000
FXUS63 KUNR 171832
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1232 PM MDT Sun Aug 17 2025

.KEY MESSAGES...

- Marginal risk (1/5) for severe thunderstorms today and tomorrow
  across the Black Hills.

- Turning hot and dry Tuesday through Thursday. Could see upper
  90s to near 100F by Wednesday.

- Turning cooler with unsettled weather returning by next weekend.

&&

.DISCUSSION...(This Evening Through Sunday)
Issued at 1219 PM MDT Sun Aug 17 2025

Satellite shows an agitated cumulus field developing across the
Black Hills where a small thundershower has developed across
Custer county. Expecting and increase in shower and thunderstorm
development as the cap continues to erode as we continue to
steepen the lapse rates and increase instability. With surface
dewpoints into the mid to upper 60s and temperatures climbing into
the 80s, MLCAPE values are progged to climb north of 1500 J/kg by
the late afternoon hours. With limited upper level support and low
0-6km shear values storms should go up fast and dissipate quickly
as the low shear will keep the updraft/downdraft in close
proximity of each other, this translates to the potential for
thunderstorm cores to produce small hail, but also some damaging
downburst wind gusts in the strongest/tallest cores. These storms
will also struggle once they leave the terrain and enter a less
favorable environment. The best parameters for a window for
organized convection will be across central South Dakota/Nebraska
border where there is slightly better upper level support. These
scenarios of late afternoon convection transitioning into clusters
of thunderstorms during the overnight hours will once again play
out tomorrow as similar conditions remain in place across the area
with just subtle differences in the available upper level support.

Heading into Tuesday, a large upper level ridge will dominate over
much of the central CONUS bringing much drier conditions and hot
temperatures to the region. This feature per model solutions will
remain in place throughout much of next week before gradually
moving out in advance of the next weather system that will bring
cooler temperatures and chances for thunderstorms back into the
forecast by next weekend.


&&

.AVIATION...(For the 18Z TAFS Through 18Z Monday)
Issued At 1116 AM MDT Sun Aug 17 2025

Isolated to scattered TSRA are possible late this afternoon into
the evening across the Black Hills and southwest SD. Locally MVFR
cigs/vsbys will be possible with some of the stronger storms. The
storms should dissipate by 18/04Z. Otherwise VFR conds are
forecast through the terminal forecast period.

&&

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

$$

DISCUSSION/KEY MESSAGES...Woodward
AVIATION...Hintz