First of all… the Badlands are awesome!!! I definitely want to make it back to the Badlands eventually. It is really unique and really really cool. We would have spent time hiking through the park had it not been for a tornado threat!!!!
It’s sort of an odd feeling severe weather day compared to what I’m used to. Dew points are in the low 60s (which is fairly high for the Black Hills) and a gusty easterly upslope flow has brought in a solid deck of stratocumulus trapped under the elevated mixed layer. Check out the special 20z weather balloon launch in Rapid City and you can see the shallow batch of moisture under the inversion.
The easterly boundary layer flow underneath strong southwesterly winds aloft results in a really strongly sheared atmosphere. SPC mesoanalysis pegs mixed layer CAPE values near 3000 j/kg to our southwest.
Continued moisture advection and QG forcing (lift) from an upper level disturbance swinging east from the Rockies will break the cap and we’ll get some nice storms to form. While the storms will initially be discrete (and possibly tornadic given the shear) they should quickly morph into a cluster and may even become a derecho across southern South Dakota and northern Nebraska.
For now we’re going to wait a bit in Rapid City and figure out where to chase from there. We may wind up heading south on Rt 79 a bit and attack these things from the south. Should be a very busy afternoon after a trip full of blue sky!