Examination of the Predictability of Nocturnal Tornado Events in the Southeastern United States

The southeast United States is particularly susceptible to dangerous tornado impacts. Tornadoes that occur at night pose particularly dangerous societal risks, and these risks are amplified across the southeastern United States. This presentation addresses some of the characteristics distinguishing the convective environment accompanying these events occurring during the 0300-1200 UTC (nocturnal) time frame between the months of November through May. Using the Statistical Severe Convective Risk Assessment Model (SSCRAM), we determine how well convective parameters explain the potential for these tornadoes. This study compares conditional tornado probabilities across the Southeast during November–May nocturnal hours to those probabilities for all other November–May environments across the contiguous United States. We demonstrate that the predictability of Southeast, November–May, nocturnal tornadoes is generally similar to that within other regimes across the contiguous United States. However, selected ranges of multiple parameters are associated with slightly better predictability for the nocturnal Southeast regime. Additionally, this study assesses conditional November–May nocturnal tornado probabilities across a coastal domain embedded within the Southeast. Nocturnal coastal tornado predictability is shown to generally be lower than the other regimes. All of the differences highlight several forecast challenges, which we analyze in detail.