I am going with Dementor. Possibly Alien - probably a Kite. But you'd have to be standing in the middle of the busy street or Forest Lawn - both odd choices for kite flying in cloudy, stormy weather.
It hovered and floated and moved all over the place for a few minutes LOL It startled me silly. I am sticking with Dementor, although WeeCubeMan says it is a baby Demonoid and drew me a picture of one up close....
Probably best to have Expecto Patronum at the ready... you know, just in case.
Not vicious or malicious
Just de-lovely and delicious