379
FXUS63 KUNR 091720
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1120 AM MDT Thu Oct 9 2025

.KEY MESSAGES...

- Mild through Saturday with gusty southerly winds Friday
- Upper level trough and cold front Sunday will bring colder
  temperatures, gusty winds, and chances for precipitation into
  next week

&&

.DISCUSSION...(Today Through Wednesday)
Issued at 152 AM MDT Thu Oct 9 2025

07z surface analysis had sprawling high over the Great Lakes with
weak trough over the CWA and cool front draped across northern
MT. Water vapour loop had southwesterly flow aloft with a compact
shortwave over central Canada and upper low off the northwest
CONUS coast. The effects of the these features the main forecast
concerns.

Today/tonight, central Canada shortwave moves southeast giving the
northern MT cool front a gentle nudge, sending it into the CWA later
today/tonight. Moisture will be limited, so plenty of solar
insolation will support MaxT near guidance. As high pressure slips
in tonight, clear skies and decreasing winds will support chilly
lows in the frost/freeze territory over northwestern SD. Day shift
can reassesses if headlines are necessary.

Friday, cooler lower tropospheric forecast soundings give
credence to MaxT 5-10F lower than today. As surface anticyclone
shifts east, robust return flow brings gusty southeast winds.
Friday night, low level jet spreads weak theta-e advection over
the SD plains which may pop some showers. Temperatures will be
near guidance.

Saturday, continued warm air advection under expanding thermal
ridge supports highs well into the 70s to around 80F. Upper
trough slides into the northern Plains by Sunday allowing a cold
front to plow through the CWA. Gusty northwest winds expected
behind it as well as a chance of showers. Forcing/moisture don`t
look too exciting at this point. Next week, mean upper
trough/cyclonic flow over much of western Canada/CONUS will
promote periodic chances for light precipitation and frontal
incursions. Low confidence in timing/strength of these systems,
but unsettled weather is probable as well as Fall-like
temperatures.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Friday)
Issued At 1118 AM MDT Thu Oct 9 2025

VFR conditions will prevail through the forecast period.

&&

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

$$

DISCUSSION/KEY MESSAGES...Helgeson
AVIATION...Smith