May.25, 1999 - cloud lowering

[DarkSky]

May 25, 1999 - 3pm I was watching the dark clouds roll by and noticed an area that began to lower. I couldn't quite tell what it was as it only lasted about 5 minutes. Here are some vidcaps showing it lower, expand into what almost looks like a non-rotating wall cloud, then retract and dissipate:
Visible bands in the tower as it rises straight up.
Cloud lowering appears.
Zoomed in on lowering.
Formation continues to lower...
Formation spreads out at bottom.
A few seconds later.
Grows thicker.
Retracts back up...