Severe local storms

ABSTRACT

Severe weather associated with thunderstorms (tornadoes, hail, high winds, and flash floods) is reviewed with emphasis on the processes that are responsible. The basis for forecasting severe thunderstorms in reviewed. The parts of the world that are most vulnerable to various kinds of severe weather and the nature of the threats are described. The current state of the climatology of severe thunderstorms and problems and importance of improving climatological information are described. The lack of high-quality climatological information makes it very difficult to determine differences in event occurrence during different periods of the El Niño-Southern Oscillation (ENSO) in most of the world and almost impossible to detect changes associated with global climate change. It is argued, however, that the threats from severe thunderstorms are generally underestimated in many parts of the world. In genera, the effects of severe local storms are concentrated in a small number of events. Death tolls and damage in "average "years are typically smaller than the totals from individual events in other years. As a result, maintaining public awareness and preparedness activities is difficult since the threat of rare, extremely damaging events, is small at any individual location and time. (AU)