More bad weather could hit Iowa, where 3 powerful tornadoes caused millions in damage

For block after block through the small city of Greenfield, Iowa, the destructive power of an EF-4 tornado that ripped apart more than 100 of the town's homes in just one minute is evident in the muddy, shattered mess left behind.

All along the mile-long swath Thursday was the deafening clamor of heavy equipment scooping up the splintered homes, smashed vehicles and shredded trees. But on either side of that path, picturesque houses and lawns seem untouched, and one might be hard-pressed...