Happened to me (as I suspect to a fair number on here) some years ago, I wrote about it on here previously. Ironically also AA, on LAX-LHR, over The Rockies (experience of that route is this is a regular hit point). Completely unexpected by crew. Diverted to Chicago, one FA injured by being thrown up and down. Needed a crew change before heading on to London. Although striking and breaking the lightweight ceiling panels looks spectacular, the injuries occur as you come back down again. The bulk of the problems, on discussion with the crew, were in the rearmost cabin and galley.
Drinks were being served in Y, notable was a glass of red wine just ahead which went up and then down some seats away in a parabola. The contents took a slightly different trajectory, and slowly came out of the glass in a mass, like something out of a Mickey Mouse cartoon, and came down all across one poor guy a seat or two beyond where the plastic glass landed. He was still wearing hugely stained clothing on arrival at Heathrow.
I notice on flights from London to the Far East/Australia that UK/Australian carriers will reroute around weather systems; the Asian carriers less so.