A supercell thunderstorm, which brought almost hurricane-force straight-line winds, was responsible for a 300-mile swath of damage across northern Maryland and southern Pennsylvania on Saturday ...

Supercells are the mightiest of the thunderstorms. They can roll for hours while maintaining tornadoes and damaging hail. Here's what you should know.

Pottawattamie, Cass CountiesOne supercell storm produced multiple tornadoes north of Omaha before crossing into Pottawattamie County, Iowa. A spotter reported a possible tornado southeast of ...