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Category: Project

Description: Storm reports show an upward trend in the power of tornadoes from longer and wider paths and higher damage ratings. Quantifying the magnitude of the increase is difficult given diurnal and seasonal influences on tornadoes embedded within natural variations and made worse by changes for rating damage. Here the authors solve this problem by fitting a statistical model to a metric of power during the period 1994--2016. They find an increase of 5.5\% [(4.6, 6.5\%), 95\% CI] per year in tornado power controlling for the diurnal cycle, seasonality, natural climate variability, and the switch to a new damage scale. A portion of the trend is attributed to long-term changes in convective storm environments involving dynamic and thermodynamic variables and their interactions. Increasing tornado power is occurring in environments where the effect of convective available potential energy is enhanced by increasing vertical wind shear.