189
FXUS63 KUNR 181132
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
532 AM MDT Thu Jul 18 2024

.KEY MESSAGES...

- Near average temperatures with a daily chance of thunderstorms
  through the weekend. Isolated severe storms possible Friday

- Trending warmer and drier for the first half of next week with
  elevated fire weather conditions.

&&

.DISCUSSION...(Today Through Wednesday)
Issued at 210 AM MDT Thu Jul 18 2024

Current surface map places high pressure across the Upper Midwest
with weak return flow across the high plains. A few mid/high
clouds across the area with temperatures in the 60s on the
plains/50s for the Black Hills. Water vapor shows upper high
across the Intermountain West with shortwave over the Pacific
Northwest. For today, surface high slips southeast with weak
trough developing along the Rockies. Steep lapse rates will result
in a bit of buoyancy across the forecast area this afternoon and
evening. Overall, lack of forcing should limit thunderstorm
development this afternoon to higher terrain of eastern Wyoming
and the Black Hills. With MLCAPE around 1000J/KG and marginal
shear, an isolated severe storm is possible across the
central/southern Black Hills this afternoon/early evening.
Thunderstorm coverage will increase overnight with combination of
shortwave moving into eastern Montana and theta-e advection on
nose of low level jet. Thunderstorms continue through the day
Friday as shortwave moves through western South Dakota mid-day.
Sufficient buoyancy/shear for a few robust updrafts with a severe
wind/hail threat later tonight into Friday.

Upper ridge becomes more amplified over the weekend with
northerly flow aloft over the Plains. Embedded impulses will keep
small chances for thunderstorms in forecast each day. Early next
week, upper trof moves into Pacific northwest, nudging the ridge
into the Northern Plains. This will bring warmer/drier conditions
across the forecast area. With that, elevated fire weather
conditions are expected.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Friday Morning)
Issued At 532 AM MDT Thu Jul 18 2024

VFR conditions are generally expected today into tonight.
Isolated showers and thunderstorms are possible this afternoon and
tonight, especially from northeast WY to southwest SD. Showers
may become more widespread across the area later tonight.

&&

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

$$

DISCUSSION/KEY MESSAGES...7
AVIATION...26