952
FXUS63 KUNR 182313
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
513 PM MDT Fri Jul 18 2025

.KEY MESSAGES...

- Daily chances for thunderstorms through early next week.

- Temperatures around or above normal expected through the
  forecast period.

&&

.DISCUSSION...(This Evening Through Friday)
Issued at 149 PM MDT Fri Jul 18 2025

Current surface analysis shows low pressure centered over central
SD, with frontal boundary running through south central SD into
western NE and central WY. Upper models show zonal flow aloft.
Temperatures currently sit in the upper 70s and 80s with
relatively light northwest to northeast winds behind the boundary.

This afternoon, boundary wraps up into northeastern WY, providing
an area of forcing amid a strong cap today. If storms are able to
fire up, expected over northeastern WY down into southwestern SD
late this afternoon or early evening. Modest shear but plenty of
CAPE could support an organized severe storm or two if initiation
is able to occur. Likely wont see any development outside of the
immediate frontal zone. Threat today would be large hail and
strong winds. Shortwave moving across the FA will support
elevated showers/storms overnight, however no organized severe is
expected.

Models show zonal to quasi-zonal flow persisting through the
forecast period, with disturbances marking daily chances for
storms over the area. While widespread severe is not expected,
localized strong storms will remain a possibility over the
weekend. Shortwave moves though at a better time Saturday to
support isolated severe storm potential, coupled with 1000-2000
j/Kg ML CAPE and 30-40 kt 0-6km shear, if able to overcome the
cap. May see potential for terrain driven upslope Black Hills
development moving off into the plains. Similar set up for Sunday
will support more isolated storm potential. Longer range models
show little change in the overall pattern, keeping temperatures
relatively steady, with daily (but limited) convective activity.

&&

.AVIATION...(For the 00Z TAFS Through 00Z Saturday Evening)
Issued At 511 PM MDT Fri Jul 18 2025

Scattered showers and isolated thunderstorms can be expected
across the entire area late tonight into Sat morning. Over south
central South Dakota, areas of IFR vsby/cigs are likely after 06Z
Saturday due to low clouds/fog, which will persist through Sat
morning. More showers and storms expected across the area late
Sat afternoon and evening.

&&

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

$$

DISCUSSION/KEY MESSAGES...Dye
AVIATION...JC