541
FXUS63 KUNR 150351
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
951 PM MDT Fri Aug 14 2026

.KEY MESSAGES...

- Active pattern persists through the weekend with daily chances
  of showers and thunderstorms.

- Increased severe weather potential Sunday through Tuesday,
  although details remain uncertain.

&&

.DISCUSSION...(This Evening Through Friday)
Issued at 115 PM MDT Fri Aug 14 2026

Active southwest upper level flow continues with southeasterly
surface flow. Surface dew points range from the upper 50s in
Wyoming and the Black Hills to mid 60s across western South
Dakota. Low clouds eroded through the morning with surface heating
driving temperatures into the upper 70s and low 80s. SPC
mesoanalysis and the 18z KUNR RAOB show 500-1000 J/kg MLCAPE
across the area with effective bulk shear around 30 to 40 knots.
Scattered convection is trying to develop across NW SD and NE WY,
although coverage may be limited until a shortwave arrives later
this afternoon and early evening. Widespread severe weather is not
anticipated, however isolated strong to severe storms are
possible given the instability and shear parameter space.

Daily chances for showers and thunderstorms will persist through the
weekend into early next week. Upper level flow is forecast to become
more zonal/northwesterly early next week into mid week. Severe
potential increases Sunday and Monday with ample instability and
shear around 35 to 50 knots. Severe potential may stretch into
Tuesday, but timing of the wave and location of the surface front
remain uncertain.

Longer range guidance shows a strong area of high pressure building
over the SW US by end of next week into the weekend with
temperatures trending warmer for our area.

&&

.AVIATION...(For the 06Z TAFS Through 06Z Saturday Night)
Issued At 950 PM MDT Fri Aug 14 2026

Isolated to scattered showers and storms will be possible through
the forecast period. Transient MVFR/IFR conditions are expected
around any heavier precipitation cores. Pockets of fog may
develop in the overnight hours, however widespread fog is not
expected. MVFR/IFR cigs are expected early Saturday morning north
of our forecast area, and may creep into far northeastern WY and
northwestern SD, before burning off late morning.

&&

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

$$

DISCUSSION...SE
AVIATION...Dye