087
FXUS63 KUNR 241906
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
106 PM MDT Tue Jun 24 2025

.KEY MESSAGES...

- Marginal to slight risk (1-2 out of 5) of severe thunderstorms
this afternoon/evening
- Unsettled Wednesday with a marginal risk (1 out of 5) of severe
thunderstorms
- Warmer temperatures through Saturday, with at least a slight
chance for storms each day

&&

.DISCUSSION...(This Evening Through Tuesday)
Issued at 105 PM MDT Tue Jun 24 2025

Southwest flow continues over the northern plains, with a jet
streak over the Four Corners region. The surface high has shifted
into eastern ND, resulting in light easterly winds across our CWA.
Satellite depicts persistent low clouds across northeastern WY
and southwestern SD, keeping temperatures there cooler (in the
60s). This may inhibit some storm development, but as shortwave
energy pushes into the region, a couple of elevated storms have
developed above the low clouds.

Latest model forecasts of MLCAPE are slightly lower than
yesterday`s, but the shear forecast remains high. Forecast
ingredients for tornadoes seem to line up better across northeastern
WY, but surface-based storms may not be able to develop. A couple
CAMs still show potentially strong storms moving through
northeastern WY this afternoon, but a couple other CAMs are showing
only weak showers, possibly due to the aforementioned low clouds.
Nonetheless, much western SD remains fairly capped, so not expecting
widespread severe storms there.

Plentiful low-level moisture and easterly upslope winds may result
in some patchy fog over the Black Hills and eastern foothills early
Wednesday morning.

Better buoyancy and good shear are expected again on Wednesday.
Upper-level pattern would be messy, but models show a slightly
stronger signal of a shortwave moving across northwestern SD, which
may be a focus for some storms to develop.

Warmer and mostly dry weather can be expected Thursday, although
cannot rule out the chance for a stray thunderstorm, especially over
the Black Hills.

Strong southerly flow ahead of an approaching surface trough will
bring in warm, moist air across the SD plains. MLCAPE in excess of
2000 J/kg is forecast, along with around 30 kts of 0-6 km shear.
Storms may develop along the trough, with the potential for them to
become severe. Whether the storms develop within our CWA will depend
on the timing of the trough passage.

Yet another shortwave moves through Saturday, and ingredients look
sufficient for another round of strong to severe storms. Beyond
that, models are hinting at an upper ridge developing.

&&

.AVIATION...(For the 18Z TAFS Through 18Z Wednesday)
Issued At 1140 AM MDT Tue Jun 24 2025

MVFR CIGS are lingering over northeastern WY/southwestern SD late
this morning but improvement to VFR is still expected over the
next few hours. Thunderstorms will initiate this afternoon,
affecting NE WY and portions of western SD. There is still some
uncertainty as to the location and timing of storms, but MVFR/IFR
conditions are possible near any precip. Behind the storms later
tonight, easterly upslope flow will promote IFR/MVFR CIGS over
much of the area.

&&

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

$$

DISCUSSION/KEY MESSAGES...Pojorlie
AVIATION...13