079
FXUS63 KUNR 010349
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
949 PM MDT Mon Aug 31 2026

.KEY MESSAGES...

- Near-critical to critical fire weather conditions expected
  Wednesday through at least Friday.

- Cooler Tuesday with above average temperatures (10F+ above
  normal) for the latter half of the week.

&&

.UPDATE...
Issued at 945 PM MDT Mon Aug 31 2026

Going forecast in good shape. Water vapour loop depicted
shortwave over UT, which will slip northeast overnight into
Tuesday bringing modest 800-600mb theta-e advection and a slug of
moisture. Result will be a cluster of shra/TS through midday and
then isolated strong/severe thunderstorms over south-central SD
Tuesday afternoon. Temperatures will be tricky Tuesday given
precipitation/cloud cover, so stuck with guidance. Then, very warm
to hot and mostly dry into next weekend.

&&

.DISCUSSION...(This Evening Through Monday)
Issued at 100 PM MDT Mon Aug 31 2026

Water vapor imagery shows upper low centered over eastern
Saskatchewan and western Manitoba with southwest flow across the
western half of the country. Shortwave trough and mid- level
moisture plume is evident over the Four Corners region. Surface
low pressure is centered over southeastern Saskatchewan with a
cold front stretching from northern MN through western IA.

Cooler today (80s-90 on the plains with 70s to near 80 in the
Black Hills) and dry with elevated fire weather the main concern.
Water vapor imagery highlights upper level moisture pushing into
the southern forecast area ahead of the shortwave trough to our
southwest. This wave will bring showers and storms to the area
late tonight/early Tuesday morning through Tuesday afternoon.
While widespread severe weather is not expected, a few strong to
severe storms are possible across south-central SD into south-
eastern SD Tuesday.

Upper level ridge will build across the Northern Plains Wednesday
through the end of the week with much hotter and drier weather.
Highs will push into the 90s to near 100 by Friday (on the
plains). Stronger southerly winds will develop during this time,
resulting in near-critical to critical fire weather conditions
Wednesday through at least Friday.

&&

.AVIATION...(For the 06Z TAFS Through 06Z Tuesday Night)
Issued At 927 PM MDT Mon Aug 31 2026

A band of showers with embedded thunder will move through the area
after 01/09z, persisting through much of Tuesday as the
precipitation moves northeast. Isolated MVFR conditions may occur,
especially over south-central SD. Otherwise, VFR conditions will
prevail through the forecast period.

&&

.FIRE WEATHER...
Issued At 100 PM MDT Mon Aug 31 2026

Elevated fire weather conditions today across the area with
daytime RH falling into the teens, although winds will generally
remain below critical levels. Precipitation chances return for
southern into south-central SD late tonight into Tuesday ahead of
much warmer weather to end the week.

Temperatures will warm into the upper 80s to low 90s Wednesday with
even hotter temperatures Thursday and Friday as RH falls into the
teens; near single digit RH possible across portions of far SW South
Dakota into NE Wyoming Thursday and Friday where south-southwest
winds will gust 25 to 30 mph.

&&

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

$$

UPDATE...Helgeson
DISCUSSION...SE
AVIATION...Dye
FIRE WEATHER...SE