On July 21, 1987, an F4 tornado tracked 24 miles across the Teton Wilderness into Yellowstone National Park. Over 1,000,000 trees were knocked down as the tornado slashed its way across mountain tops up to 10,000 feet high, and through valleys. This is the highest altitude in the US that a violent tornado (F4/F5) has ever occurred.
It is considered the most destructive tornado in Wyoming’s history. An F3 crossed through the northern parts of the Cheyenne housing and airport areas. Thomas Grazulis in Significant Tornadoes states this could have been a “minimal F4” tornado. And the NWS in Cheyenne originally believed that was an appropriate rating. Explore the history!