Spearfish, South Dakota 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

729
FXUS63 KUNR 111057
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
457 AM MDT Fri Apr 11 2025

.KEY MESSAGES...

- Dry and breezy weather will result in near-critical fire weather
conditions today.

- A low pressure system will bring a chance for precipitation late
Saturday into Monday. The cold front will bring strong winds Sunday,
along with a cooldown Sunday into Monday.

&&

.DISCUSSION...(Today Through Thursday)
Issued at 129 AM MDT Fri Apr 11 2025

The upper ridge is crossing the Rockies, and the surface high is
currently centered over northeastern NE. High clouds are pushing
into the western Dakotas. Winds are light and variable, and
temperatures are in the 40s and 50s.

As the surface high shifts eastward, southerly return flow will
develop across the western SD plains. Winds will be around 15 mph,
with gusts of 20 to 25 mph. Warm air will advect into the region,
with highs reaching the 70s to lower 80s. Lows tonight will be
mainly in the 40s.

Meanwhile, a shortwave trough will move ashore over the Pac NW. The
surface low will slide through SD early Saturday, with cooler air
wrapping around it, along with some precip in the afternoon and
overnight. With highs in the 60s and 70s, rain showers and isolated
thunderstorms are expected, mainly across northeastern WY, the Black
Hills, and northwestern SD. Although MLCAPE and MUCAPE are
generally less than 500 J/kg, strong 0-6 km shear could help
produce some stronger storms. Some very light snow will be
possible over the Black Hills early Sunday morning, as
temperatures cool into the 30s.

Chances for precip will continue mainly over the northwestern CWA,
as the upper shortwave slides into ND. Early Sunday, the main cold
front will slide through the region, bringing strong northwest winds
and colder temperatures. Gusts of 50 to 60 mph will be possible,
especially across northwestern SD. Highs will range from the 40s to
lower 60s. A reinforcing shot of cold air and strong winds will
follow closely behind Sunday night.

Models and cluster analyses still indicate ridging towards the
middle of next week, with a warmup possible Tues/Wed. However,
deterministic models start to diverge and the cluster analyses
appear a little more troughy, so confidence is low on the overall
weather pattern of next week.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Saturday Morning)
Issued At 456 AM MDT Fri Apr 11 2025

VFR conditions are expected through the forecast period.

&&

.FIRE WEATHER...
Issued At 129 AM MDT Fri Apr 11 2025

Today will be warm and very dry, with highs in the
70s to lower 80s, and RH dipping to 10-15%. Southerly winds will be
breezy, sustained around 15 mph, with some gusts up to 25 mph. These
strong gusts are not expected to be frequent, and may be in the late
morning (before RH reaches 15%), and so the wind gusts may not align
well enough with the driest afternoon RH to warrant a Red Flag
Warning. However, it will be close, and conditions will be near-
critical.

Mild and dry weather will continue Saturday, but nearly as dry (min
RH 18-28%) and not very windy. Very strong winds arrive Sunday
behind a cold front.

&&

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

$$

DISCUSSION/KEY MESSAGES...Pojorlie
AVIATION...Helgeson
FIRE WEATHER...Pojorlie