158
FXUS63 KUNR 280530
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1130 PM MDT Wed Aug 27 2025

.KEY MESSAGES...

- Temperatures around normal through the Weekend.

- Isolated to scattered showers possible this afternoon and
  Thursday.

- More widespread precipitation chances possible over the
  weekend.

&&

.DISCUSSION...(This Evening Through Wednesday)
Issued at 125 PM MDT Wed Aug 27 2025

Current Water Vapor and upper air models show upper trough over
the New England region, with northwest flow over the forecast area
as a narrow ridge sits over the lee side of the Rockies into the
northern plains. Surface analysis depicts a low over north central
WY with a frontal boundary stretching down into southeastern WY.
Temperatures currently sit in the 70s to mid 80s across the FA,
with radar showing some returns developing in northeastern WY near
the boundary.

Main forecast concern will be shower/storm chances today through
the weekend. Boundary axis shifts eastward, increasing storm
chances this afternoon and evening, mainly over northeast Wyoming
through the Black hills and southwestern SD where the better
forcing is progged. Some areas of modest CAPE in the 500-1000 j/Kg
range, however little to no shear observed and forecasted, so very
low chance of any severe storms today. Precipitation chances
continue Thursday, as wave traverses slowly across the northern
plains.

Messy overall pattern expected over the weekend, as the narrow
ridge flattens into northwest flow, with multiple shortwaves
moving over the northern plains. Better chance for more widespread
wetting rains Friday and Saturday. PWAT values increase to the
1-1.5 range as return moisture moves in.  Upper flow is not
strong, and will likely continue to limit any potential for
organized severe storms through the weekend. Chances for
shower/storms diminish later Sunday and Monday, as upper ridge
tries to strengthen over the western CONUS. May see a slight warm
up early next week as ridge tries to strengthen, but overall
expect temperatures to remain close to normal through the forecast
period.

&&

.AVIATION...(For the 06Z TAFS Through 06Z Thursday Night)
Issued At 1122 PM MDT Wed Aug 27 2025

Iso showers remain in northeast corner of WY. Could stick around
through night, limited PoPs to taf sites. Increasing shower and
storm coverage through Thursday beginning west of Black Hills as
early as 12z and expanding E through the afternoon and evening
hours. Local and brief MVFR/IFR conditions possible with heavier
precip, otherwise IFR through period. Winds var overnight
becoming more E to SE through the day Thursday.

&&

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

$$

DISCUSSION/KEY MESSAGES...Dye
AVIATION...Marlow