The Future of Hazardous Convective Weather in the United States

Potential shifts in the United States climatology of hazardous convective weather (i.e., tornadoes, damaging wind, and severe hail) due to anthropogenic climate change are explored for the middle and end-of-the-21st century. Specifically, output from dynamically downscaled, convective-permitting simulations is used to examine convective peril proxies across three, 15-year epochs—1990-2005, 2040-2055, and 2085-2100—for both intermediate and pessimistic warming scenarios. An explicit approach is employed to define hazardous convective weather using a combination of simulated upward vertical velocity and reflectivity that meet specific thresholds. In response to enhanced greenhouse forcings and related change in fundamental severe storm ingredients, spatiotemporal changes in hazardous convective weather occur in the mid and end of twenty-first century periods compared to the historical epoch, including a lengthening of the severe season and increases in the overall frequency of perils. Results illustrate significant increases of severe weather perils across all future epochs, driven by higher frequencies in the spring and early summer seasons attendant with overall greater annual variability in synthetic reports. Increases in hazardous convective weather days are projected for the Mid and Deep South, Southern Plains, and Midwest in the spring and Midwest and Southeast during the summer, with slight decreases found in the Great Plains during the warm season. Results provide important insight into the changing hazardous convective weather landscape so that stakeholders, policy makers, and the public may mitigate and build resilience against future events.