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 remains the strongest tornado ever recorded in the state and the only recorded F4/EF4 tornado in Wyoming history. The tornado cut through a 39.2-kilometre (24.4 mi)-long and 2.5-kilometre (1.6 mi)-wide swath of the Teton Wilderness and Yellowstone National Park, crossing the Continental Divide. 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. At the time, it was the highest-elevation tornado known, since surpassed by several others, including a 2004 tornado above 12,000 feet in California's Sequoia National Park. While no human fatalities or injuries occurred, an estimated one million trees were felled by the tornado. The tornado damage was originally thought to be the result of strong thunderstorm straight-line winds until the area was surveyed by University of Chicago severe weather meteorologist Ted Fujita and his colleagues, who published a paper in 1989 surveying the tornado's path and discussing its meteorological character.