890
FXUS63 KUNR 070929
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
229 AM MST Fri Nov 7 2025

.KEY MESSAGES...

- Light rain/snow for the plains beginning tonight and continuing
  into Saturday morning

- Strong northwest winds Saturday morning, mainly over the western
  SD plains where gusts of 40-50 mph are likely.

- Accumulating upslope snow possible for the northern Black Hills
  Saturday

&&

.DISCUSSION...(Today Through Thursday)
Issued at 228 AM MST Fri Nov 7 2025

Shower activity has moved out of south central SD, leaving the
CWA under mostly clear skies as western CONUS ridge builds ahead
of our next system. 06z RAP mesoanalysis depicts vigorous
130-140kt upper level jet streak over the PNW with developing
shortwave trof. Winds will shift to the west this morning as the
ridge axis moves overhead. Weather will be mild and dry through
most of the day with highs in the 60s and light westerly winds.

Aforementioned jet streak will propel the shortwave eastward over
the Rockies through the day today with the system ejecting over
the Northern Plains by tonight. Sfc low will develop in the lee of
the Canadian Rockies and race southeastward into the Dakotas late
tonight/early Saturday morning. Initial cold front will sweep
through the CWA this evening, bringing the first round of precip
to the region. It will still be warm enough for precip to be
mainly light rain over the lower elevations (though we could see
some areas switch over to light snow tonight as cooler air filters
into the region) but it should be cold enough for snow in the
Black Hills. Some of the higher elevations could pick up a quick
inch or two of snow with the initial frontal passage. Secondary
front pushes through the CWA early Saturday morning bringing
another quick moving round of precip to the area, this time it
will be cold enough for snow to fall over the lower elevation of
the plains but given the recent warm temperatures and how light
the snow will be, not anticipating much accumulation over the
plains. Northwest flow and saturated moisture profiles should
support upslope snow over the northern Black Hills and Wyoming
Black Hills. In terms of amounts - NBM guidance paints >50% probs
for 2+" of snow over the higher elevations of the Black Hills near
the WY/SD border. Some deterministic guidance (HRRR, RAP, GFS)
have up to 4" of snow across these areas. All in all, not
anticipating the need for any winter wx headlines at this time.

In terms of winds, after the secondary front pushes through
Saturday morning, 3-hr pressure rises of 3-5 mb and CAA will
support strong northwest winds, primarily across the western SD
plains. BUFKIT soundings show 45-55kt winds just off the surface
in the usual squeeze areas along the Black Hills from around
Newell to Scenic. Still on track to see these areas reach solid
Wind Advisory criteria Saturday morning with NBM probs of 70-80%
for wind gusts to exceed 50 mph. Chances for high wind warning
criteria (60+ mph gusts) lower with NBM probs of ~20-30% for those
spots.

Deterministic and ensemble guidance in consensus of trough
amplifying over the eastern CONUS later this weekend into early
next week as upper ridge builds in the west. This will translate
to mild temperatures and mostly dry weather for the region with
the occasional weak disturbance bringing breezy winds to the
region.

&&

.AVIATION...(For the 06Z TAFS Through 06Z Friday Night)
Issued At 1028 PM MST Thu Nov 6 2025

Westerly winds under 15 knots prevail tonight and become less than
10 knots for a time daytime Friday. An approaching cold front
first crosses far northwest SD and northeast WY after 20Z and
builds shower chances northwest to southeast from 21-03Z. Expect
a quick return to gusty northwest winds too underneath the
frontal passage. Shower are forecast to enter the KGCC TAF area
after 22Z and a couple of hours later at KRAP. A 4-5 hour period
of vicinity showers hours is expected to prevail under the frontal
passage, along with a low-end (20-30% chance) or scattered rain
showers at both terminals so PROB30s were also placed at both
terminals with this TAF issuance. Winds look to cut off slightly
immediately post-frontal, but a period of low-level wind shear
then builds into Friday night ahead of the very strong winds
gusting 35-45 knots that are possible after 09Z Saturday ans
lasting into Saturday afternoon.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...High Wind Watch from late tonight through Saturday afternoon for
     SDZ012-013-031-072-073.
WY...None.
&&

$$

DISCUSSION/KEY MESSAGES...Wong
AVIATION...NL