699
FXUS63 KUNR 251742
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
1142 AM MDT Wed Jun 25 2025

.KEY MESSAGES...

- TSRA chances continue today, lower Thursday through Saturday,
  then pick back up again Sunday into early next week
- Sufficient buoyancy/shear for strong/severe storms through the
  period, but low confidence in details
- Warmest temperatures Friday/Saturday

&&

.DISCUSSION...(Today Through Tuesday)
Issued at 206 AM MDT Wed Jun 25 2025

07z surface analysis had low over southeast WY with several
boundaries extending from it into eastern MT and southern SD.
Water vapour loop had right entrance region of 130kt jet steak
over the CWA which was assisting a couple clusters of TSRA early
this morning in an environment characterized by 0.5-1KJ/kg
MUCAPE/25-35kt effective bulk shear. A couple of stronger storms
have been noted over the past few hours. Main concern this
forecast is convection chances.

Today/tonight, upper trough over UT/NV moves northeast as it
weakens and is absorbed into west/southwest flow aloft. Early
morning elevated TSRA should wane and then pick back up again
during peak solar insolation this afternoon. 0.5-1.5KJ/kg CAPE
will be available with sufficient shear for strong/isolated severe
thunderstorms. However, enough SBCIN should be around to suppress
organized convection especially with low clouds to start the day
for some areas. Temperatures will be near guidance.

Thursday, thermal ridge expands into the CWA with decreasing
CAPE/shear which should limit TSRA chances, except in/near the
Black Hills where terrain influences will occur. Friday will be
the warmest day of the week with temperatures well into the 90s on
the SD plains. A surface trough will move through during peak
heating, which may trigger strong/severe thunderstorms east of the
Black Hills. Warm day Saturday will become slightly cooler for
Sunday into early next week as northwest flow sets up per upper
ridge building over the Rockies. This ridge will eventually push
back into the plains.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Thursday)
Issued At 1142 AM MDT Wed Jun 25 2025

Isolated/scattered TSRA will develop this afternoon and evening.
Any TSRA will have local IFR conditions as well as gusty, erratic
winds and possible hail. MVFR/IFR CIGS conditions may develop late
tonight/Thursday morning across the northwestern to central SD
plains.

&&

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

$$

DISCUSSION/KEY MESSAGES...Helgeson
AVIATION...13