What is the highest-elevation tornado? Do they happen in the mountain West?
The highest elevation a tornado has ever occurred is unknown; but it is at least 10,000 feet above sea level. On 7 July 2004, a hiker observed and photogaphed a tornado at 12,000 feet in Sequoia National Park, California. That probably was the highest elevation tornado observed in the U.S. On 21 July 1987, there was a violent (F4 damage) tornado in Wyoming between 8,500 and 10,000 feet in elevation, the highest altitude ever recorded for a ciolent tornado. There was F3 damage from a tornado at up to 10,800 ft elevation in the Unita Mountains of Utah on 11 August 1993. While not so lofty in elevation, the Salt Lake City tornado of 11 August 1999 produced F2 damage. On August 31, 2000, a supercell spawned a photogenic tornado in Nevada. Tornadoes are generally a lot less frequent west of the Rockies per unit area with a couple of exceptions. One exception is the Los Angeles Basin, where weak-tornado frequency over tens of square miles is on par with that in the Great Plains. Elsewhere, there are probably more high-elevation Western tornadoes occurring than we have known about, just because many areas are so sparsely populated, and they lack the density of spotters and storm chasers as in the Plains.