330
FXUS63 KUNR 302303
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
503 PM MDT Mon Jun 30 2025

.KEY MESSAGES...

- Hot Tuesday through Thursday, with cooler, more seasonable
  temperatures for the holiday weekend.

- Isolated thunderstorms Tuesday and Wednesday, scattered to
  numerous storms late Thursday into the Independence Day weekend.

&&

.DISCUSSION...(This Evening Through Monday)
Issued at 240 PM MDT Mon Jun 30 2025

Latest Water vapor imagery has a sharp upper trof sliding across the
north central CONUS, with the axis exiting the eastern Dakotas while
a broad ridge builds over the western CONUS. At the surface, high
pressure is centered over the area. Temperatures are in the upper
70s to low 80s, with northwest winds across the South Dakota
Plains.

For tonight, subsidence will prevail across the forecast area as a
subtle shortwave crosses the region toward daybreak. With the lack
of appreciable moisture, just may see a few clouds if anything.

Sunny and warm for Tuesday as the surface high slides east allowing
for moist southerly flow to return to the forecast area. Dew point
temperatures in the 50s and SBCAPE of 500 to 1000 J/kg may be enough
for a shower or storm to to develop over the Blacks Hills or the
higher terrain of northeastern Wyoming, as the large scale
subsidence begins to depart. Therefore have left slight chances in
the forecast for this area. Later in the evening and during the
overnight, 35-40kt low-level jet may support convective initiation
across south central South Dakota.

The upper ridge shifts eastward on Wednesday and Thursday, with the
thermal axis centered over the forecast area Thursday morning. This
will result in hot temperatures across the CWA. Many locations
across the western SD Plains will reach triple digits Thursday
afternoon. As for precipitation chances, the best environment
Wednesday afternoon will be over northwestern portion of the
forecast area with steep lapse rates and dewpoints in the upper 50s
to low 60s. By Thursday afternoon and evening the ridge axis will be
east of the area. Falling heights, a frontal boundary sagging
southward from Montana/North Dakota, and Q-vector convergence will
all likely lead to some convection. Depending on timing of waves
embedded in the flow, could see the potential for severe storms
Thursday through the holiday weekend. This is supported by the CIPS
and to a lesser extend the CSU-MLP. Temperatures through the holiday
weekend will likely remain near to slightly above average.

&&

.AVIATION...(For the 00Z TAFS Through 00Z Tuesday Evening)
Issued At 502 PM MDT Mon Jun 30 2025

VFR conditions will prevail through the period. Isolated
thunderstorms may develop later Tuesday afternoon over western
SD.

&&

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

$$

DISCUSSION/KEY MESSAGES...Smith
AVIATION...Helgeson