A rotating, organized thunderstorm with a persistent updraft is called a supercell.
Its defining feature is a rotating updraft known as a mesocyclone. Rotation helps the storm remain organized for much longer than an ordinary short-lived thunderstorm. Supercells can produce large hail, damaging straight-line winds, intense rainfall, and tornadoes, although not every supercell produces a tornado.
Strong vertical wind shear—wind changing speed or direction with height—is especially important in supercell formation. Shear separates the storm’s updraft and downdraft regions, allowing the updraft to persist instead of being quickly choked by its own rain-cooled air.
Meteorologists commonly classify supercells by their dominant precipitation structure, including classic, high-precipitation, and low-precipitation types. The term describes storm organization, not a guarantee of a particular hazard.