Teton – Yellowstone tornado was a rare high-altitude tornado which occurred on July 21 , 1987 in the U.S. State of Wyoming . Rated at F4 on the Fujita scale , it was the strongest tornado ever recorded in the state . It was also the only recorded F4 tornado in Wyoming history . The tornado cut through a long , wide swath of the Teton Wilderness and Yellowstone National Park , and even crossed the Continental Divide . The damage occurred at elevations ranging from , making it the highest altitude violent tornado recorded in the United States . No human fatalities or injuries were recorded , but up to 1,000,000 trees were uprooted by the storm . The F4 rating was based on the severity of the tree damage in the worst affected areas . Huge swaths of trees were flattened , and many were stripped of leaves and limbs , with the trunks debarked . Topsoil was picked up and spattered against the bare trunks . Fujita noted that the tree damage was only comparable to that he had seen associated with some of the tornadoes from the 1974 Super Outbreak , as well as the April 1977 Birmingham tornado . Most of the damaged forest later burned in the Yellowstone fires of 1988
Yellowstone fires of 1988
Yellowstone fires of 1988
Teton–Yellowstone tornado