605
FXUS63 KUNR 251059
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
459 AM MDT Tue Jun 25 2024

.KEY MESSAGES...

- Warm with isolated thunderstorms today and Wednesday.

- Better chance of thunderstorms on Thursday with increasing
  severe thunderstorm potential

&&

.DISCUSSION...(Today Through Monday)
Issued at 225 AM MDT Tue Jun 25 2024

Current surface map places weak high across the western Dakotas.
East-west line of thunderstorms continue is located from north of
the Black Hills into central South Dakota in area of 750-600mb
theta-e advection. This thunderstorm activity lingers through
early morning with a gradual decrease in coverage and intensity.
Later this afternoon/evening, shortwave slides through eastern
Montana into North Dakota. Residual low level moisture and steep
lapse rates across the area, with MLCAPE around 2000J/KG. Some
question as to thunderstorm coverage as best forcing remains north
of the forecast area and robust cap in place, especially east of
the Black Hills. CAMs pop up a few storms this afternoon/evening,
with higher probabilities around the Black Hills and along weak
front sliding through. Sufficient shear to support severe hail
threat.

Surface high drops across the area tonight/early Wednesday,
with drier boundary layer across the forecast area, shunting best
buoyancy south of the forecast area. Impulse tracking through
flat ridge may be enough to bring a few high based storms across
northeastern Wyoming/Black Hills area Wednesday afternoon.
Thunderstorm coverage increases Wednesday evening/overnight on
nose of level jet/theta-e advection.

Strong shortwave moves through the northern Rockies into the
Plains late Thursday with surface low/cold traversing the western
Dakotas. Buoyancy/shear favorable for all modes of severe weather
Thursday afternoon/evening. Temperatures cool down for
Friday/Saturday with lingering shower/thunderstorm activity.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Wednesday Morning)
Issued At 453 AM MDT Tue Jun 25 2024

Scattered showers over northwestern SD early this morning will
move off to the east by 15Z this morning. Isolated thunderstorms
may develop around the Black Hills after 19Z this afternoon and
over the western South Dakota plains after 21Z. Severe storms are
possible. Any storms are expected to end by 03Z this evening. VFR
conditions will prevail through the period.

&&

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

$$

DISCUSSION/KEY MESSAGES...7
AVIATION...10