Tornadoes in the USA are concentrating on fewer days, but their power dissipation is not

Abstract

The Gini coefficient, Palma ratio, and the ratio of the percentage of tornadoes occurring on days with 20+ tornadoes to the percentage of tornadoes occurring on days with 1-9 tornadoes were used to measure the concentration of tornadoes in the USA for each year over the period 1954-2017. The Gini coefficient and Palma ratio were also used to measure the concentration of tornado power. All three metrics illustrate that most tornadoes are concentrated on relatively few days and that power is even more concentrated. Trend tests illustrate that tornadoes are becoming more concentrated over time, but the power dissipated by tornadoes is becoming less concentrated. Despite the declining trend, most of the power dissipated by tornadoes remains highly concentrated on relatively few days.