a shot of precipitation to the
  area late tonight/Monday
- Seasonally cool and Tuesday through next weekend
- Pattern change for Thanksgiving?

&&

.DISCUSSION...(This Evening Through Sunday)
Issued at 129 PM MST Sun Nov 16 2025

20z surface analysis had elongated trough from central MT into
central CO. High pressure sprawled across the upper Midwest into
the mid-Mississippi river valley. Modest southeasterly return
flow over the CWA with 0.5km visible loop depicting plenty of
sunshine over the area. Water vapour loop showed upper ridge over
the Northern Plains ahead of upper low over NV, which is the main
forecast concern.

Tonight/Monday, compact upper low ejects into the central Plains
in response to energy diving into the western CONUS. Increasing
clouds expected tonight ahead of upper low as mid-level moisture
increases. Modest band of 800-600mb frontogenesis arcs through the
CWA Monday as QG-forcing slides through ahead of the upper low.
Initial lift will be wasted on saturation, but by Monday morning,
east/west-oriented band of rain expected from northeastern WY
into western SD. This is consistent with HREF guidance PoPS with
QPF amounts Monday 0.10"+ (>70% chance except for south-central
SD). Probably less than 0.25" most places (<30% chance >0.25").
Elevated buoyancy hard to find, but very weak MUCAPE near the
SD/NE border may be sufficient for weak convection, so have
introduced thunder. Have lowered temperatures a bit given expected
cloud cover and precipitation coverage.

Tuesday through next weekend, mostly split flow expected as weak
disturbances slip through. Result will be seasonally cool
temperatures and periodic lowish chances for precipitation.
Confidence drops as the weekend approaches given complex upper
flow and increasing probabilistic temperatures spreads.

Looking into ensemble model dreamland, latest indications suggest a
pattern change for Thanksgiving - colder/whiter. Stay tuned.

&&

.AVIATION...(For the 00Z TAFS Through 00Z Monday Evening)
Issued At 447 PM MST Sun Nov 16 2025

VFR conditions are expected tonight. A storm system will cross
the area on Monday, bringing widespread MVFR/IFR conditions to
western SD and much NE WY....especially mid-morning onward. Rain
will develop across west central SD including the Black Hills
eastward toward the central SD plains. Light snow is possible in
the higher Black Hills. Precip will start Monday morning and
continue through the evening hours.

&&

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

$$

DISCUSSION/KEY MESSAGES...Helgeson
AVIATION...13