Meteorologists rank tornadoes on the Fujita, or F-scale, with F0 being the weakest and F5 the strongest. In the recorded weather history of Delaware, New Jersey, and southeastern Pennsylvania, there's never been an F4 tornado, let alone an F5. Such extreme tornadoes are very rare in Maryland as well.

But a month ago, a powerful tornado - originally rated F5 but later reclassified as F4 - carved a seventy-mile-long path several hundred yards wide through three counties in southern Maryland, killing three people, injuring 90, demolishing stores and houses and littering streets with overturned cars and fallen power lines and trees. In this satellite animation, you can follow the evolution of the severe thunderstorm that spawned this tornado as the complex of storms moved out of Ohio through West Virginia and into Maryland.

The tornado dissipated before reaching Salisbury, Maryland, just south of the Delaware state line, making it the closest that an F4 tornado has ever come to the state of Delaware.