Sundance, Wyoming Weather Forecast Discussion

069
FXUS63 KUNR 160741
AFDUNR
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
141 AM MDT Tue Sep 16 2025
.KEY MESSAGES...
-Cool and unsettled most places through Thursday with scattered
 showers and thunderstorms
-Some locations may see an inch or more of rain where the most
 persistent showers occur
-Drying out and warming toward the end of the week
&&
.DISCUSSION...(Today Through Monday)
Issued at 140 AM MDT Tue Sep 16 2025
Semi-blocked pattern will develop as an upper low slowly migrates
east into the Northern Plains and phases with a southern Canadian
trough, all the while a sharp ridge develops over western NOAM.
This will set the stage for near widespread rain chances, with the
best chances for rain in portions of western SD. There will be
the potential for locally heavy rain given overall slow system
speed, slow individual cell movement, and PW`s around an inch,
with some locations expected to see over an inch of rain. Given
mesoscale nature of precip, the exact area that will see the most
rain cannot be pinpointed attm as forecast models continue
offering varying solutions on where the most persistent showers
will occur. Upper low will shift east today with impulse ladden SW
flow aloft. Expect scattered showers and TS developing today with
activity becoming sfc based this afternoon per diurnal heating.
Isolated stronger storms will be possible across scentral SD where
ML CAPE of 1-2 KJ/KG will be in place although deep layer bulk
shear is lacking. Shower chances will continue through Wednesday
most places as plenty of moisture will wrap into this system with
general LSA prevalent across the area. The best chances for rain
will occur where the system deformation zone sets up, the location
of which still remains uncertain. Dry air will begin to shift
into the region west to east Thursday with rain chances shifting
east as well. Much cooler through Thursday with clouds and rain in
place, esp where showers persist. Expect highs generally in the
60s and 70s most places. Things dry out this weekend with warmer
temperatures back into the 70s and 80s.
&&
.AVIATION...(For the 06Z TAFS Through 06Z Tuesday Night)
Issued At 1130 PM MDT Mon Sep 15 2025
Mostly VFR conditions are expected through the TAF period. Northwest
winds will become northerly towards or shortly after daybreak.
VCSH are anticipated near TAF sites towards the end of the TAF
period however not enough confidence on timing to throw into the
forecast just yet.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...None.
WY...None.
&&
$$
DISCUSSION/KEY MESSAGES...JC
AVIATION...Melo

NWS UNR Office Area Forecast Discussion