328
FXUS63 KUNR 031124
AFDUNR

Area Forecast Discussion For Western SD and Northeastern WY
National Weather Service Rapid City SD
524 AM MDT Wed Jun 3 2026

.KEY MESSAGES...

- Severe storms possible across south-central South Dakota on
  Wednesday.

- Chance of severe weather with all hazards possible Thursday.

&&

.UPDATE...
Issued at 1024 PM MDT Tue Jun 2 2026

Main focus this update is near-term pops and thunderstorm
potential over the next couple days. Models have not handled
location and overall progression of storm trends this evening. Low
level jet strengthening tonight will allow storms to linger into
the overnight hours, albeit losing a bit of their strength. Still
could see some marginally severe pulse storms overnight. By
morning storms should be more in central SD. As another
disturbance pushes through the Dakotas Wednesday, some storms are
expected to form along the boundary in the late afternoon early
evening timeframe. Main concern will be over south central SD as
the storms form. CAPE values in the 2000-3000 j/Kg and 30-40kt
0-6km shear will support some severe potential over south central
SD. A better chance for more widespread storms with severe
potential returns Thursday.

&&

.DISCUSSION...(This Afternoon Through Monday)
Issued at 1109 AM MDT Tue Jun 2 2026

Upper level analysis has the forecast area in southwest flow with a
low over southwestern Saskatchewan and a skinny ridge extending up
through the Mississippi River Valley from High Pressure in the
Southern Plains. At the surface, a cold front extends through
eastern Montana into southeastern Wyoming. Radar imagery has
thunderstorms already firing in the warm sector east of the
boundary.

For this afternoon and evening, the cold front will provide the
primary focus for thunderstorm development. As this front moves
slowly east, development will likely occur over the Black Hills and
most of western South Dakota, especially across northwestern South
Dakota. Model soundings show steep lapse rates, deep layer sheer and
MLCAPE around 2500 J/kg. These ingredients suggest the potential for
supercell storms capable of producing large hail, severe winds, and
even a tornadic storm. Additionally, the presence of a low level jet
this evening should result in storms continuing through late evening
and possibility into the early morning hours.

The cold front will move slowly east on Wednesday as the upper low
slowly shifts into southeastern Saskatchewan and western Manitoba.
Models indicate a secondary surface low will spin up over central
South Dakota with a trailing cold front into western Nebraska
panhandle. This boundary will once again be the focus for convective
initiation during the afternoon and evening hours. Again, these
storms will have the potential for large hail and strong wind gusts.
Forecast soundings indicate steep lapse rates, MLCAPE around 2500
J/kg over central South Dakota, and shear up to 35-40kts over south
central South Dakota, though shear is forecast to be much higher
across north central South Dakota.

Thursday will be another big day for severe storms across the
forecast area as the upper low slides through Manitoba and a
shortwave crosses the Rockies into the forecast area by Friday
afternoon and evening. At the surface, a low will spin up over
southeastern Montana and slide into west-central Nebraska. This
boundary will be the focus for severe storms on Thursday with
diurnally enhanced development. The environment looks like a typical
northern Black Hills supercell environment capable of very large
hail. Additionally, storms may end up growing into an easterly
propagating MCS overnight, resulting in a severe wind threat for
south-central South Dakota by late evening.

On Friday, could have some lingering showers in the morning, as the
cold front drops southward and a wave clips northwestern South
Dakota. Also, some diurnally driven showers are possible over the
Black Hills in the afternoon.

Saturday appears to be mainly dry as a weak shortwave ridge slides
through the area, with chances for storms returning Sunday through
early next week.

Temperatures through the period will gradually warm through this
weekend, with highs running about 10 degrees above average and lows
about 5 degrees above average.

&&

.AVIATION...(For the 12Z TAFS Through 12Z Thursday Morning)
Issued At 522 AM MDT Wed Jun 3 2026

MVFR/IFR CIGs are ongoing over parts of northeastern Wyoming, the
Black Hills, and northwestern SD this morning and will improve to
VFR late morning. VFR conditions are then expected for both TAF
sites the remainder of the day. More strong to severe storm
development will be possible across south central SD late this
afternoon.

&&

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

$$

UPDATE...Dye
DISCUSSION/KEY MESSAGES...Schultz
AVIATION...Dye