613
FXUS63 KUNR 021718
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1118 AM MDT Thu Oct 2 2025

.KEY MESSAGES...

-Warm through the end of the work week, with record to near
 record warmth Friday

-Elevated to near critical fire weather conditions for portions
 of the area today and especially Friday

-Pattern change will commence this weekend, with rain, wind, much
 cooler temperatures, and even some high elevation snow possible

-Forecast confidence tails off next week given lack of forecast
 model consensus

&&

.DISCUSSION...(Today Through Wednesday)
Issued at 149 AM MDT Thu Oct 2 2025

Digging western CONUS trough will allow for an array of weather
the next few days as this system shifts east and phases with a
deep northern stream trough. WAA ensuing across the region this
morning, with deep layer SW flow. Upper ridge will build over the
region ahead of this trough and allow for fairly warm temps for
early October, esp Friday when many locations will see highs above
90. Upper trough will shift east and phase with a deep southern
Canadian upper trough as a plume of Pac moisture shifts northeast
into the region, forcing a cold front into the area Sat. Precip
chances will ensue during the day Sat with a convective component
at first, supporting chances for showers and isolated TS. However,
the best chances for precip will be Sat night when the best
overlapped of lift, moisture, and convergence shifts over the
region. Ongoing CAA will allow for rain to mix with or change
over to snow in the higher elevations of the BH and perhaps
portions of northeast WY. Not expecting any accums given warm
ground temps and limited window for snowfall. Given strong forcing
and slow system progression per phasing, expecting many locations
across the western 2/3 to see a half to one inch of rain. The
other impact of this system will be gusty NW winds which will
develop Sat night into Sunday with gusts over 50 mph likely on the
SD Plains, potentially higher in some model members. Much cooler
weather will arrive for the first part of next week with highs in
the 50s on the Plains and 40s in the BH. Forecast models start to
depart wrt details on the flow pattern next week, particularly the
degree of western NOAM ridging and the interaction of an expected
NE Pac upper trough, which will highly impact the local weather.
Right now, the forecast is biased toward more seasonal temps and
mainly dry weather, but that may very well change.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Friday)
Issued At 1118 AM MDT Thu Oct 2 2025

VFR conditions will continue through the forecast period.

&&

.FIRE WEATHER...
Issued At 149 AM MDT Thu Oct 2 2025

Elevated fire weather conditions can be expected today mainly
across northeast WY and southwest SD. Although RH`s will drop to
around 15 to 20 percent, winds will be generally light today.
Warmer temperatures, deeper mixing, and breezy southwest winds are
expected Friday for much of the area. RH`s will fall to around 10
to 15 percent across northeast WY and much of southwest SD in the
afternoon with breezy southwest winds developing (frequent gusts
over 25 mph likely). Given dry fuels and these concerns, issued a
fire weather watch for Friday afternoon for much of northeast WY
and southwest SD.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Fire Weather Watch from Friday afternoon through Friday evening
     for SDZ320>322-324>326-329-332.
WY...Fire Weather Watch from Friday afternoon through Friday evening
     for WYZ314>317.
&&

$$

DISCUSSION/KEY MESSAGES...JC
AVIATION...Smith
FIRE WEATHER...JC