071
FXUS63 KUNR 110745
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
145 AM MDT Tue Aug 11 2026

.KEY MESSAGES...

- Warmer through today, then becoming unsettled and cooler.

- Strong to severe storms possible this afternoon across western
  SD.

- Elevated to near critical fire weather conditions today across
  portions of northeast WY.

- Wildfire smoke is expected to linger much of the week, with
  thicker smoke at times across the western third

&&

.UPDATE...
Issued at 131 AM MDT Tue Aug 11 2026

Weak, isolated convection has popped up east of the Black Hills in
the last hour or so. SPC mesoanalysis depicts 3000-4000 J/kg
MUCAPE over much of western SD which will fuel isolated, elevated
convection through the next few hours. Have added low PoPs over
portions of the western SD plains to account for this. The
supercell in central SD that caused quite a bit of severe weather
this evening has weakened greatly and continues to move
southeastward. Some areas in south central SD may see some hail
and gusty winds but not anticipating any further severe weather
overnight.

Attention turns towards later today/this afternoon. CAMs continue
to show storms developing over northwestern SD into the Black
Hills after 21-22z (3-4 pm MDT) as corridor of 2500-3500 J/kg
MLCAPE develops over the area. Effective shear of 40-50KT and
forecast wind profiles supportive of supercell structure with
large to very large hail being the main hazards of concern (though
damaging wind gusts are also possible).


&&

.DISCUSSION...(This Evening Through Monday)
Issued at 1249 PM MDT Mon Aug 10 2026

Early this afternoon, we are still watching and waiting to see if
we can get some storms going. Thunderstorm chances are still
highly conditional and will depend on whether or not we can break
the cap. Yesterday, one storm was able to develop and as of this
writing, clouds are building over the central Black Hills. So it`s
possible.

For tonight, any storms that are able to develop, they will move
east through the evening. Overnight looks quiet with diminishing
winds and overnight lows in the 50s to 60s.

Tuesday looks similar to today, with highs mostly in the upper
80s to 90s. Zonal flow will keep the daily chances for afternoon
storms in place. SPC has placed a Slight (level 2 of 5) over the
central SD counties for Tuesday.

The SPC has also placed a Slight risk of severe weather on
Wednesday over SW SD. Modest westerly winds aloft will be over the
central High Plains Wednesday with a surface low developing near
the CO/KS border. Easterly surface winds north of the low over
Nebraska into southern South Dakota will maintain moisture and
instability into the area. Storms will form over the High Plains
and move eastward through the evening. Hail may occur initially,
with damaging gusts possible during the evening.

Unsettled pattern under zonal flow will give the area cooler
temps and daily chances for rain and storms for the second half of
the week.

&&

.AVIATION...(For the 06Z TAFS Through 06Z Tuesday Night)
Issued At 1019 PM MDT Mon Aug 10 2026

Some low clouds and associated MVFR/LCL IFR conditions may develop
over the eastern foothills of the Black Hills and portions of
the western SD plains after 09z this morning. These clouds may
impact the KRAP terminal though confidence too low at this time to
warrant mention in the TAF. These low clouds should dissipate
after 15z.

TSRA may develop over the Black Hills and northwestern SD after
18z this afternoon. Have kept the PROB30 group in for KRAP for
storms this afternoon and evening. These storms will push
east/southeast into the western SD plains through the evening
hours. LCL MVFR conditions, gusty and erratic winds, and hail may
be encountered with any storms.

&&

.FIRE WEATHER...
Issued At 1249 PM MDT Mon Aug 10 2026

Critical fire weather conditions are developing across
northeastern WY and far southwestern SD early this afternoon.
Critical fire weather conditions will last into the evening. A Red
Flag Warning is in effect for these areas.

Hot and dry weather with elevated fire weather conditions
(especially over northeastern WY) will continue through the mid
week. Cooler and unsettled weather moves into the region by
Wednesday and continues through the late week.

&&

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

$$

UPDATE...Wong
DISCUSSION...GS
AVIATION...Wong
FIRE WEATHER...GS