In a stimulating presentation, Wurman et al. (2007, hereafter W2007) have produced an interesting estimate of the possible effects of violent tornadoes in urban areas by making models of the wind field based on mobile Doppler radar observations. As part of that effort, they have estimated death tolls associated with those modeled wind field, arriving at estimates from 13,000 up to 63,000 in Chicago, Illinois. Given that the highest death toll in a tornado in U.S. history is 695 in the Tri-State tornado of 1925, and that the last death toll of greater than 100 was in 1953, the validity of these estimates is of some concern. We are certainly in favor of raising the level of awareness of the potential for large casualty figures in future tornadoes. The concentration of our population in urban areas, combined with urban sprawl, has increased the threat of large fatality figures if a large, violent, long-track tornado were to hit a major metropolitan area. Planning for such a catastrophic event requires an estimate of the potential impacts. We fear, however, that the enormity of the fatality estimates in W2007 might discourage emergency managers from planning for such an event, because they would simply be overwhelmed by such a disaster.
Find the article at the American Meteorological Society.