832
FXUS63 KUNR 120340
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
940 PM MDT Fri Sep 11 2026

.KEY MESSAGES...

- Cooler this weekend

- The next organized storm system is expected this weekend, with
  the best chance of showers and storms Sunday night

- Seasonal temperatures next week with mostly dry weather

&&

.UPDATE...
Issued at 927 PM MDT Fri Sep 11 2026

Cold front has cleared the FA. Have added some low pops through
tonight across most of western SD as an upper jet streak`s
associated entrance region traverses the area, possibly
supporting isold showers/sprinkles. Slightly better chances for
precip across far NW SD where weak FGEN forcing will also be in
place through Sat morning. Dry Sat with cooler temps, still
expecting highs in the 70s most areas, except for NW SD and the
Black Hills where 60s are expected. Breezy Sunday with moist
easterly upslope flow. This will hold temps down on the SD Plains
where 60s and 70s are expected. Main upper trough and associated
theta-e ridge will traverse the area Sunday night, supporting an
area of showers and storms, starting sct-isold out west then
filling in as the system progresses NE across western and central
SD. This is where the best chances for precip will be. Isold
stronger storms will be possible early on across SW SD if enough
low level moisture can advect into the FA ahead of the expected
impulse. Seasonal temps and dry most of next week with highs
mainly in the 70s, with 80s returning later in the week.

&&

.DISCUSSION...(This Afternoon Through Thursday)
Issued at 133 PM MDT Fri Sep 11 2026

Cooler weather is settling into the region today. It`s being
driven into the area by strong northerly to northwesterly winds.
Highest reported wind gusts (as of 1PM) have been upwards of 40
to 50 mph. For tonight, winds will slowly diminish through this
evening but speeds will really decrease mainly after 9PM.
Isolated rain and thundershowers are possible in the area that
stretches from NE WY to NW SD later this afternoon through
tonight. Severe weather is not expected and rain amounts won`t add
up to much.

Looking ahead to the weekend, temperatures will be at or below
normal for this time of year with highs reaching the upper 60s to
70s. Winds will slowly swing back to the east and southeast on
Saturday with wind speeds really increasing Sunday, afternoon
gusts will be upwards of 30 to 45 mph, strongest speeds in the SD
plains.

Isolated rain and thundershower chances return to the SD plains
Saturday into Saturday night but amounts will be on the lighter
side, mainly less than a quarter inch if anything. But Sunday into
Monday, a passing upper level trough north of the CWA will track
eastward. At the surface, low pressure will develop Sunday
afternoon and likely travel northeast. As it does, thunderstorms
are likely to track through the area late Sunday into Sunday
night. Some of those storms could be strong to severe. The SPC and
machine learning severe weather models are highlighting a marginal
risk of severe weather. Rainfall amounts Sunday into early Monday
will be mainly less than a half inch with locally higher amounts
possible.

Next week is looking dry with low-end chances for precip late in
the week with highs near or below normal for this time of year.

&&

.AVIATION...(For the 06Z TAFS Through 06Z Saturday Night)
Issued At 939 PM MDT Fri Sep 11 2026

VFR conditions are expected through the TAF period. Isold high
based shra are possible across western SD overnight into Sat
morning, best chances across far NW SD.

&&

.FIRE WEATHER...
Issued At 133 PM MDT Fri Sep 11 2026

A RED FLAG WARNING is in effect for SW SD and parts of NE WY until
7 PM MDT this evening. This is for strong, gusty northerly winds
and relative humidity down to 12 to 18 percent.

Looking ahead through the weekend, cooler weather is expected with
afternoon temps in the 60s to 70s. RH values will bottom out
around 30 to 50 percent. Wind gusts will be strong again tomorrow
(Saturday) for areas south and southwest of the Black Hills.
Sunday will see more widespread gusty winds in the WY and SD
plains. Similar weather expected next week.

&&

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

$$

UPDATE...JC
DISCUSSION...GS
AVIATION...JC
FIRE WEATHER...GS