Twisters Past and Present: Interactive Tornado Tracker

By Climate Central

Tornadoes can happen anytime, anywhere in the world where conditions are right.

It just so happens that the U.S. is effectively the tornado capital of the world, with an average 1,200 tornadoes forming within its borders each year, according to the National Severe Storms Laboratory. Tornadoes have been observed on New Year’s Day, New Year’s Eve and every day in between, from California to Maryland, North Dakota to Texas.

With Climate Central’s Tornado Tracker, you can track tornado reports so far in the current year and investigate reports during past years. The tracker plots tornado reports from NOAA's Storm Prediction Center in Norman, Okla., and is updated multiple times a day to capture breaking events. (Keep in mind that tornadoes on the Tracker are just “reported” events, and have not yet been confirmed and that multiple reports can be sent in for the same tornado.)

Tornadoes happen when clashing air masses create an unstable environment, with some moisture thrown in there for good measure (though this doesn’t always result in a tornado—scientists don’t fully understand why). Generally, the prime time and location for this set of ingredients to come together is during spring and early summer, smack dab in the middle of the country—the proverbial Tornado Alley (though this is not a scientifically defined term). This is especially true for so-called supercell tornadoes, generally the strongest and most destructive, which are spawned by rotating thunderstorms.

May is generally the busiest month for tornadoes, but the most active month on record was April 2011, which saw 758 confirmed tornadoes (including April 27-28 outbreak in the Southeast that killed more than 300).

The peak of tornado season, or the time with the highest probability of at least one tornado occurring somewhere in the country is early June, but regionally the peak can vary. In Tornado Alley, for example, it can come anytime between late May and early July depending on the location.

Tornadoes are measured on the Enhanced Fujita scale, which runs from EF0 (weakest) to EF5 (strongest). The rating a tornado receives on that scale is determined by the amount and type of damage it does, which is evaluated by trained teams from the National Weather Service.

Those teams also determine how long the tornado was on the ground for—the average time is 5 minutes, according to the NSSL, but can be anywhere from seconds to hours—and how wide it was.

The bottom line is to be aware of any weather situations near you that could produce tornadoes, as well as any tornado watches or warnings that have been issue. (The first means that conditions are conducive to tornado formation, the second that one has been spotted on the ground or on radar.) And if there’s a tornado near you, get away from windows by heading to the basement or an interior room on the lowest floor and using a mattress or sturdy table to help shield you.