Anthropogenic Influences on Severe Storms in the Midwest

Severe storms produce high-impact extreme weather events, such as tornadoes, that can cause billions of dollars in damages. As the population increases, more people will live in regions that are susceptible to such extreme weather events, thus underscoring the importance of understanding severe storms in a changing climate. Previous studies that have examined the effects of climate change on severe storms and tornadoes have faced multiple sources of uncertainty, including inconsistencies in the observational record. In this study, we address this uncertainty by using the Weather Research and Forecasting (WRF) model at convection-permitting resolution to examine how two tornado-producing severe storms respond to changes in the climate both from pre-industrial to present, and into the future. We choose two severe storm events over Missouri that led to: (1) The New Year’s Eve 2010 tornado outbreak near Ft. Leonard Wood, and (2) the May 2011 tornado in Joplin. The control simulation consists of ensembles of WRF hindcasts of these two events forced by the historical surface and lateral boundary conditions as they actually occurred. To examine how the severe storms have responded to climate change since the pre-industrial period, we repeat the WRF simulations by perturbing the boundary conditions to reflect similar synoptic conditions, but in a pre-industrial mean climate state. To examine how the severe storms could respond to future climate change, we repeat the hindcasts using boundary condition perturbations corresponding to the end of the twenty-first century under the RCP4.5, RCP6.0, and RCP8.5 emission scenarios. We plan to analyze storm characteristics including precipitation, wind, convective available potential energy, and convective inhibition, as well as indicators of tornado activity, such as storm relative helicity. Comparing the results of the WRF experiments will provide a better understanding of how tornado-producing severe storms are affected by future climate change as well as by climate change over the past century.