Typing Tornadoes by Storm Mode in the Southeast United States: 1996–2017

Existing work has noted three major, radar-derived, storm modes associated with tornadoes: supercells, quasi-linear convective systems, and tropical systems. We examine the long-term frequency and seasonality of each storm mode between 1996 and 2017 in the Southeast United States. The Southeast is chosen as a focus for this work due to its well-known and unique combination of tornado vulnerability and exposure. Expanding our knowledge of the radar presentation of tornado producing thunderstorms in this region could assist in the operational interpretation of these events. First, we generate a climatology of EF1+ tornadoes (1996 - 2017) in the study area (Texas, Arkansas, Oklahoma, Louisiana, Mississippi, Alabama, Georgia, Tennessee, and Florida). Next, we analyze the seasonality and annual frequency of all tornadoes and tornadoes by storm mode. Finally we examine how many tornado days are in each state by storm mode, and determine if storm mode influences a clustering of tornado reports. These results will help in determining the frequency of different storm modes as well as help us have a deeper understanding of tornado climatology in the Southeast.