Brad Gryder writes:

Satellite photo of Southeastern USA on Friday 07Feb2020 with upper
level winds out of the southwest while surface winds are out of the northwest:

Over central South Carolina at 1:22 pm, the air just above the cumulus tops is
being rolled-up due to the ~90 degree shear, causing closely spaced horizontal
vortices and visible cloud streets:

At 1:29 pm, about 55 miles north of the above photo, there is a drier patch or
air, but the rolling continues:

At 1:32 pm, about 7 miles further north, the air is even drier:

At 1:42 pm, about 70 miles further north, the air is moist again near the NC/SC
border:

The most violent turbulence was encountered in the clear air above the clouds,
perhaps within 1000’ above the tops. The turbulence within the clouds and below
them was minor compared to the air just above the clouds. At this latitude in
early February, the solar energy at the surface adds limited contribution to the
lift, with most of the lift coming from the dynamic energy of the shear layer.
This is especially true when the ground is saturated with recent rains less than
24 hours ago.