Spearfish, South Dakota 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

430
FXUS63 KUNR 041115
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
515 AM MDT Mon May 4 2026

.KEY MESSAGES...

- A cold front will cross the region Monday morning, bringing
  gusty northwest winds behind it as well as some light showers
  over the course of the day.

- A Wind Advisory is in effect for the northwestern South Dakota
  plains where difficult driving for high profile vehicles is
  expected due to wind gusts as high as 50 MPH.

- Mean northwest flow aloft will bring continued unsettled
  weather through next weekend.

&&

.UPDATE...
Issued at 1033 PM MDT Sun May 3 2026

No major changes with this evening`s forecast update. Slightly
expanded coverage of low PoPs for Monday to account for light
shower potential over the course of the day. Only minor tweaks
made to NBM winds/wind gusts, which continue to support the low-
end WIND ADVISORY already issued across the northwestern South
Dakota plains. A few other locations across the CWA could briefly
gust to 45 MPH along and immediately behind the front, but the
advisory area remains favored for 45-50 MPH peak gusts with the
primary impact being difficult driving for some high-profile
vehicles. Cooler high temperatures compared to today will range
from the low 50s to low 60s Monday.

&&

.DISCUSSION...(This Evening Through Sunday)
Issued at 1203 PM MDT Sun May 3 2026

17z surface analysis had weak trough from the Big Horns into the
NE panhandle. Trough reflection of compact shortwave over the Big
Horns per water vapour loop. 0.5km visible satellite matinee
depicted agitated CU/TCU field associated with these features.
Few lightning strikes near the Big Horns with slowly increasing
radar returns over the Black Hills. ~250J/kg SBCAPE out there,
forecast to peak around 500J/kg per SPC HREF. Result will be
scattered shra/isolated TS through early this evening over the
southwest half of the CWA. Enough 0-6km bulk shear to help a storm
if buoyancy were higher, but wouldn`t be surprised to see a storm
put out a 30-40kt wind gust given the 18z KUNR sounding.

After the precipitation ends early this evening, next upstream
shortwave trough careens southward into the northern Plains late
tonight/Monday morning pushing a cold front through the CWA.
Decent pressure rises behind front with forecast soundings
depicting well-mixed boundary layer late Monday morning into the
afternoon hours. Result will be gusty northwest winds at times,
especially from K2WX-KRCA where NBM probability of >45mph wind
gusts is 40-70%. Have hoisted a Wind Advisory to account. Band of
800-600mb frontogenesis will support scattered showers
potentially enhancing downward momentum transfer. Temperatures
will be cooler/near guidance.

Mean northwest flow aloft continues for Tuesday through next
weekend with a parade of shortwaves/surface fronts. Result will be
isolated/scattered showers at times. Temperatures will be 5-10F
below normal Tuesday/Wednesday, but then rise to 5-10F above
normal for the weekend. Confidence is fairly high until next
weekend when typical ensemble guidance spreads come into play.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Tuesday Morning)
Issued At 513 AM MDT Mon May 4 2026

VFR conditions are expected tonight. A cold front crossing the
area at this time will bring gusty winds today. The strongest
winds will be during the day across NW SD with gusts up to 45kt.
Light showers (and perhaps MVFR CIGS) are also expected today
especially toward the late the afternoon. If the rain showers
linger across the Black Hills late enough, it could change to
snow, resulting in IFR conditions. VFR conditions will return
tonight.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Wind Advisory from 9 AM this morning to 6 PM MDT this evening
     for SDZ001-002-012-013-073-078.
WY...None.
&&

$$

UPDATE...KSmith
DISCUSSION/KEY MESSAGES...Helgeson
AVIATION...13