A week after deadly tornadoes tore through Western and Central Massachusetts, tree and debris removal continue (2011). © Flickr/Corps New England

Tornadoes are short-lived, relatively small, complex, violent and unpredictable storms that can cause severe damage though usually in limited areas. They are most common in spring in late afternoon and are concentrated in interior continental regions, particularly in Tornado Alley of the Great Plains of North America, but they can and do occur anywhere, especially in temperate latitudes. Tornado winds greatly surpass tropical cyclone winds in intensity, reaching an estimated maximum exceeding 400 km/h.

They develop under three meteorological conditions: long-lived supercell thunderstorms, which generate the largest and most damaging tornadoes; ordinary thunderstorms; and in cyclones after they make landfall. Damage to trees and forests can range from branch break and single tree gaps to extensive areas of complete blowdown.

last updated:  Friday, June 28, 2013