Highest Elevation Tornado Ever Observed in U.S.

Tornado, Rockwell Pass, Sequoia National Park, California, July 7, 2004.

Elevation at Rockwell Pass: ~11,600 feet. Base of tornado at ground level probably at least at 12,000 feet.

Scott Newton, 2004

We had hail and lightning on the John Muir trail in 2007 at very high elevations. But certainly nothing like a tornado.

Scary stuff.

Thanks Rocco for forwarding the link.