Weather Spotter’s Field Guide - Tornadoes 101 (2024)

Tornadoes, in and of themselves, are not bad as their formation is the way the Earth's atmosphere releases energy. Yet they are one of nature’s most fearsome creations due to the destruction they cause.

Each year they constitute a major hazard around the United States. You help to increase warning lead time by recognizing and reporting clues associated with tornado development and the various stages of the tornado life cycle.

Understandably, the vast majority of tornadoes occur east of the Rockies along with the number of thunderstorms. However, unlike where the greatest the number of thunderstorms occur, most tornadoes occur in the Central Plains.

While it is true the Central Plains experiences the annual greatest number of tornadoes on average, the area with the greatest risk of a tornado shifts each season. In winter, the Gulf Coast state from Louisiana to Georgia tend to have the most tornadoes on average.

In Spring, this area shifts into North Central Texas and Oklahoma. By summer, the risk area moves north to the Central and North Plains.

In Autumn, the season wih the least number of tornadoes on average, the main risk area has shifted back south, extending from East Texas into Mississippi. Finally, the risk area returns back to the Gulf Coast states in winter.

Tornado rating

The National Weather Service is the only federal agency with authority to provide 'official' tornado EF Scale ratings. The goal is to assign an EF Scale category based on the highest wind speed as indicated by damage.

NWS personnel conduct storm damage surveys to determine the strength of the storm. Based upon multiple criteria (a building's type, age, construction material, degree of damage, etc.) a maximum wind speed is assigned to the storm which then determines the EF rating.

Following is a broad definition of damage that occurs with each EF Scale rating.