349 
FXUS63 KUNR 021110
AFDUNR

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

.KEY MESSAGES...

-Unsettled conditions through the weekend with isolated to
 scattered showers/storms at times

-Warmer and drier next week

&&

.DISCUSSION...(Today Through Friday)
Issued at 146 AM MDT Sat Aug 2 2025

Semi-unsettled westerly flow will continue through this weekend 
with chances for showers and thunderstorms in parts of the region.
Flow will amplify next week, with drier and warmer SW flow 
becoming established, although weak passing waves will support 
isolated TS chances at times in the area. Lee side trough will 
shift east with warmer and drier conds today over the majority of 
the FA, esp over northeast WY where dewpoints will fall in the 40s
and even a few 30s. East of the trough/dryline in western SD, 
semi-humid conds will continue. Slow moving compact mcv/upper low 
will shift into the eastern part of SD today, with a few lingering
morning showers possible toward central SD, possibly lingering 
into early afternoon. Dry weather expected over the remainder of 
the FA most of the day. However, the next impulse will shift into 
the region late in the day, supporting chances for showers and 
storms as convection fires on the high terrain of WY and shifts 
east, possibly skirting the far SW in the late afternoon and early
evening. Another area of expected activity will be over eastern 
MT, with storms developing there in the late afternoon/early 
evening and possibly sagging into the FA this evening. Broad 
brushed low pops over most of the FA this evening as the weak 
impulse shifts east, with storms likely being driven by outflow 
boundaries and local effects, making it difficult to pinpoint 
exactly where storms will develop and propagate. Sufficient CAPE 
will be in place, however deep layer shear will again be lacking. 
Main threat with any stronger storms will be strong gusty winds 
given deeper BL mixing expected today and appreciable downdraft 
CAPE. Expect warmer highs today with mainly 80s expected. Any 
lingering storms will shift east and wane overnight. Sunday is 
trending drier with shortwave ridging expected. The best chance 
for any storms will be over the Black Hills given conditional 
instability in place with weak CIN. Hence, have the highest pops 
there and on the adjacent Plains to the east. Outside of the 
Hills, there really isn't a strong signal for convective forcing 
other than a sfc trough stalled over NW SD. Hence have cut pops 
and limited to 20 most other places. Lack of deep layer shear, and
marginal CAPE will support a low threat for severe weather, with 
gusty winds being the main threat. Digging western CONUS trough 
early next week will support warmer temps over the Northern Plains
and a drying trend, with the bulk of TS coverage expected to be 
more isolated. Expect some 90s to return Monday and Tues, with TS 
chances being driven by any passing impulses.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Sunday Morning)
Issued At 508 AM MDT Sat Aug 2 2025

Patchy fog will be possible this morning over far southwest SD, as
well as patchy MVFR cigs elsewhere. VFR conditions are then 
expected for the remainder of the day. The next chance for storms 
will be late this afternoon and evening, mainly across the western
half.

&&

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

$$

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