811
FXUS63 KUNR 141740
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1140 AM MDT Tue Oct 14 2025

.KEY MESSAGES...

- Unsettled weather this week with gusty winds at times
- Isolated severe thunderstorms Wednesday night
- Best chance of rain later Wednesday into Thursday

&&

.DISCUSSION...(Today Through Monday)
Issued at 200 AM MDT Tue Oct 14 2025

07z surface analysis had high pressure from southern MB into the
Ohio Valley. Moderate pressure gradient on the back side with
gusty southeast winds at times. Water vapour loop had upper low
just off the CA coast with speedy southwest flow over the northern
Plains. Embedded shortwave spawning showers from northwest into
southeast SD per regional radar loop early this morning. Looking
upstream, several wiggles noted ahead of upper low. Disposition of
upper low the main forecast concern.

Through Thursday, upper low will move east today and then eject
northeastward into the northern Plains by Thursday. A series of
weak shortwaves ahead of it will bring a few showers to fruition.
Sustained southeasterly upslope flow will eventually lead to a
stratus fest, especially from the Black Hills eastward. Upslope
fog not out of the question tonight given forecast boundary layer
moisture profiles. Surface low will develop over eastern CO
Wednesday per approach of upper low. This will focus narrow band
of weak buoyancy over the CWA Wednesday night. Plenty of shear, so
isolated severe thunderstorms could occur, especially if they
emanate from better looking thermodynamic environment southwest of
the CWA. Latest guidance is hinting at a signficant dry slot over
the CWA by Thursday, which may cutoff PoPs earlier than current
forecast portrays. NBM probability of >0.25" QPF over the next 3
days is 50-80%, highest over northwestern SD. Temperatures will be
near guidance in the west where better solar insolation may
develop during the day, but potentially lower over western SD
where upslope flow/clouds will temper potential temperatures.

Friday into the weekend, northwest flow aloft becomes an upper ridge
leading to warmer weather for most folks. A colder upper trough may
move in for the first half of next week.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Wednesday)
Issued At 1135 AM MDT Tue Oct 14 2025

Areas of MVFR/IFR ceilings over central SD will shift westward
this afternoon and evening, invading the Black Hills area and
KRAP terminal by 03z. Areas of IFR/LIFR fog and drizzle should
also develop after 03z across the SD plains. Scattered rain
showers are likely further west across WY overnight.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...None.
WY...None.
&&

$$

DISCUSSION/KEY MESSAGES...Helgeson
AVIATION...15