Teton–Yellowstone tornado

The 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 24-mile (39 km) long, 1.5-mile (2.4 km) wide swath of the Teton Wilderness and Yellowstone National Park, and even crossed the Continental Divide. The damage occurred at elevations ranging from 8,500 to 10,000 feet (2,600 to 3,000 m), 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.