A climatological analysis of drought and tornadic activity in the southeastern United States

The Intergovernmental Panel on Climate Change (IPCC) has indicated the probability of an acceleration of the water cycle due to climate change prompting more research on surface moisture feedbacks. Antecedent drought is hypothesized to reduce convection in the spring, possibly through soil moisture memory (forced by ridging) and subsequent atmospheric response. The relationship between Southeast tornadoes and drought is analyzed by quantifying the frequency of tornado day occurrence under antecedent drought conditions, understanding how antecedent drought is related to tornadic environments and the role of soil moisture memory, and determining if drought is influenced by the Bermuda High. Correlation analysis indicates fall/winter drought is associated with drought conditions in the spring, reduced convection, and below normal tornado activity. This research presents one of the first attempts to consider physical mechanisms that explain recent observational evidence of reduced tornado days following antecedent drought in the fall/winter seasons.