Rapid Valley, South Dakota 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

220
FXUS63 KUNR 290459
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1059 PM MDT Sun Jun 28 2026

.KEY MESSAGES...

- Severe thunderstorms with large hail and damaging winds expected
  overnight across western SD, mostly east of the Black Hills.

- Strong winds expected Monday, with elevated to near-critical
  fire weather conditions.

- Cooler Monday, but gradual warmup through the week.

&&

.UPDATE...
Issued at 1052 PM MDT Sun Jun 28 2026

A Severe Thunderstorm Watch is now in effect for portions of our
south-central South Dakota plains overnight. Very strong deep-
layer shear in excess of 65kts will favor supercells, and while a
shallow stable layer may be present at the surface suggesting
storms may be elevated, very thick mid-level CAPE profiles in
forecast soundings with over 3,000 J/kg MUCAPE possible will
support a very large hail threat. Convection may also be enhanced
by gravity waves increasing a damaging wind threat with time,
with some HRRR and RRFS guidance hinting at gusts over 80 MPH in
far eastern portions of our CWA. A non-zero tornado risk exists as
well with notable SRH, but the elevated nature of the storms may
keep this risk low. Will also be watching for swaths of very heavy
rain with storm training, with localized flash flooding not
impossible...especially if storms train over areas that saw
significant rainfall last night in our southern/eastern counties.
Largely went with NBM and WPC guidance in the forecast, but
adjusted PoPs and QPF to better match current radar trends and the
new 00z HREF suite including CAMs. Breezy conditions remain
expected Monday, and no changes were made to the ongoing WIND
ADVISORY. These winds, along with minimum afternoon RH values of
12-18 percent, may support near-critical fire weather conditions
especially from the Weston County area into the far southwestern
South Dakota plains. Some areas have seen recent rainfall but may
still carry critical fuels...confidence remains just low enough
that we will continue to monitor these conditions and not issue a
Red Flag Warning with this update.

&&

.DISCUSSION...(This Evening Through Sunday)
Issued at 1208 PM MDT Sun Jun 28 2026

Current Water Vapor and upper air models show the upper low
currently over north central MT, with southwest flow over the
forecast area. 17Z Surface analysis shows a boundary running from
northwestern SD down into southeastern WY. Winds are currently
light out of the south to southwest. Radar has some light returns
in northwestern SD moving northeast into ND.

Main concern in the near-term will be potential for severe
thunderstorms tonight into Monday morning. Mostly dry conditions are
expected this afternoon, but southeasterly LLJ ramps up this evening
into the overnight hours, bringing moisture into the region. Surface
low is expected to develop over northeastern CO and move
northeastward into the area by tonight. As low enters the region and
LLJ increases, strong to severe storms are expected to develop.
While we could see some showers/storms develop in the early evening,
HREF and HRRR show the stronger storms starting up between 03-06Z.
CAMS currently show strong to severe storms developing in
southwestern SD and the Black hills in this timeframe, then moving
northeast. Thermal profiles will support elevated storms with hail
being the main threat from these, however strong to severe wind
gusts cannot be ruled out.

Monday will be dry but windy, as strong mixing will support wind
gusts 45 to 55 mph. A Wind Advisory has been issued for much of
western SD, including the foothills late morning into the early
evening. Another shortwave is progged to move through the
central/northern plains late Tuesday into Wednesday, supporting
the potential for some showers/storms. Southwest flow continues
though the week, with weak disturbances prompting near daily
chances for at least isolated precipitation the latter half of the
week. Upper high in southeastern CONUS also builds over the week,
supporting a gradual warmup. Temperatures climbing into the 90s
will be possible Thursday through Saturday.

&&

.AVIATION...(For the 06Z TAFS Through 06Z Monday Night)
Issued At 1054 PM MDT Sun Jun 28 2026

Strong thunderstorms are making their way north out of NE and
into southwestern SD. Some isolated storms may impact KRAP through
the night. As the storms exit western SD early Monday morning,
VFR conditions are expected throughout the forecast period. Strong
winds are expected across the area Monday afternoon (widespread
35+ mph), particularly in southwestern SD. The strongest gusts may
be up to 55 mph. These will mellow out after sunset Monday.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Wind Advisory from 10 AM to 8 PM MDT Monday for SDZ012-013-
     025>027-030-031-041-042-072>076.
WY...None.
&&

$$

UPDATE...KSmith
DISCUSSION...Dye
AVIATION...Schweigert