Diagnosing the Conditions for Tornadic Outbreaks and Their Effects on Human Population Centers

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Sunday, 4 January 2015
Omar C. Gates, University of Michigan, Ann Arbor, MI

Tornadic outbreaks are violent weather phenomena that result in significant loss of property and life in many communities annually. A question central to ongoing research on the drivers and impacts of tornadic outbreaks is whether the frequency or intensity of these events might change in an altered climate state. Regional climate models (RCMs) and global circulation models (GCMs) are the primary tools used to assess the effects of climate change, but employ grid resolutions too coarse to directly simulate tornado-producing convective storm systems. In contrast to direct simulation of severe convective storms, it may be sufficient for RCMs and GCMs to replicate the conditions that support the development of tornadoes. The purpose of this research is to establish the large scale environmental conditions associated with tornadic outbreaks, and to determine whether coarse resolution models are capable of realistically simulating them. If coarse resolution models can be shown to reproduce past convective environments, it may be possible to use them to diagnose future tornadic outbreaks.

In addition to understanding the conditions associated with tornadic outbreaks, another area of interest is determining which cities are more prone to such an environment in the future. When used in combination with RCMs and GCMs, Geographic Information Systems (GIS) add more understanding as to where possible tornado activity may occur, and the effects it would have on human populations in the affected cities. In this presentation, previous severe weather reports from the Storm Prediction Center (SPC) are assessed in order to understand which areas are most at risk of tornado activity, and whether these findings correlate to areas where large human population centers are located. The usage of reports associated with tornadoes, high winds, and hail, as well as census block data, enables further understanding of the cities that are more at risk during tornado activity based on human populations and socioeconomics. By looking at the socioeconomic data from potentially affected cities, it possible to see which areas can or cannot readily recover from tornado outbreak events in the future. This study is designed to lead to improved understanding of tornadic outbreaks and the risk assessment of cities that are more likely to endure hazardous environments in the future.