Deerfield, South Dakota Weather Forecast Discussion

841
FXUS63 KUNR 011948
AFDUNR
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
148 PM MDT Wed Oct 1 2025
.KEY MESSAGES...
- Well above normal temperatures and elevated fire weather
  conditions thorugh Friday.
- Pattern changes over the weekend to more seasonable temperatures
  and increasing chances for precipitation.
&&
.DISCUSSION...(This Evening Through Wednesday)
Issued at 116 PM MDT Wed Oct 1 2025
Current Water Vapor and upper air models show upper ridge over the
Great Lakes region, while upper low sits just off the PAC NW, with
southwest flow over the forecast area. Surface analysis shows cool
running through the forecast area this afternoon with breezy
northwest winds behind the front. Ahead of the front winds are breezy
out of the south to southwest. Temperatures currently sit in the
70s and low 80s.
Front will continue through the forecast area this evening, with
slightly cooler temperatures, however still well above normal for
this time of year. Some models hint at light shower potential over
the Black Hills with lee-side convergence late afternoon into the
evening, however very little available moisture today. Breezy
post frontal winds will diminish this evening as well.
Upper ridge builds into the northern and central plains Thursday
and Friday, prompting an increase in temperatures. Some record
daily highs could be possible on Friday, with NBM probabilities of
90 degrees or higher in the afternoon reaching into the 60-90
percent range for the southern half of the western SD plains. Deep
mixing will also allow for some breezy winds Friday afternoon,
with gusts 25 to 35 mph over some areas of the plains.
We`ll start to see a pattern shift Saturday, as upper trough digs
into the Rockies and into the northern plains by Sunday. A
shortwave and associated cold front is expected to move through
around this same time frame. Models show a 15-20 degree change,
with highs on Sunday only in the 50s to mid 60s. Better forcing
and moisture with this wave will bring a good chance for wetting
precipitation Saturday into Sunday. LREF probabilities for 0.5"
QPF or greater show a widespread signal of 50-80% chances later
Saturday into Sunday. This pattern looks to stick around at least
through early next week, with temperatures staying at or below
normal, with perhaps a few chances for precipitation.
&&
.AVIATION...(For the 18Z TAFS Through 18Z Thursday)
Issued At 1127 AM MDT Wed Oct 1 2025
VFR conditions will continue through the forecast period.
&&
.FIRE WEATHER...
Issued At 116 PM MDT Wed Oct 1 2025
Above normal temperatures are expected through Friday with
readings from 15-25F above average by Friday. Minimum relative
humidities should dip into the teens Thursday/Friday, particularly
over the southwest half of the CWA. Expect gusty winds at times,
which may support Fire Weather headlines (30% chance >25 gusts
Thursday, 40-80% chance >25 gusts Friday). However, the strongest
winds might not overlap the lowest relative humidities. Regardless,
at least elevated fire weather conditions sure to unfold. High to
very high grassland fire danger over the southwestern SD plains
expected. A cold front will bring relief for the weekend with
cooler temperatures and increasing chances for wetting
precipitation.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...None.
WY...None.
&&
$$
DISCUSSION/KEY MESSAGES...Dye
AVIATION...Smith
FIRE WEATHER...Dye

NWS UNR Office Area Forecast Discussion