Spatiotemporal analysis of tornado exposure in five US metropolitan areas

Weather-related disasters and affiliated losses in the USA have amplified over time. However, prior research using normalization schemes on damage tallies suggests that weather hazard losses are not necessarily rising when inflation, changes in wealth, and growth in population are accounted. This study evaluates the latter factor, assessing if population changes and a sprawling development mode have led to increasing potential for tornado disasters in the USA. Specifically, this research shows where and how quickly tornado exposure is growing by appraising spatiotemporal trends in gridded population and housing unit data for five metropolitan statistical areas (MSAs). The macroscale risk to tornadoes is represented by tornado day climatology and is related to the exposure of the five MSAs, which include Atlanta, GA; Chicago, IL; Dallas/Fort Worth, TX; Oklahoma City, OK; and St. Louis, MO. Supplementing the macroscale investigation, an observationally derived, hypothetical violent tornado track is transposed on various development types in each MSA to determine the microscale changes in human and built-environment exposure. Results demonstrate increased exposure in all MSAs at both the macro- and microscale. Of the five MSAs studied, Dallas, TX, had the greatest potential for a tornado disaster due to the higher risk for tornado occurrence comingling with the amount of MSA exposure. These results reveal further that amplifying exposure is a major impetus behind intensifying severe weather impacts and losses.