What Was the Largest Tornado in the United States?

The United States is a rather large country, and various natural disasters are common in certain areas. The West Coast is prone to earthquakes, a potentially catastrophic supervolcano is located in Wyoming, and a portion of the country is designated as “Tornado Alley” for its frequent tornadoes. The U.S. has been the site of many devastating tornadoes in the past, and today we’re going to discover and identify the largest tornado in the United States.

Yet, before we can look at the largest tornado in the U.S., we have to define them.

What is a Tornado?

A tornado is a violently rotating column of air that reaches from the cumulonimbus clouds of a thunderstorm to the ground in most cases. Tornadoes often appear as condensation funnels, and they become more apparent as they pick up debris.

For the most part, tornados don’t tend to get incredibly large. On average, they will measure about 250ft across and have winds of 110 mph or less. However, some tornadoes are much larger and more powerful than those. Tornados most commonly form in the spring and summer in the United States.

Tornadoes (also called twisters, whirlwinds, and more) are classified by their strength rather than their size or duration. The current classification is measured using the Enhanced Fujita Scale, ranging from EF0-EF5 with the wind speeds as such:

• EF0: 65-85 mph
• EF1: 86-110 mph
• EF2: 111-135 mph
• EF3: 136-165 mph
• EF4: 166-200 mph
• EF5: 200 mph+

The stronger the tornado, the rarer it is for them to form. Relatively few EF5s have been recorded since the Enhanced Fujita Scale was introduced.

How Many Tornadoes Hit the United States Each Year?

According to the National Oceanic and Atmospheric Administration, about 1,000- 1,200 tornadoes form in the United States each year. The strongest tornadoes ranking EF4 and EF5 occur more frequently in the U.S. than in any other country throughout the entire world.

The number of spotted tornadoes has been increasing since the government started tracking tornados in 1950. However, that might not be due to changing climate conditions but rather the improvement of technology to track tornadoes.

Also, people live in more locations throughout the United States now than ever before, so it’s only natural that greater numbers of tornadoes are tracked by weather services.

Out of the 1,200 or so tornadoes that hit the US, about 1 a year is an EF5. Since 1950, only about 62 tornadoes have been classified as an EF5. As you might imagine, there is a correlation between the biggest tornadoes and the strongest tornadoes. We can use this data to help narrow our search for the largest tornado to strike the U.S.

What Was the Largest Tornado in the United States?

The largest tornado in the United States was the 2013 El Reno tornado, a tornado that measured 2.6 miles wide at its greatest width. The El Reno tornado was impressive yet devastating for many reasons, including its vast size.

The El Reno tornado formed a few miles southwest of El Reno, Oklahoma, the city for which the tornado is named. According to mobile Doppler radar, the tornado reached wind speeds of about 296 mph, with even higher speeds detected in the vortex. That means this was firmly an EF5 tornado capable of doing extreme damage to any areas it struck. The winds in this tornado were some of the highest ever measured on earth.

The tornado’s size at touchdown was rather typical, but it soon swelled to over a mile in width. At one point as it tore a path across the area, the tornado grew to 2.6 miles in width over thirty seconds. Meanwhile, the tornado was rapidly intensifying in terms of wind speed.

Fortunately, the majority of the tornado’s path placed it in rural areas away from people. Yet, eight people died as a result of the tornado, and 151 people were injured across Canadian County, Oklahoma.

Three of the individuals killed by this tornado were storm chasers, making this storm the first time that scientists were killed in pursuit of a tornado. In the aftermath of the tornado, researchers discovered that the death toll could have been much higher.

When the tornado warning was announced, many people fled in their vehicles to avoid the tornado. Unfortunately, that put many of them on highways in the path of the twister. Fortunately, the atypical tornado changed course, perhaps saving the lives of hundreds.

What Made the Largest Tornado in the United States Unique?

The 2013 El Reno Tornado was unusual in many regards. Of course, the size and wind speed of the tornado was somewhat unusual. Even stronger tornados, like the 1999 Bridge Creek Tornado, did not have such a wide vortex.

That’s not all that made this tornado unique, though. At one point, the tornado was projected to travel into the Oklahoma City metro area, a highly populated place. During that time, local media issued warnings, including one unfortunate advisory that called for people to flee the area in their vehicles.

While this was happening, a major highway came to a standstill with traffic. Hundreds of cars and drivers were in the path of the storm. Fortunately, before the tornado bore down on Oklahoma City, it took a northeast turn and avoided the packed highways and highly populated areas. Shortly after, it dissipated after spending 40 minutes on the ground.

Although sudden changes in the tornado’s path probably saved travelers’ lives, they also cost veteran storm chasers their lives. Every tornado is unpredictable. Yet, the 2013 El Reno Tornado was especially unpredictable, changing directions and sizes so quickly that many experienced scientists were caught by surprise.

Another interesting fact about this tornado was that it was originally classified as an EF3 due to the lack of structural damage to support an EF5 rating. That was probably due to the tornado not hitting populated areas, though. The storm was upgraded to an EF5 at a later time based on radar measurements.

The 2013 El Reno Oklahoma tornado was the largest tornado in the United States. Although it claimed the lives of storm chasers and injured many people, this immense and powerful storm could have been far worse.  

The photo featured at the top of this post is © iStock.com/RomoloTavani