Historical trends and future-climate projections of tornado activity in the United States

Robert J. Trapp

Professor and Head, Department of Atmospheric Sciences, University of Illinois at Urbana-Champaign

The presentation will begin with an examination of historical data, which if used carefully are found to reveal the existence of long-term trends in the intensity and frequency of tornadoes. These and other tornado characteristics are intimately linked to characteristics of the parent tornadic-thunderstorm, which in turn depend to varying degrees on the larger-scale meteorological environment. Accordingly, a brief overview of how tornadoes should relate to their larger-scale environment will be provided, followed by some simple arguments on how changes to the environment might result in changes in tornado activity. Finally, global and regional climate model simulations will be consulted to determine if future impacts are to be expected; a discussion of the means in which these simulations are “downscaled” to thunderstorm (and smaller) scales will also be included.