Minne-Ka-Tah, South Dakota Weather Forecast Discussion

709
FXUS63 KUNR 251718
AFDUNR
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1118 AM MDT Thu Sep 25 2025
.KEY MESSAGES...
- Dry conditions and above average temperatures into next week
- Gusty northerly winds behind cool front Friday
- Elevated fire weather conditions at times
&&
.DISCUSSION...(Today Through Wednesday)
Issued at 1256 AM MDT Thu Sep 25 2025
06z surface analysis had weak trough from northern ND into MT.
Water vapour loop showed upper ridge over Rockies poking into the
northern Plains with upper trough approaching BC. Plenty of stars
across the CWA per nighttime physics RGB. BC upper trough the main
forecast concern.
Today/tonight, weak trough brushes the CWA with the main effect
being wind shifts. Thermal ridge will support highs in the 80s on
the plains with 70s for the Black Hills. Went a skosh above
guidance per abundant solar insolation/dry air.
Friday, upper ridge flattens courtesy of BC upper trough zipping
across the northern plains. 2-4mb/3hr pressure rises behind
advancing dry cool front will combine with well-mixed boundary
layer (25-35kt mean per Bufkit soundings) to produce gusty winds
at times. A few spots may gust near 40mph (20% chance HREF/NBM).
Temperatures will be slightly above guidance again given dry air,
especially ahead of the cool front over southern SD.
Saturday through early next week, upper ridge becomes
reestablished over the plains as it shifts east in response to
upper trough developing over the northwest CONUS. Eventually,
southwest flow aloft develops over the northern plains, but
moisture will be scant until possibly the end of next week when
low pops appear. Temperatures will be 5-12F above normal on
average.
&&
.AVIATION...(For the 18Z TAFS Through 18Z Friday)
Issued At 1116 AM MDT Thu Sep 25 2025
VFR conditions are expected through the forecast period. Winds
will generally be variable at RAP until a cold front moves through
towards the end of the period. At GCC, winds are expected to
shift from southerly this evening to northerly as the
aformentioned cold front move through tomorrow morning.
&&
.FIRE WEATHER...
Issued At 1256 AM MDT Thu Sep 25 2025
Sustained dry weather with above normal temperatures will bring
elevated fire weather conditions to the area over the next 7 days.
MinRH will drop to the teens over northeastern WY this afternoon
and over northeastern WY/southwestern SD Friday. MinRH in the 20s
will be common elsewhere through the forecast period. Breezy winds
will occur at times, but particularly Friday with a dry cool
front passage may bring wind gusts near 40mph on the northwest SD
plains.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...None.
WY...None.
&&
$$
DISCUSSION/KEY MESSAGES...Helgeson
AVIATION...Bunker
FIRE WEATHER...Helgeson

NWS UNR Office Area Forecast Discussion