The Hydrometeorological Environment of Extreme Rainstorms in the Southern Plains of the United States

Abstract

Convective storms are commonplace in the southern plains of the United States. Occasionally, convective storms produce extreme rainfall accumulations, causing streams and rivers to flood. In this paper, we examine the hydrometeorological environment associated with these extreme rainstorms. Datasets used include hourly precipitation data from more than 200 stations, upper-air data, and daily weather maps. The seasonal distribution of extreme rainstorms in the southern plains has pronounced peaks in late spring and early fall. Moisture availability and convective instability are higher than climatological averages during spring and fall extreme rainstorms, but nearer their averages during summer extreme rainstorms. Although high levels of moisture and convective instability are most common in the summer, the dynamic forcings that can initiate and focus convection are weak. It appears that late spring and early fall are the most likely times for extreme rainstorms because anomalously high levels of moisture and convective instability often encounter strong dynamic forcings.