21-07-2025
On This Date: A Violent Tornado In Wyoming's Mountains
If I mention the phrase "violent tornado," what state first comes to mind — Oklahoma, Alabama or maybe Texas?
On July 21, 1987, 38 years ago this afternoon, a tornado touched down in northwestern Wyoming just east of Grand Teton National Park. Tornadoes can happen in mountainous terrain, but this was an exceptional twister by high country standards.
It tore a 24-mile path in 26 minutes from east of the town of Moran across the Continental Divide at just over 10,000 feet elevation before it lifted in the southeast edge of Yellowstone National Park. Nobody was killed, but nine campers witnessed a "fast-approaching train-like noise" along with large hail, according to WyoFile.
According to the U.S. Forest Service, 1 million trees were uprooted in a 15,000-acre swath, some of which you see in the photo below.
That grabbed the attention of the father of tornado science, Theodore Fujita.
Fujita coordinated three aerial surveys in the weeks after the tornado. In a study released just over 18 months later, he rated the tornado F4 with peak winds estimated at over 207 mph using the pre-2007 Fujita scale. Fujita assigned this rating based on observations of "uprooted large trees, spattered by wind-blown topsoil and debarked."
This remains America's strongest high-elevation tornado on record.
Fujita found the damage path was up to 1.6 miles wide, consisting of "swirl marks" indicative of the tornado, as well as 72 separate microburst outflows within the damage swath. Damage from the tornado was estimated at $2.5 million.
According to WyoFile, many of the downed trees were consumed the following summer by the Yellowstone wildfires of 1988.
Jonathan Erdman is a senior meteorologist at and has been covering national and international weather since 1996. Extreme and bizarre weather are his favorite topics. Reach out to him on Bluesky, X (formerly Twitter) and Facebook.
