Role of land cover boundaries on tornadogenesis in Indiana.

Tornadoes pose a significant threat to residents of Indiana due to a large relative frequency of events that is comparable to most states within classic Tornado Alley. Because of this threat weather forecasters must be very aware of atmospheric environments that lead to tornadogenesis. In some cases these environments are obvious; in others mesoscale variability conducive to tornadogenesis may not be easy to identify. As a result the purpose of this study is to determine if mesoscale variability along primary land-cover boundaries plays a significant role in the climatology of tornadogenesis in Indiana. This is accomplished by developing a set of spatial and temporal climatologies for all significant (F2 and greater damage) Indiana tornadoes from 1955 - 2001. These climatologies are used to determine if spatial distributions of tomadogenesis events are influenced over space and time by significant land-cover boundaries. Results of this research seem to suggest that land-cover boundaries play a role in the tornado climatology of Indiana, with large tornadogenesis frequencies in Lake County, Marion County, and along a corridor extending from central into southern Indiana. Urban heat island circulations seem to play a role in the Lake and Marion counties' frequency maxima, while non-classical mesoscale circulations (NCMCs) appear to contribute to the frequency maxima in southern Indiana.Department of GeographyThesis (M.S.