764
FXUS63 KUNR 190751
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
151 AM MDT Tue Aug 19 2025

.KEY MESSAGES...

- An isolated storm or two can`t be ruled out over the Black Hills
  today

- Drier and warmer conditions expected Tuesday and Wednesday.

- More seasonable temperatures and unsettled conditions return
  late in the week.

&&

.DISCUSSION...(Today Through Monday)
Issued at 150 AM MDT Tue Aug 19 2025

Current water vapor imagery and upper air analysis depicts 500hpa
ridge axis centered over the Rockies. At the sfc, broad high
pressure sits centered over eastern CO. Aside from a few mid level
clouds over northeastern WY, skies over the CWA are mostly clear.
Temperatures are in the mid 60s to mid 70s with light and
variable winds.

500hpa ridge will remain overhead today resulting in warmer and
drier conditions. Low level upslope flow will continue to bring
moisture into the western SD plains with afternoon dewpoints in
the 50s to 60s. Steep lapse rates will support SB CAPE values of
1000+ J/kg over the western SD plains by this afternoon. However,
rising heights and warming 700hpa temps should keep conditions
capped. An isolated storm or two can`t be entirely ruled out over
the eastern slopes of the Black Hills where upslope flow and
terrain induced convergence may be enough to overcome the cap.

Upper level ridge will take on a more positive tilt through the
mid week with low level thermal ridge developing over the Northern
Plains. Wednesday should be the hottest day of the week as the
low thermal ridge sets up over the CWA with highs in the 90s to
low 100s. Not anticipating any need for heat headlines for
Wednesday as drier air moves into the region. Thursday won`t be
quite as hot as Wednesday thanks to a northern stream trof grazing
the region and flattening out the ridge. Attendant cool front
will sweep across the region late Thursday which will bring
chances for showers/storms back to the region Thursday night. As
the trof strengthens and digs into the eastern CONUS through the
weekend, northwest flow will establish itself over the region.
This translates to relatively cooler weather with daily chances
for precip through the weekend.

&&

.AVIATION...(For the 06Z TAFS Through 06Z Tuesday Night)
Issued At 1132 PM MDT Mon Aug 18 2025

VFR conditions are expected through much of the period. Isolated
storms are again possible late Tuesday afternoon.

&&

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

$$

DISCUSSION/KEY MESSAGES...Wong
AVIATION...13