000
FXUS63 KUNR 022237
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
437 PM MDT Sat Aug 2 2025

.KEY MESSAGES...

- Isolated to scattered storms for the remainder of the weekend.

- Dry and seasonable temperatures expected for much of next week.

&&

.DISCUSSION...(This Evening Through Saturday)
Issued at 131 PM MDT Sat Aug 2 2025

Current regional radar analysis shows leftover MCV located over
north central SD/south central ND. This feature is still creating
a few remnant showers east of the CWA. Associated 500hpa shortwave
is also located in the same area and is forecast to slowly move
ENE into eastern ND/western MN through the next 24 hours leaving
quasi-zonal flow over the northern plains. Surface dewpoints vary
from the low 40s to low 50s across the western CWA to the upper
50s to lower 60s across the eastern CWA.

The 1st sticking point is convective chances overnight as there is
some disagreement among the models. While there is some 700hpa
theta-e forcing along the NE border this evening (03z-06z time
frame), HREF and NBM probabilities of seeing thunder, or 40 dBZ or
greater, are generally 20% or less. However the HRRR seems to be
rather bullish in developing something along the NE/SD border
during this time along the nose of the aforementioned forcing. The
probabilities of seeing 0.01-0.10 of rain vary from 10% to 20%
across our far southeastern counties. Additionally there is
another 500hpa wave currently sliding into NW Wyoming, southern MT
that could spark of some late afternoon/evening TS in the central
sections of MT/WY that will drift into our WY counties this
evening. Shear is rather meh so not really looking for anything
severe to develop. In fact, probabilities of 40dBZ being reached
are about the same as in the south central part of SD. Will most
likely keep along the same lines as previous fcst with broad
brushed minor pops in overnight.

Sunday for the most part looks to be a quiet day except for the
probabilities of TS developing over the Black Hills. The question
will be how long will they survive coming off of the higher
terrain? ML CAPE by 21Z Sunday is in the area of 1500-2000 J/kg
with CIN minimized across the higher elevations. Another area of
concern is with the rather coolish 700hpa temps for this time of
year. With temps AOA 8 degrees C...thinking that forecast highs in
the mid 80s will be sufficient for convective temps. While
probabilities will be low, they will be non-zero.

500hpa ridge axis moves into and through the CWA in the Monday-
Tuesday time frame, with 850hpa temps warming as well. This should
allow temps to climb into the 90s for the first half of the week
across the area. With SW flow aloft, thunder chances will depend
on upper waves passing through in the flow.

&&

.AVIATION...(For the 00Z TAFS Through 00Z Sunday Evening)
Issued At 432 PM MDT Sat Aug 2 2025

Isolated storms are possible over the Black Hills, portions of
northeastern WY, and south central SD this evening. Chances for
storms will decrease after midnight. Otherwise, VFR conditions
expected for the TAF period.

&&

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

$$

DISCUSSION/KEY MESSAGES...Hintz
AVIATION...Wong