The Space Time Structure of Extreme Storm Rainfall in the Southern Plains

Abstract

The space?time structure of extreme storm rainfall in the southern plains is examined through empirical analyses of radar and rain gauge data. Two networks of rain gauge data are utilized: a collection of more than 200 rain gauges in the southern plains from the National Weather Service (NWS) climatological network and a network of 168 rain gauges from the Southern Great Plains Research Watershed covering an area of approximately 3000 km2. The NWS climate network is useful for analysis of extreme rainstorms that cover relatively large areas, whereas the experimental network is useful for analysis of heavy isolated rainstorms that have been described as affecting areas less than 1000 km2 and having 1?4-h rainfall totals exceeding 75 mm. Analyses of rain gauge data from the two networks are used to characterize seasonality and spatial scale of extreme rainstorms. It is shown that there are pronounced spring and fall peaks in extreme rainstorm occurrence and that these peaks depend on the spatial scale of observations The space?time structure of extreme storms is examined through analyses of radar and rain gauge data for four storms that represent distinctive modes of organization of extreme rainstorms in the southern plains. These analyses are used to characterize and contrast the space?time structure of linear and chaotic convective systems, weak and strong dynamic forcing events, and spring and fall events. Analyses of these four events are augmented by climatological analyses of extreme rainstorms from the two rain gauge networks. The analyses presented in this paper are motivated by problems of engineering hydrometeorology and flood hazard assessment.