Imlay, South Dakota Weather Forecast Discussion

061
FXUS63 KUNR 101113
AFDUNR
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
513 AM MDT Wed Sep 10 2025
.KEY MESSAGES...
- Warm temperatures through Friday.
- Precipitation chances increase late Friday into Saturday with
  temperatures cooling to near normal readings.
&&
.DISCUSSION...(Today Through Tuesday)
Issued at 308 AM MDT Wed Sep 10 2025
09Z upper level analysis has ridge over the Northern Plains, with
weak trof lifting through central Montana. Large upper trof
remains over the West Coast. Skies are partly cloudy across the
Northern Plains with some weak isolated showers over the forecast
area. At the surface, weak boundary remains draped across the
forecast area, with no apparent temp or wind discontinuities.
Temperatures across the forecast area at 3 AM are in the 50s and
60s, with light east to southeast winds.
Upper ridge remains over the Northern Plains today, with southwest
upper flow impinging on western portions of the area. Weak surface
low begins to deepen over central Wyoming, and with surface high
pressure just to the east, a decent pressure gradient develops
over the forecast area this afternoon. Southeast winds will be
breezy, but remain under Advisory criteria. Mainly dry and warm
weather will continue, with isolated showers and thunderstorms
developing over western areas late this afternoon and into the
evening hours. A few stronger storms could produce some small hail
and strong gusty winds early this evening.
Wash, rinse, repeat for Thursday as upper ridge shifts a little
further east, and western trof moves into the Great Basin area.
Surface low over Wyoming will further deepen and lift into
Montana by mid morning. Breezy southeast winds will continue over
the area, along with above average temperatures. Increasing
shortwave energy in southwest flow aloft will bring a little
better chance of afternoon and evening thunderstorms to the area.
With increasing low level moisture from the persistent southeast
boundary layer flow, along with better upper level support,
there is a marginal (1 out of 5) risk of severe storms over much
of the area, with hail and strong gusty winds the main concern
through Thursday evening.
Progression of the upper trof/ upper low continues to slow down a
little with each new model run. Friday during the day is now a
little drier and warmer, with widespread showers and isolated
storms holding off until late in the day and into the overnight
hours. Ample moisture in southwest flow will bring a good amount
of rain to much of the area through Saturday, especially northern
and western portions of the forecast area. Precipitation totals of
a quarter inch or better are possible from northeast Wyoming
through west central SD. Amounts up to an inch will be possible
from the Black Hills area into northwest SD by Saturday night.
Unsettled weather lingers into Sunday, with a brief dry out for
Monday and Tuesday. But unsettled weather looks to continue past
that point as another upper trof crosses the Northern Plains from
the middle to latter parts of next week.
&&
.AVIATION...(For the 12Z TAFS Through 12Z Thursday Morning)
Issued At 509 AM MDT Wed Sep 10 2025
Mainly VFR conditions are expected across the area through the
TAF period. Breezy southeast winds will develop this morning,
resulting in gusts up to 25 kts at most locations. Isolated
thunderstorm chances will begin to increase around 20Z across
northeast Wyoming, and shift into western SD during the evening.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...None.
WY...None.
&&
$$
DISCUSSION/KEY MESSAGES...15
AVIATION...15

NWS UNR Office Area Forecast Discussion