996
FXUS63 KUNR 051555
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
955 AM MDT Fri Jul 5 2024

.KEY MESSAGES...

- Milder through Sunday with chances for thunderstorms
- Hot/dry weather develops next week

&&

.DISCUSSION...(Today Through Thursday)
Issued at 109 AM MDT Fri Jul 5 2024

07z surface analysis had weak high over the CWA. Water vapour had
upper low spinning over MN with weak shortwave over central WY,
which is creating a small patch of showers/TS just southwest of
the CWA per regional radar loop. Western CONUS upper ridge
continues with northwest flow over southwest Canada into the
northern Plains - our main weather maker through the weekend.

Today through Sunday, a series of weak shortwaves will slide
through the northern Plains. The first wave arrives late this
afternoon/evening, second later Saturday, and third early Sunday.
Buoyancy/shear today and Sunday not conducive to active
convection. But for Saturday, HREF suggests 0.5-1KJ/kg SBCAPE with
35-45kt 0-6km bulk shear over southern SD may support isolated
severe thunderstorms. Have painted slight chance/chance pops to
reflect thoughts. Temperatures will be near guidance.

Next week, high confidence that western CONUS upper/thermal ridge
builds from the Rockies into the plains. Result will be
significantly warmer/drier and eventually hot temperatures.
Probability of 90F+ highs >75% by the end of the week for most of
the CWA. Some 100F readings expected.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Saturday)
Issued At 952 AM MDT Fri Jul 5 2024

Scattered TSRA/SHRA with associated LCL MVFR conditions are
expected to develop through this afternoon and evening. Otherwise,
VFR conditions expected through the TAF period.

&&

.FIRE WEATHER...
Issued At 109 AM MDT Fri Jul 5 2024

Confidence is high that a pattern change next week will result in
increasingly hot weather. Minimum afternoon relative humidities
in the 20s will be common by Wednesday, with some teens over
northeastern WY/far southwest SD. Elevated fire weather conditions
are expected.

&&

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

$$

DISCUSSION/KEY MESSAGES...Helgeson
AVIATION...Wong
FIRE WEATHER...Helgeson