Denby, South Dakota Weather Forecast Discussion

598
FXUS63 KUNR 040519
AFDUNR
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1119 PM MDT Fri Oct 3 2025
.KEY MESSAGES...
- After a hot and dry Friday, weekend pattern shift expected
  Saturday and Sunday.
- Cold front Saturday will bring rain, gusty winds, and colder
  temperatures.
- Gradual warming trend early next week, with once again mostly
  dry conditions.
&&
.DISCUSSION...(This Evening Through Friday)
Issued at 202 PM MDT Fri Oct 3 2025
Current Water Vapor and upper air models show broad upper ridge
over the eastern CONUS, with the upper trough just entering the
Rockies region, and southwest flow over the forecast area.
Surface analysis shows a low over eastern Montana, with frontal
boundary stretching down into western WY and into UT. Winds
currently are mainly out of the southwest, with temperatures in
the mid 80s to mid 90s.
Hot and dry conditions will continue in the near short term, but
we will quickly see the pattern shift on Saturday, as the upper
trough shifts over the Rockies and into the plains. Associated
surface low and cold front will move into the area later Saturday.
Could see some precipitation out ahead of the boundary, however
main QPF chances look to be the latter half of Saturday through
Sunday morning. HREF probabilities show a strong signal for 0.5"
24hr/QPF or more over the northern half of the forecast area and
down into the Black Hills. Given the late day timing of the
front, can expect a large temperature range for highs Saturday,
with highs in northeast WY to NW SD in the low to mid 60s, while
south central SD may see near 90 again. Warmer temperatures along
with steep lapse rates could support isolated TS with a small
severe potential, mainly east and south of the Black Hills. The
Black hills will see low temperatures in the low 30s Sunday
morning, and CAA may allow for rain to mix with or change over to
snow in the higher elevations of the BH. Strong pressure rises
behind the front will also prompt gusty northwest winds that may
require wind advisory headlines Sunday, with GFS showing 4-6
mb/3hr press rises. While the best QPF chances diminish Sunday
morning, precip may linger into Monday morning on the back side of
the low.
Early next week the upper trough shifts eastward, with models
showing weak upper ridge attempting to build over the PAC NW. This
will result in a warming trend. The Euro and GFS both point
to a shortwave crossing the northern plains sometime mid-week,
though with different timing. Both models show scant moisture with
this disturbance, however it is still pretty far out. Will monitor
trends to see the degree of local effects.
&&
.AVIATION...(For the 06Z TAFS Through 06Z Saturday Night)
Issued At 1116 PM MDT Fri Oct 3 2025
A cold front will cross the area at this time...just nearing KRAP.
Winds behind the frontal boundary will shift to the NW and become
breezy Saturday morning. A storm system approaching the area
today will bring increasing chances for showers/isolated -TSRA
from west to east...and MVFR/IFR conditions Saturday afternoon
through the rest of the forecast period.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...None.
WY...None.
&&
$$
DISCUSSION/KEY MESSAGES...Dye
AVIATION...13
FIRE WEATHER...13

NWS UNR Office Area Forecast Discussion