Spatial and Temporal Patterns of Drought Persistence in the Southeastern United States

Previous literature suggests that droughts in the southeast U.S. do not persist from one season to the next, at least not in a predictable manner. However, limited work has been done to explicitly test drought persistence in the region. The purpose of this study is to investigate drought persistence in the southeastern United States. Three month Standardized Precipitation Index (SPI) between 1895 and 2011 is obtained from the National Climate Data Center. The climate division SPI is used to define seasonal precipitation anomalies in the southeastern United States. Spatial and temporal patterns of seasonal drought persistence are examined by calculating the probability of drought occurring in subsequent seasons given the presence of current drought. A logistic regression model is also developed using current season SPI to determine the probability of drought occurrence in subsequent seasons. Significant spatial and temporal variability in drought persistence exists across the region. While no climate division exhibits especially high probabilities of drought persistence, in agreement with limited previous research, the central Gulf Coast states of Alabama, eastern Mississippi, and western Georgia show higher probabilities relative to the surrounding areas across all seasons. Calculated probabilities suggest little persistence along the east coast. Results from the logistic regression model show an overall good fit, but with mixed results, demonstrating the lack of strong drought persistence in the region. Future research will examine the influence of Atlantic teleconnections on spatiotemporal patterns of drought persistence in the region.