David M. Brommer Department of Geography University of Alabama

1. Spatial Characterization of Storm Internal Precipitation Distribution for the Southeastern United States (1980-2009) David M. Brommer Department of Geography University of Alabama

2. Introduction • Quantifying the character of precipitation • Precipitation amount • Precipitation timing • Precipitation intensity • Precipitation modeling • Why? • Capture the variability in precipitation to plan, design, and manage water resources

3. Data and Methods • Hourly Precipitation Dataset 3240 • National Climatic Data Center • 6,500 primary, secondary and cooperative weather stationsfrom 1900 to present • Reduced to 143 stations • Primary (first-order) stations • Precipitation measured to 0.254 mm hr-1 (0.01 inch) • No data gaps from 1980 – 2009 • Precipitation events last at least three hours (no events of one- or two-hour duration included)

4. Data and Methods • Why three-hour or longer events? • Statistical tests required a minimum of three data points • Air mass (pulse)-type thunderstorms removed • Assess the variability within longer-duration precipitation occurrences • 149,197 individual, three-hour or longer events identified • To assess internal variability, skewness and kurtosis are used

5. * Precipitation events three hours or longer

7. Precipitation Skewness

8. Precipitation Kurtosis

9. Average number of maxima (peaks) within the precipitation disribution

10. Conclusion • Internal character of precipitation across the U.S. highly variable • Especially the Southeast • Seasonal variability, too • Convective events, initially, play a roll in determining internal distribution • Future work? • Seasonal signal (cold-season, in paticular) • Incorporate additional stations • 15-minute data?