042
FXUS63 KUNR 121746
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1146 AM MDT Tue May 12 2026

.KEY MESSAGES...

-Warm and windy this week with critical to near critical fire
 weather conditions the rest of the week

-Cooler late this weekend/early next week with some low chances
 for showers

&&

.DISCUSSION...(This Afternoon Through Monday)
Issued at 1142 AM MDT Tue May 12 2026

Western CONUS ridge will remain in place most of this week,
supporting warm and dry weather. Ridge topping impulses will
support weak cool fronts at times, with little to no precip with
each system. Breezy NW winds today behind the Great lakes upper
trough. Winds will gradually subside through the day. The next
upper trough will move into the Pac NW and will support a
deepening lee-side trough. This will allow SE winds to increase
Wed with gusts over 40 mph expected across NW SD at times.
Associated frontside impulse will shift east into NE WY later in
the afternoon and evening. Sufficient LL moisture should be in
place for isolated high based showers/TS. If convection does
develop, gusty winds would be expected per inverted-V profiles.
Convection chances will shift NE overnight. Did add some low pops.
Sfc trough will shift through the FA Wed night into Thur morning,
supporting gusty NW winds. Breezy winds can expected Thur, esp
over NW SD where adv level winds look possible. Breezy NW winds
will continue into Friday as another weak impulse advects through
westerly flow on the south side of the deeper southern Canadian
upper trough. Deeper upper trough will move into the Rockies this
weekend, leading to much cooler temps by Sunday as well as
slightly better (albeit still low) chances for showers into early
next week. Expect highs in the 50s and 60s most places Sunday and
Monday before things start to warm back up Tues. Models are
indicating that we may see better chances for rain later in the
week as Gulf moisture shifts north ahead of a Rockies trough.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Wednesday)
Issued At 1144 AM MDT Tue May 12 2026

VFR conditions are expected through the TAF period. Breezy
northwest winds will diminish late this afternoon into the
evening.  Looking ahead, breezy southeast winds are expected
Wednesday amidst otherwise continued VFR conditions during the
day.

&&

.FIRE WEATHER...
Issued At 1142 AM MDT Tue May 12 2026

Warm, dry and, windy conds with receptive fuels will continue to
support critical to near critical conds to most of western SD
through the end of the week. A fire weather watch has been issued
for much of western SD Wed through Thur, with a long duration of
critical fire weather conditions expected. Breezy SE winds will
develop Wed ahead of a trough of low pressure. Very dry conds,
with RH`s expected to fall to as low as 10 percent both Wed and
Thur afternoon (possibly Friday as well). The trough will move
through Wed evening and support gusty NW winds, with poor
overnight recovery. Gusty NW winds will continue Thur with
continued very dry profiles. Dry and breezy through Sat, with
potential extension of any fire headlines in SW SD. Cooler with
shower chances early next week, leading to a break in fire weather
concerns.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...Fire Weather Watch from Wednesday afternoon through Thursday
     evening for SDZ322>327-329-331>333.
WY...&&

$$

DISCUSSION/KEY MESSAGES...JC
AVIATION...Dye
FIRE WEATHER...JC