159
FXUS63 KUNR 041111
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
511 AM MDT Mon Aug 4 2025

.KEY MESSAGES...

-Seasonally warm with isolated to scattered thunderstorms at
 times

-Severe storms possible this afternoon from the Black Hills
 southeast into Nebraska

&&

.DISCUSSION...(Today Through Sunday)
Issued at 116 AM MDT Mon Aug 4 2025

Northeast Pac upper trough will force a ridge east into the
Plains, as active northern periphery flow continues. Main storm
track will slowly shift north the next couple days, with the bulk
of precip chances. However, thunderstorms will impact the FA today
and Tues, with severe storms possible both days. Pos theta-e adv
ongoing aloft, supporting a cluster of TS over northeast WY. This
activity may persist into SD before waning later this morning. Lee
side trough will setup over the region, with increasing moist SE
flow today. Appreciable CAPE (1500-2500 J/KG) and increasing bulk
layer shear will be in place by this afternoon, supporting a good
setup for storms to initiate on the northern Black Hills. With
bulk shear values exceeding 40 knots this afternoon, the potential
for storms to organize into supercells will be pretty good.
Current progs suggest storms to initiate over the northern BH,
turn right, then likely organizing into cluster of storms as they
progress southeast. Main threat with these potential storms would
be large hail, possibly 2 inches or larger, damaging winds, and
heavy rain. Another round of nocturnal storms will be possible
once again late tonight across northwest SD as pos theta-e adv
develops ahead of the next shortwave coupled with a LLJ. Sfc
trough will shift east Tues with more storms possible in the
afternoon, mainly across northwest SD and the Black Hills. Any
storms that do develop on Tues could be strong to severe with
appreciable CAPE, although deep layer shear looks marginal,
possibly limiting upscale growth. Expect highs through Wed into
the 80s and 90s most places. Upper ridge will build over the area
Wed-Thur, peaking Thur when the thermal ridge passes over the
region, supporting the hottest day this week. Expect widespread
90s Thur, with low 100s likely on parts of the Plains. Given
lingering ll moisture, expect apparent T`s will be close enough to
warrant excessive heat products, mainly across scentral SD. Drier
weather also expected Wed and Thur as the storm track shifts
north. Cold front moves through at the end of the week, with a
good chance of storms by Friday and cooler temps for the weekend.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Tuesday Morning)
Issued At 508 AM MDT Mon Aug 4 2025

Isolated TS from northeast WY into scentral SD will dissipate
this morning. Otherwise, scattered to Isolated storms are possible
again this afternoon and evening, mainly from the Black Hills
southeast. Some storms may be severe with large hail and damaging
winds. Otherwise, VFR conditions expected through the TAF period.

&&

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

$$

DISCUSSION/KEY MESSAGES...JC
AVIATION...JC