A tornado, waterspout, or a thunderstorm with winds of 50 knots (25 m/s) or greater and/or hail 3/4" (20 mm) or greater in diameter at the ground. Usually results to significant wind damage (several downed trees) and/or large hail. (GLIDE)
ReliefWeb - A specialized digital service of the United Nations Office for the Coordination of Humanitarian Affairs (OCHA), ReliefWeb Project, Glossary of Humanitarian Terms (Draft Version), NY, USA 2008. http://www.who.int/hac/about/reliefweb-aug2008.pdf , (Dzstr/ Humanitarian Relief - Brit) {813}