Wyoming experiences tornadoes, though their frequency and intensity are lower compared to the traditional “Tornado Alley” states further east. The state ranks significantly lower than its plains neighbors in the annual count of these rotating columns of air. While the risk of a major, long-track tornado is diminished, Wyoming still records several events each year. The nature of these storms is heavily influenced by the state’s unique topography, resulting in specific patterns of occurrence and formation.
Frequency and Geographic Distribution
Wyoming experiences an average of 10 to 12 tornadoes annually. This places it near the middle of US states for frequency, but lower when considering the vast land area. Historical data shows a wide range of activity, including an unusually high count of 42 tornadoes recorded in 1979. Most tornadic activity is concentrated in the eastern third, where the Great Plains begin and the terrain is flatter.
The southeast corner holds the highest risk, particularly Laramie County (Cheyenne area), which accounts for over 16% of the state’s total recorded tornadoes. Neighboring counties such as Campbell and Goshen also show higher concentrations of activity. In sharp contrast, mountainous western regions, like Teton County, have recorded only a handful of tornadoes since 1950, highlighting the protective effect of the high-altitude terrain.
Seasonal Timing and Typical Strength
Tornadoes in Wyoming follow a seasonal pattern, peaking during the late spring and early summer months. June is the most active month, accounting for approximately 43% of all recorded events. The season generally runs from May through July, when daytime heating is maximized and atmospheric conditions support thunderstorm development.
These events typically occur during the late afternoon, peaking around 3 PM local time. This timing is directly related to the maximum solar heating of the day, which helps create atmospheric instability. The majority of tornadoes observed in the state are weak, classified as EF0 or EF1 on the Enhanced Fujita (EF) Scale.
Tornadoes rated EF2 or stronger are rare, occurring in less than 5% of Wyoming’s total recorded events. However, the state has experienced powerful exceptions, such as the F3 tornado that struck Cheyenne in 1979. Another significant event was the F4 tornado that occurred in the Teton Wilderness in 1987, causing extensive damage to timber at high elevations.
How Elevation Shapes Tornado Activity
The state’s high elevation and proximity to the Rocky Mountains significantly influence the mechanism and strength of its tornadoes. The mountains act as a barrier, disrupting the prevailing low-level air flows from the Gulf of Mexico that fuel the most powerful supercell thunderstorms further east. This topographical interference tends to destabilize the organized vertical wind shear required for long-lived, intense tornadoes.
Many vortices that form in Wyoming are “landspout” tornadoes, which differ fundamentally from those generated by supercells. A landspout does not originate from a rotating updraft within an organized storm. Instead, it forms when a pre-existing circulation near the ground, such as a dust devil, is stretched vertically by a growing thunderstorm’s updraft. These landspouts are typically narrow, short-lived, and rarely exceed EF0 or EF1 intensity.
The high altitude also affects air density, which plays a role in damage ratings. For instance, the 1987 F4 tornado in the Teton Wilderness occurred at elevations up to 10,000 feet. The thinner air meant that higher wind speeds were required to cause the same level of damage seen at lower elevations. While tornadoes are less common in the mountains, the occurrence of an F4 event at such high altitude dispels the idea that elevation entirely prevents their formation.