750
FXUS63 KUNR 161123
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
523 AM MDT Wed Jul 16 2025

.KEY MESSAGES...

- Showers/isolated thunderstorms continue today with 15-30F below
  normal temperatures
- Zonal flow promotes a return to summer by Sunday with daily
  opportunities for thunderstorms into next week

&&

.DISCUSSION...(Today Through Tuesday)
Issued at 227 AM MDT Wed Jul 16 2025

08z surface analysis had cold front south/east of the CWA with
high pressure over south-central Canada promoting northeasterly
upslope flow over western SD. Water vapour loop had upper trough
from SK to ID with lead wave over eastern WY assisting initial
band of shra/TS moving through the CWA. Main synoptic/QG-forcing
over MT/northwest WY sliding eastward with additional shra/TS
ahead of it. Disposition of upper trough the main short term
forecast concern.

Today, upper trough moves across the northern plains as initial
shra/TS shifts east of CWA and next band of precipitation slides
across the area. Latest HREF (50-80% chance >0.25" additional QPF)
guidance shows best QPF from second wave over the northern half
of the CWA. Upslope flow will support low clouds/fog at times and
perhaps even some drizzle outside of shra/TS. Temperatures will be
15-30F below normal with guidance depicting well.

Tonight, precipitation wanes this evening with perhaps some fog
overnight, especially in/near the Black Hills. As surface high
slips into the area, temperatures will be within reach of a few
record lows if low clouds/fog dissipate.

Thursday through early next week, zonal flow expected with a
series of disturbances moving across the US/Canadian border
dropping boundaries through the northern plains. An almost daily
chance of TSRA is painted, but plenty of dry hours are foreseen.
Thermal ridge expands into the area for the weekend with a return
to summery temperatures Sunday through Tuesday.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Thursday Morning)
Issued At 520 AM MDT Wed Jul 16 2025

Widespread MVFR/IFR/local LIFR conditions are expected through
this afternoon due to low CIGS, shra, fog and isolated TS.
Conditions may improve tonight from KD07-KICR, but other than a
reduction in precipitation, little change is expected for
northeastern WY/western SD tonight.

&&

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

$$

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