230
FXUS63 KUNR 010024
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
624 PM MDT Sun Jun 30 2024

.KEY MESSAGES...

- Chance for isolated storms this afternoon with the possibility
  of a strong to severe storm or two in northeastern WY. There
  are elevated fire weather concerns for northeastern Wyoming as
  well.

- Chance for storms on Monday with strong to severe storms
  possible, especially towards central SD.

- Unsettled weather will continue through the week with near daily
  chances for showers/storms.

&&

.DISCUSSION...(This Evening Through Sunday)
Issued at 155 PM MDT Sun Jun 30 2024

Current wv imagery depicts upper ridge over the Rockies/northern
plains. A plume of very dry air extends from southern Cal
northeastward into Wyoming. The dry air at the low to mid levels
is contributing to a strong cap which will inhibit convection this
afternoon across much of the area. Despite this dry air, isolated
high based storms have managed to develop along the dryline in
WY. These storms are currently moving eastward into Campbell
County. 30-45kts of effective shear over northeastern WY will lend
to a marginal severe threat with these storms. Inverted-V
profiles indicate that these storms will be capable of putting out
strong wind gusts. With the the deep layer of dry air, it`s
questionable if precip will be able to reach the ground. Dry
conditions (RHs have dropped to 15 to 30% across portions of
northeastern WY), hot temperatures of 80 to 90 degrees, and breezy
winds have contributed to some elevated fire weather conditions
across northeastern WY. Convection will make its way into far
western SD by the evening hours, though strength and coverage will
be limited due to the strong cap in place over western SD.

The main trough with attendant front will cross the region
Monday, bringing chances for storms to the region once more.
Strong southerly low level flow will advect ample GOMEX moisture
into the northern plains with sfc Tds expected to reach into the
mid-50s to upper-60s. Fcst soundings indicate deep layer moisture
which will lend to the severe threat as storms won`t struggle as
much as they will today. Short term models depict corridor of
1500-2500 J/kg MUCAPE across the eastern half of our CWA, towards
central SD. MUCAPE across western SD into northeastern WY will be
less but still a decent amount with values of 500-1500 J/kg. 50-60
kt of 0-6km shear will be sufficient for rotating updrafts. Large
hail and damaging winds will be the main hazards though there is
also a low tornado threat.

Upper trough will move east by Tuesday with quasi-zonal and
unsettled flow setting up over the region by Wednesday.
Temperatures through the mid week will be warm but not overly hot
with highs in the 70s to 80s. Disturbances along the flow will
contribute to daily chances for showers/storms. Another
wave/developing upper low swings through the area Thursday
bringing cooler temps and stormy weather for the 4th of July.

&&

.AVIATION...(For the 00Z TAFS Through 00Z Monday Evening)
Issued At 602 PM MDT Sun Jun 30 2024

Isolated showers and thunderstorms are possible this evening,
especially across NE WY and far western SD. Gusty, erratic winds
and MVFR conditions can be expected near any stronger storms.
Otherwise, VFR conditions will prevail.

&&

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

$$

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