A CLIMATOLOGY OF DERECHO-PRODUCING MESOSCALE CONVECTIVE SYSTEMS IN THE CENTRAL AND EASTERN UNITED-STATES, 1986-95 - PART I - TEMPORAL AND SPATIAL-DISTRIBUTION

In 1888, Iowa weather researcher Gustavus Hinrichs gave widespread con vectively induced windstorms the name ''derecho''. Refinements to this definition have evolved after numerous investigations of these system s; however, to date, a derecho climatology has not been conducted. Thi s investigation examines spatial and temporal aspects of derechos and their associated mesoscale convective systems that occurred from 1986 to 1995. The spatial distribution of derechos revealed four activity c orridors during the summer, five during the spring, and two during the cool season. Evidence suggests that the primary warm season derecho c orridor is located in the southern Great Plains. During the cool seaso n, derecho activity was found to occur in the southeast states and alo ng the Atlantic seaboard. Temporally, derechos are primarily late even ing or overnight events during the warm season and are more evenly dis tributed throughout the day during the cool season.