EF0 is the weakest point on the Enhanced Fujita scale and EF5 is the strongest.

CNN: Tornadoes Fast Facts

The Fujita scale is used to estimate the wind speed of a tornado by the damage the tornado causes.

CNN: Tornadoes Fast Facts

Both years saw major storms (F4 or F5 on the F0-F5 Enhanced Fujita scale) plow very long paths through densely populated territory.

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The tornado was estimated to be an EF-5, the most devastating on the Enhanced Fujita Scale, with wind speeds exceeding 200 mph.

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The National Weather Service issued an initial finding that the tornado was an EF-4 on the enhanced Fujita scale, the second most powerful type of twister.

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The Tuscaloosa tornado was later given a rating of EF4, the second-most powerful on the Enhanced Fujita Scale, meaning it had wind speeds between 166 and 200 mph.

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Tornados are rated on several scales for strength based either on wind speed, pressure drop, or damaged caused, but the updated Enhanced Fujita Scale is the presently accepted scale in the United States.

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The strongest tornado, rated a maximum EF5 on the Fujita Tornado Scale, tracked for nearly an hour and a half along a 38-mile path from Chickasha through south Oklahoma City and the suburbs of Bridge Creek, Newcastle, Moore, Midwest City and Del City.

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