The regionality and seasonality of tornado trends in the United States

Abstract

Continued efforts to build human resilience to the impacts of tornadoes require updated knowledge of tornado occurrences as well as how their occurrence characteristics may be changing in time and varying by region. We have temporally and geospatially disaggregated annual tornado reports in the United States and revealed that significant, long-term decreases in tornado days from 1960 to 2022 have occurred over the months of June through August, primarily within the Southern Great Plains. In contrast, long-term increases in days of tornado outbreaks have occurred over this period, particularly within the Southeast U.S. and during warm- as well as cool-season months. There are indications that these dichotomous linear trends in tornado days and tornado outbreaks have relaxed over the most recent decade. Our study highlights the need to better understand the role of internal climate variability and anthropogenic forcing in modulating tornado activity.