289
FXUS63 KUNR 061722
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1122 AM MDT Sat Jul 6 2024

.KEY MESSAGES...

- Thunderstorm chances continue through Sunday afternoon
- Hot/dry weather develops next week
- Elevated fire weather conditions develop next week

&&

.DISCUSSION...(Today Through Friday)
Issued at 143 AM MDT Sat Jul 6 2024

07z surface analysis had a weak surface trough from eastern ND
into southeastern WY, which was a reflection of shortwave spinning
over east-central MT per water vapour loop. Regional radar loop
show isolated/scattered showers/TS pinwheeling across the CWA
tapping into 250-500J/kg MUCAPE. Western CONUS upper ridge remains
in place with next upstream shortwave noted over southern BC,
which will impact sensible weather later today.

Today/tonight, first shortwave will exit early this morning with
subsidence behind it resulting in a drier period this morning.
Secondary shortwave drops in this evening. Ahead of it, weak
buoyancy/shear expected except for south-central SD where 0.5-
1KJ/kg SBCAPE may develop with increasing shear. Timing of
secondary shortwave not ideal and CAMS have most updraft/helicity
tracks in NE. While isolated strong/severe thunderstorm cannot be
ruled out, setup marginal at best. Expect isolated/scattered
thunderstorms over the rest of the CWA this afternoon/tonight.
Temperatures will be near guidance.

Sunday, shortwave moves through under weak buoyancy/shear regime.
CAMS depict popcorn convection. Temperatures will be near
guidance.

Next week, high confidence that western CONUS upper/thermal ridge
expands into the northern Plains. The result will be drier and
increasingly hot weather. High probability of 90F+ MaxT for the
end of the week with 100F readings within reach.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Sunday)
Issued At 1118 AM MDT Sat Jul 6 2024

Isolated to scattered TSRA/SHRA will develop this afternoon and
move eastward through the area tonight. Otherwise, VFR conditions
are expected.

&&

.FIRE WEATHER...
Issued At 143 AM MDT Sat Jul 6 2024

Confidence is high that a pattern change next week will result in
increasingly hot weather. Minimum afternoon relative humidities
will dip into the teens and 20s, especially across northeastern WY
and far southwestern SD. Elevated fire weather conditions are
expected.

&&

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

$$

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