The Unusual Movement of the El Reno Tornado

There is a discussion on Facebook about the El Reno tornado: It turned right. No! Left. No Right.

The answer is both are correct and it is part of what made this tornado so incredibly dangerous I posted the items below Saturday and am reproducing here verbatim:

What happened [regarding the movement of the tornado]? In the simplified diagram below, the tornado (smaller black circle) was embedded 

within the larger mesocyclone (wider circle) that was moving east (black arrows). The tornado rotated around the mesocyclone (purple arrows) producing a sinusoidal pattern (example below).

This movement is clear when one time-lapses the velocity data. 

Smaller tornadoes don't behave that way and I suspect the chasers hadn't fully figured out the risks.

I assure you there is a lot of soul-searching in the chaser world today, as it should be.

Addition: Sunday morning... One meteorologist is critical of this posting because I tried to simplify the explanation by using the more familiar word "sinusoidal" (as in sine wave) than a word familiar primarily to meteorologists,"cycloidal." Below, from Wikipedia, is the more technically correct illustration.

There is an excellent animated illustration at Wikipedia.


ADDITION 2PM MONDAY: While not as good as an animation of the velocity data, you can see the cycloidal pattern in the hook echo in this animation.