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000
FXUS63 KUNR 142331
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
531 PM MDT Sun Apr 14 2024

.KEY MESSAGES...

- Threat for strong to severe storms later Monday afternoon into
  Monday evening across much of the area.

- Locally heavy rain possible Monday night.

- Unsettled, windy, and gradually colder weather expected for the
  rest of the week.

&&

.DISCUSSION...(This Evening Through Sunday)
Issued at 217 PM MDT Sun Apr 14 2024

Western CONUS upper trough will cross the Rockies early this week
and support unsettled and much cooler conds as mean western CONUS
troughing persists. SE flow has revved up cross the region as
pressure falls ensue with the approaching storm system. Northern
BH eddy convergence has support a few puffs of cu with enough
conditional instability to support a light shower or two on the
adjacent plains. Otherwise, mainly quiet weather until later
tonight when a push of pos theta-e adv moves across the region.
Steep mid level lapse rates with moderate pos theta-e adv will
support elevated convection late tonight, shifting NE through
Monday morning. Some thunder will be possible toward central SD
with any activity given enhanced forcing from the LLJ and
sufficient elevated CAPE in place. SFC low will will deepen and
shift ENE across the Plains Monday. Staunch SE flow will advect a
tongue of 50s dewpoints air into the region, back as far west as
the BH, with adv level winds possible across scentral SD. Dry
trough will shift NE during the day forcing TS by late afternoon.
Although not as impressive a earlier model runs, enough bulk
shear and CAPE will be in place to support a few rotating updrafts
in the afternoon and early evening (esp in scentral SD where the
best deep layer shear will be), supporting a widow of severe
thunderstorms. Main threat will be large hail and strong winds. As
the system wraps up Monday night, main deformation snow will
develop over the western FA, supporting locally heavy rain there
with more scattered activity elsewhere. Cool front will shift
through the region Monday night, supporting the first round of
breezy winds. However, the strongest winds are expected Tues in
the lee of the BH, where low end warning levels still look
possible given terrain effect from the BH, with adv levels most
other places. Rain chances will end west to east Tues, with things
drying out some via dry NW winds. Secondary cold front will push
into the region Wed, bringing another chance for rain/snow showers
along with much cooler conds. Some light snow accums will be
possible Wed-Thur across NE WY and the BH as active unsettled flow
persists. Cool and unsettled conds will then continue thorough
the remainder of the week with periodic chances for rain/snow
showers.

&&

.AVIATION...(For the 00Z TAFS Through 00Z Monday Evening)
Issued At 527 PM MDT Sun Apr 14 2024

VFR conditions are expected through 18z Monday. Gusty
south/southeast winds will subside this evening as the boundary
layer decouples. LLWS will develop east of the Black Hills after
02z due to a 50kt low level jet. Gusty southerly winds will mix
out on the SD plains Monday. Isolated/scattered thunderstorms will
develop later Monday afternoon over the area with local IFR
conditions in/near the strongest storms, some of which may
contain hail and erratic gusty winds.

&&

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

$$

DISCUSSION/KEY MESSAGES...JC
AVIATION...Helgeson