From the Field

Tornado facts: How they form and how to prepare

A flooded neighborhood rescue scene where water is up to people’s knees due to a storm.

Tornadoes, with their powerful winds and potential for devastation, can strike anywhere. To safeguard the well-being of yourself and your family, it’s vital to stay informed and prepared. Discover important tornado facts and steps for tornado safety and preparedness to ensure the security of your loved ones during times of crisis.

Tornadoes: Facts, FAQs, and how to help

Fast facts: Tornadoes

  • A tornado is a rapidly rotating column of air that extends from the base of a thunderstorm to the ground.
  • Tornadoes form when warm, moist air collides with cold, dry air, creating unstable atmospheric conditions.
  • A twister can have wind speeds ranging from less than 100 mph (weak tornadoes) to over 200 mph (violent tornadoes).
  • Tornadoes can vary in size from just a few yards across to more than a mile wide. They can last for a few minutes to nearly an hour, although some may persist longer.
  • The central United States, known as Tornado Alley, is prone to frequent tornadoes due to its geography and climate. It spans from northern Texas to South Dakota, where supercell thunderstorms often produce destructive twisters.
  • Tornadoes can occur at any time of year, but they’re most common in the spring and early summer, especially in the northern Plains and upper Midwest. Most twisters happen between 4 and 9 p.m.
  • Tornado watches vs. warnings: A tornado watch means conditions are favorable for tornadoes, while a warning indicates a tornado has been detected and immediate action is needed.


What makes tornadoes so destructive?

Tornadoes, also referred to as twisters, unleash intense high winds that can topple trees, flatten buildings, and destroy roads. A significant contributor to their destructiveness is the debris they transform into projectiles. Traveling through a populated area, the funnel of a tornado picks up and carries millions of small and large items, including trees, rocks, trucks, parts of houses, and broken glass. These projectiles can cause damage proportionate to their size and speed when they collide with buildings or homes or crash to the ground.


What is the rating scale for tornadoes?

Tornadoes are now rated on the Enhanced Fujita (EF) scale, ranging from EF0 (65–85 mph) to EF5 (over 200 mph). It is nearly impossible to accurately measure the speed of a tornado, as any measurement device would be destroyed. The EF scale assesses the intensity based on estimated 3-second wind gusts, calculated using 28 different damage indicators — from softwood trees to schools. For example, if a tornado obliterates a large shopping mall or a large section of one, the wind speed would be estimated at 204 miles per hour, characterizing it as an EF5.


What is an EF5 tornado?

An EF5 is the most powerful tornado, causing incredible damage with winds over 200 mph. Capable of destroying schools and large shopping complexes, and causing permanent structural deformation to even 20-story buildings, EF5 tornadoes are rare. They account for only 1% of all tornadoes but are responsible for 37% of tornado-related fatalities. The National Weather Service maintains a list of all the EF5 tornadoes since 1950.


What are some recent EF5 tornadoes?

A formidable EF5 tornado struck Moore, Oklahoma, on May 20, 2013, with recorded peak winds of 210 mph. The disaster resulted in the tragic loss of 24 lives, the destruction of over 1,100 homes, and an estimated $2 billion in damages. The disaster stands as one of the costliest tornadoes on record. Just 11 days after that disaster, another EF5 and the largest tornado ever recorded, measuring 2.6 miles across at its peak, hit near El Reno, Oklahoma, on May 31, 2013.


How do I prepare for a tornado?

The Federal Emergency Management Agency provides guidelines to help you and your family stay safe during and after a tornado. When a tornado warning is issued, taking immediate action is critical. For example:

  • Go to a safe room, basement, or storm cellar.
  • If no basement exists, reach a small interior space or room on the lowest level.
  • Stay away from windows, doors, and outside walls.
  • If you can safely get to a sturdy building, do so immediately.
  • Do not seek shelter under an overpass or bridge; you’re safer in a low, flat location.
  • Be vigilant for flying debris that can cause injury or death.
  • Use your arms to protect your head and neck.


How can I help people affected by disasters in the U.S.?

  • Pray: Join us in praying for children and families impacted by tornadoes and disasters.
  • Give: Your gift will help provide relief to survivors of U.S. disasters.


Chris Huber and Sevil Omer of World Vision’s U.S. staff contributed to this article.

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