311
FXUS63 KUNR 092050
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
150 PM MST Sun Nov 9 2025

.KEY MESSAGES...

- Chilly tonight with lows in the teens to 20s and wind chills
  dipping into the single digits over the western SD plains.

- Warm and dry beginning Monday with highs 10-15F above average

&&

.DISCUSSION...(This Evening Through Sunday)
Issued at 1227 PM MST Sun Nov 9 2025

The Northern US Plains remains in northwesterly mean flow aloft at
500 mb height analysis as a deep low pressure sits over the Upper
Great Lakes to the east and a notable high pressure centered over
the Southwest extends a high amplitude ridge into the Pacific NW.
A stripe of low-level stratus clouds will continue to dissipate
yet this afternoon over far western SD Plains with clear skies on
either side of this stratus. While the low-level airmass aloft
does warm through tonight, seasonable chilly temperatures will
occur into early Monday morning over mainly the SD Plains.
Forecast minimum wind chills tonight drop into the low-single
digits above zero closer the Missouri River valley region, while
closer to the mid- teens towards the WY/MT stateline region on the
Plains.

As surface high pressure aids in creating near-surface southerly
return flow Monday underneath that warming airmass aloft. These
conditions will help to create forecast surface temperatures
Monday daytime in the low-50s along the Missouri to mid-60s in
northeast Wyoming and downslope of the Hills.

A clipper crossing over the Northern US High Plains Monday
evening helps to create a wind shift to westerly then
northwesterly Monday PM and night over the forecast area. As this
dry cool front crosses over the area, mid-level Pacific moisture
is likely to create some passing clouds. Model forecast soundings
do not support much more than sprinkles to virga at this time
though so kept without any mentionable rain chances into Tuesday
morning. Any additional moisture advection that sticks with this
clipper could need some low-end mentionable precip chances in
future forecasts.

Gusty post-frontal northwesterly winds prevail Tuesday, gusting
35 to 45 mph, over the western SD Plains even as the seasonable
warm temperatures persist. As southerly to easterly winds set up
again for Wednesday and Thursday, this pattern of warm and dry
weather will persist at least into Friday daytime.

Global ensemble guidance progs show some form of a deep and cool
Pacific longwave trough building over the Rock Mountains Friday
daytime. How fast this ejects into the Central US, and in what
form, will be a large influence on the SD / US Great Plains
weather pattern for Friday night into Saturday. Right now there is
a 30-40% chance of this system bringing a rain and high elevation
snow mix to the forecast area in this early-weekend time period.
Keep an eye on the forecast for the track and timing of this late
week weather system for any possible winter weather impacts,
especially in the high elevations.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Monday)
Issued At 1021 AM MST Sun Nov 9 2025

A strip of MVFR/IFR stratus from southeast MT to the NE panhandle
will dissipate this afternoon, likely going away at the KRAP
terminal around 20z. Otherwise, VFR conditions expected through
the period.

&&

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

$$

DISCUSSION/KEY MESSAGES...NL
AVIATION...Helgeson