Spearfish, South Dakota 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

471
FXUS63 KUNR 152306
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
506 PM MDT Thu May 15 2025

.KEY MESSAGES...

-Very strong northwest winds with gusts in excess of 60 mph
 expected across much of the western SD plains through Friday.

-Precipitation will shift back southwest into the FA tonight

-High elevation snow expected in the Black Hill tonight, mainly
 above 6 thousand feet

-Unsettled pattern continues into next week with another strong
 low pressure system bringing appreciable rain to the region
 Sunday and Monday.

&&

.DISCUSSION...(This Evening Through Thursday)
Issued at 213 PM MDT Thu May 15 2025

Deep closed upper low will retrograde back to the west and
support strong winds, rain, and some high elevation snow tonight
and Friday. The pattern remains fairly active into next week with
mean western CONUS toughing supporting another deep low pressure
system into the region early next week with widespread rains.
Upper low has begun to shift back west today with backside
subsidence, pressure falls, and increasing core of strong winds
aloft supporting increasing winds across the region. Have extended
the high wind warning further SW, including the Black Hills as
forecast soundings indicate a good environment for for strong
winds to mix down to the sfc at times. Steep lapse rates, dry air
system entertainment, and standing wave potential from terrain
should allow for frequent gusts over 50 mph with some gusts over
60 and even 70 mph possible, strongest on the NW SD Plains. This
setup is similar to the Oct 17-18 event from 2012. There will be a
lull in wind this evening at many areas before the stronger core
of winds push into the area late tonight and downward momentum
transport ensues. Rain will spread southwest overnight, backing as
far west as northeast WY. Expect that rain will change to snow in
the higher elevations of the Black Hills, mainly above 6 kft
where a few inches of wet snow will be possible. The wind combined
with the snow could certainly cause localized travel impacts.
Winds should peak Friday morning with winds slowly coming down
through the day. Rain will also shift back east and end by evening
most places. Skies will clear out with winds dropping off many
areas Friday night into Sat morning supporting the formation of
frost across far western SD and portions of northeast WY. A frost
adv may certainly be needed. Temps will warm up some Sat, but
still be below seasonal norms as the next system approaches the
area. Pos theta-e adv will ensue, supporting chances for showers
and storms in the afternoon and overnight Sat. As the system
shifts east, the associated trowel will remain over the region,
supporting a long duration of rain Sunday afternoon through Monday
night. Models still are indicating widespread amounts over an
inch across much of the FA, with the highest amounts (over 2
inches) expected along the eastern slopes of the BH where upslope
enhancement will be in place. Some high elevation snow will also
be possible with this system, esp areas above 6kft. Things will
dry out by the middle of the week, however semi-active westerly
flow will persists with near daily chances for showers continuing
along with seasonally cool temps.

&&

.AVIATION...(For the 00Z TAFS Through 00Z Friday Evening)
Issued At 503 PM MDT Thu May 15 2025

MVFR/IFR conditions will continue across northwest South Dakota
and rain persists through the forecast period. The rain will push
south/southeast overnight, bringing MVFR/IFR conditions back
toward the Black Hills area into northeast WY, and along the I-90
corridor in South Dakota. Strong northwest winds will continue
across the area through the forecast period, with gusts to 55 kt
Winds will gradually decrease after 18-19z Friday, although gusts
30-40 knots will persist into the last few hours of the forecast
period.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...High Wind Warning until 6 PM MDT /7 PM CDT/ Friday for SDZ001-
     002-012>014-025-026-031-032-041-043-044-046-047-072-073-077-
     078.
     High Wind Warning from midnight tonight to noon MDT Friday for
     SDZ024-028.
     Wind Advisory until 6 PM MDT /7 PM CDT/ Friday for SDZ027-030-
     042-049-074>076.
WY...High Wind Warning until 6 PM MDT Friday for WYZ060.
&&

$$

DISCUSSION/KEY MESSAGES...JC
AVIATION...SE