804
FXUS63 KUNR 101112
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
512 AM MDT Mon Jun 10 2024

.KEY MESSAGES...

- Severe weather is likely today with the primary hazards being locally
  heavy rainfall, large hail, damaging winds, and an isolated
  tornado threat.

- Near to above average temperatures with near daily chances for showers
  and storms through the end of the week.

&&

.DISCUSSION...(Today Through Sunday)
Issued at 232 AM MDT Mon Jun 10 2024

Current upper air analysis depicts upper level ridge over the
region with weak shortwave over WY/MT. Some convection associated
with the wave has developed over western ND and portions of NE WY.
This wave will move through the CWA this morning with chances for
showers and thunderstorms through the early morning hours. The
stronger wave responsible for our severe weather threat this
afternoon is currently over eastern OR/western ID.

This upper level wave will move through the region this afternoon
with attendant frontal boundary stretching from CO into WY/SD.
Vigorous southerly flow/LLJ will advect ample moisture into the
region with sfc dewpoints reaching into the 50s to 60s by early
afternoon. Front will reach northeastern WY by noon/early
afternoon with ML CAPE in NE WY reaching into the 1000-2000 J/kg
range. A few scattered showers/storms may begin developing around
this time with 0-6km bulk shear of 30-40kt supportive of rotating
updrafts. The front will cross into western SD as the afternoon
progresses with thunderstorms increasing in coverage as ML CAPE
values across western SD will reach 1500-2500 J/kg with 0-6km bulk
shear ranging from 30-45kt. This line of storms will cross
through the CWA through this afternoon into this evening with the
severe threat largely over by around 10 pm MDT. As stated, shear
will be supportive of rotating updrafts. Mid-level lapse rates of
around 6-8 C/km and MU CAPE of 1500-2500 J/kg and inverted V
profile are supportive of large hail and damaging wind gusts. An
isolated brief tornado or two can`t be ruled out. Another threat
for this afternoon will be locally heavy rainfall as PWAT values
of 1 to 1.4" (150-175% of normal) advect into the region.

Weak ridging builds into the region tomorrow resulting in a dry
and seasonably warm day, the ridge flattens out by Wednesday and
we`re put under mostly zonal flow through Friday before another
weak ridge builds into the region. A few disturbances riding along
the flow will result in periodic, near daily chances for
thunderstorms after Tuesday. In terms of temperatures, we will
warm up through the week with highs generally near to just above
average. Wednesday looks to be the warmest day of the week with
highs reaching the upper 80s with south central SD potentially
seeing highs in the low 90s. Temps cool off slightly but remain
near to slightly above average through the end of the week.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Tuesday Morning)
Issued At 508 AM MDT Mon Jun 10 2024

Local MVFR cigs over the Black Hills will dissipate by mid-
morning. A few high based showers/storms will continue this
morning but mainly VFR conditions will prevail. By early
afternoon, a cold front will move into the region, resulting in
strong to severe thunderstorms developing by early afternoon over
northeast WY and far western SD, then spreading eastward across
western SD into central SD this afternoon and early evening. IFR
conditions likely in stronger storms along with large hail and
damaging winds.

&&

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

$$

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