An average of 1,200 tornadoes hit yearly, and the United States will probably get more killer supercells spawning tornadoes and hail as the world warms.

The severe weather stretched from Texas to Ohio, causing tornadoes and flooding across the central United States.

A life-threatening outbreak of long-lived and strong tornadoes is expected today in parts of the central and eastern US from a powerful, wide-reaching spring storm.

A powerful F3 tornado touched down in Hanover, Pennsylvania, on April 5, 1952, leaving a 17-mile path of destruction. The tornado, the strongest ever recorded in York County history, caused $2.5 million in damages, equivalent to about $30 million today.

The National Weather Service described the disaster as "a once-in-a-generation to once-in-a-lifetime" event, warning that the worst may still be ahead.

More than 1,000 tornadoes sprout up across the United States in the average year, causing billions of dollars in damage and killing scores of Americans. The storms occur across the country throughout the year,