Photograph by Priit Vesilind
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An impending tornado darkens skies over the Colorado plains. Most tornadoes are 400 to 500 feet (122 to 152 meters) wide, travel four or five miles (six to eight kilometers), and last just a few minutes.

Photograph by Priit Vesilind

How to stay safe from tornadoes

Twisters can be deadly, but there are steps you can take to reduce risk to you and your family.

Tornadoes are one of nature's most powerful and destructive forces. Here's some advice on what a tornado is, how to prepare for one, and what to do if you're caught in a twister's path.

How does a tornado form?

A tornado is a violently rotating column of air that extends from a thunderstorm to the ground. It's often portended by a dark, greenish sky. Black storm clouds gather. Baseball-size hail might fall. A funnel suddenly appears, descending from a cloud. The funnel hits the ground and roars forward with a sound like that of a freight train approaching. The tornado tears up everything in its path. (Learn more about the science of tornadoes, including how they form.)

Some of Earth's most violent events, nearly a thousand tornadoes—many of them deadly—touch down every year in the United States. Every U.S. state has experienced twisters, but Texas holds the record: an annual average of 120. Tornadoes have been reported in Great Britain, India, Argentina, and other countries, but most tornadoes occur in the United States—a product of the regional geography and weather patterns.

How to stay safe

Tornadoes can be deadly, but there are steps you can take to reduce the risk to you and your family. Remember that although tornadoes are most prevalent in certain areas, they can appear suddenly in many places. Here are some things to keep in mind:

Prepare for tornadoes by gathering—ahead of time—emergency supplies, including food, water, medications, batteries, flashlights, important documents, road maps, and a full tank of gasoline.

• When a tornado approaches, anyone in its path should take shelter indoors—preferably in a basement or an interior first-floor room or hallway.

Tornadoes 101 Tornadoes, nearly three-quarters of which occur within the U.S., are unpredictable and can cause massive damage. New tools and data are helping scientists learn more about when they might form and what paths they might take.

• Avoid windows and seek additional protection by getting underneath large, solid pieces of furniture.

• Avoid automobiles and mobile homes, which provide almost no protection from tornadoes.

• Those caught outside should lie flat in a depression or on other low ground and wait for the storm to pass.