809
FXUS63 KUNR 071050
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
450 AM MDT Mon Jul 7 2025

.KEY MESSAGES...

- Scattered storms will continue across northeastern WY into
  western SD early this morning. While a strong storm or two is
  possible, overall severe threat is low this morning.

- Scattered strong to severe storms are possible today near the
  Black Hills and across southwestern/south central SD.

- Hotter and drier Tuesday into Wednesday.

- Unsettled conditions and severe weather potential return for
  Thursday and Friday

&&

.DISCUSSION...(Today Through Sunday)
Issued at 338 AM MDT Mon Jul 7 2025

Elevated convection is ongoing across northeastern WY into the
Black Hills. A few updrafts have pulsed up, feeding off of 1000
J/kg MUCAPE. Effective shear is marginal, with SPC mesoanalysis
depicting 20-25kt effective bulk shear over northeastern WY. The
stronger storms this morning will be capable of small hail and
gusty winds, but overall severe threat is low at this time.

Midlevel trof moves across the Northern Plains today, bringing
another round of severe weather to the region. Strong low to
midlevel frontogenesis progged to travel southeastward through the
region this morning into this afternoon. Moisture transport from
southerly flow ahead of the front and steepening lapse rates will
support a moderately to very unstable environment across much of
western SD by 18z (06z NAM ML CAPE values progged to exceed 2000
J/kg). 35-45kt bulk shear will support organized convection and
rotating updrafts. The main questions for today are the timing of
the front and how this morning`s convection will impact convection
later in the day. Outflow from the storms this morning may wash
out the better buoyancy and keep it further to the south, and the
front may move through too quickly/early for the environment ahead
of it to recover from this morning`s convection. This would limit
severe potential for most areas except for far southwestern into
south central SD where the front isn`t progged to move through
until the afternoon hours. 06z HRRR keeps convection out most of
western SD with a few discrete cells over the Black
Hills/southwestern SD and across south central SD. The 06z NAMNST
is a little more aggressive with convection, having the
environment ahead of the front recover quicker and depicts the
morning convection coalescing into an MCS later this morning and
tracking eastward across Butte and Meade Counties. It also shows
convection forming later this afternoon across southwestern into
south central SD. Right now it`s still looking like the best
chances for severe weather today will be across southwestern into
south central SD. Main concerns will be large hail and damaging
winds, though an isolated tornado can`t be ruled out this
afternoon across south central SD.

As the trof moves through, deep Q-vector divergence overspreads
the region with rising heights into Tuesday. This should limit
convection Tuesday as upper level ridging builds into the region.
Temperatures Tuesday afternoon will climb into the upper 80s to
90s as low level thermal ridge develops. Even hotter temperatures
expected Wednesday as upper ridge remains in place, highs will
easily reach the mid to upper 90s with the potential for some
spots to reach the triple digit mark. In terms of thunderstorm
risk for Wednesday, subtle shortwaves riding along the ridge could
support isolated storms. Stronger shortwave moves through on
Thursday which will bring the next chances for widerspread
thunderstorms (and potentially severe weather) to the CWA. Trough
digs into the Northern Plains by Friday and brings milder
temperatures to the CWA for the start of the weekend.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Tuesday Morning)
Issued At 441 AM MDT Mon Jul 7 2025

Scattered TSRA are ongoing this morning across northeastern WY
into western SD, these storms will move out of the region through
the morning hours. Patchy MVFR CIGS may develop across
northeastern WY into southwestern SD this morning. Another round
of storms will be possible in the afternoon, especially across
southwestern into south central SD. Brief MVFR conditions and
gusty winds will be possible near any storm.

&&

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

$$

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