Ada, South Dakota Weather Forecast Discussion

939
FXUS63 KUNR 220700
AFDUNR
Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
100 AM MDT Mon Sep 22 2025
.KEY MESSAGES...
-Cool front will bring breezy winds and a few showers/storms to
 the area today
-Dry with temperatures at or above normal the rest of the week
&&
.DISCUSSION...(Today Through Sunday)
Issued at 1257 AM MDT Mon Sep 22 2025
Northern Rockies trough will track south into the central Rockies
today and force a cold front through the area. After this trough
passes through the region, a blocking ridge will then build into
the western and central CONUS, supporting dry and warm weather
through the remainder of the week. Mostly clear skies and light
winds across the FA this morning. Moist easterly upslope flow may
allow for a few areas of fog this morning on the SD Plains. Upper
trough will dive SE into the central Rockies today, forcing a cold
front into the region. Main lobe of forcing will shift southwest
of the FA with the best rain chances. However, plenty of moisture
will be on the east side of this system, supporting decent
elevated CAPE over southwest SD. Progs suggest 1-2 KJ/KG of
elevated CAPE just east of the Black Hills on the SD Plains INVOF
of a trough axis aloft. This will allow for convection to develop
later this afternoon and evening, somewhere between Rapid City and
Phillip on a north south axis as many hires models suggest, with
convection zippering south along the trough. Given progged CAPE
values, cannot rule out a few stronger cells capable of larger
hail. However, any storms will likely be of a pulse nature given
lack of sufficient cloud bearing shear. Outside of this area of
focus, other high based showers will be possible, generally along
and south of I90. Shower activity will then shift south out of the
area overnight with the upper trough`s support. In addition to
rain chances, gusty northwest of 25 to 45 mph are expected on the
far western SD Plains today, breeziest east of the Black Hills,
with winds gradually tapering off through Tuesday. Upper ridge
will then build across the Northern Plains the rest of the week as
a quasi-omega block develops, with dry weather and at or above
normal temps across the region. Highs will generally be in the 70s
and 80s with mostly clear skies. Given an active northern stream,
there will be the potential for backdoor cool fronts to advect
into the area later in the week. However, nothing of significance
is progged attm.
&&
.AVIATION...(For the 06Z TAFS Through 06Z Monday Night)
Issued At 1131 PM MDT Sun Sep 21 2025
A cold front will push through the region early in the period.
Expect winds to remain south/southwesterly ahead of the front
before becoming northwesterly around or after daybreak. Northwest
winds will increase behind this front with gusts around 25-30+ kts
possible later today. Some fog will develop across the SD plains
this morning, but this should remain east of RAP. Isolated
showers or storms are also possible late today near RAP, but
confidence is too low to warrant a TAF mention.
&&
.UNR WATCHES/WARNINGS/ADVISORIES...
SD...None.
WY...None.
&&
$$
DISCUSSION/KEY MESSAGES...JC
AVIATION...Melo

NWS UNR Office Area Forecast Discussion