Several tornadoes raged Saturday afternoon and evening in Iowa. Winterset, Madison County, and Newton, Jasper County, were particularly hard hit, with homes and cars damaged or destroyed. Thousands of people were temporary without power. At least six people have died.

By Sunday, the local National Weather Service offices continue to survey damage across the state. There were at least 30 reports of tornadoes extending from southwest to central Iowa. Several homes and structures were hit, and even reports of homes leveled across south-central Iowa.

"This is the worst tornado damage I've seen in Madison County," the local disaster relief chief said. The extent of the damage points to an F3 tornado on the enhanced Fujita scale. This corresponds to wind speeds between 136 and 165 mph. In Orient, a city in southwest Iowa, huge hailstones smashed through the windshields of numerous cars.

A rare twin tornado even developed near the cities of Derby and Chariton, also in Iowa. A twin tornado occurs when two tornadoes form in close proximity.

Both tornadoes form in the same thunderstorm, usually in a so-called supercell. A supercell is a type of thunderstorm that poses a high risk of severe weather.

Supercells are the most dangerous thunderstorms. Cloudbursts, large hailstones, and extreme gusts of wind are intense side effects. A rotating vortex inside the cloud is characteristic of supercells. Ten to 20 percent of all supercells produce a tornado.

Tornados are small, rapidly rotating columns of air with a vertical axis. Thunderstorms usually produce tornadoes, and the cloud trunks can extend from the ground to the underside of the cloud. They can wreak havoc almost anywhere on Earth, with the majority of them raging in the American Midwest.