Abstract
In recent years, many meteorologists have claimed that ‘tornado alley’ has shifted over the last decades toward the east. We wanted to see if this claim holds true. We searched online for databases containing information on all US and all Canada tornadoes. By visualizing the data, we were able to find some trends in rating and the number of tornadoes over time. Using a program we wrote in R, we calculated the geographical average for tornadoes for each year. We also weighted this average by the rated magnitude of each tornado and by the number of deaths from each tornado. We then used ArcGIS to map the 5-year running average tornado centers for these datasets. We produced heatmaps using Kernel Density analysis in ArcGIS Pro to show tornado hotspots.We found that the geographical center for tornadoes has shifted east from southern Missouri to southeastern Missouri. Our weighted-by-magnitude map appears very similar to the non-weighted map, while the weighted-by-deaths map shows a shift from Southeast Missouri to Northern Alabama. We conclude that tornadoes are less concentrated in the Western Plains than they used to be and seem to be showing up more in Dixie Alley. We suggest that further research be conducted to examine how significant this shift is and why it is occurring.
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Geographic Trends in North American Tornado Risk: A 75 Year Analysis
In recent years, many meteorologists have claimed that ‘tornado alley’ has shifted over the last decades toward the east. We wanted to see if this claim holds true. We searched online for databases containing information on all US and all Canada tornadoes. By visualizing the data, we were able to find some trends in rating and the number of tornadoes over time. Using a program we wrote in R, we calculated the geographical average for tornadoes for each year. We also weighted this average by the rated magnitude of each tornado and by the number of deaths from each tornado. We then used ArcGIS to map the 5-year running average tornado centers for these datasets. We produced heatmaps using Kernel Density analysis in ArcGIS Pro to show tornado hotspots.We found that the geographical center for tornadoes has shifted east from southern Missouri to southeastern Missouri. Our weighted-by-magnitude map appears very similar to the non-weighted map, while the weighted-by-deaths map shows a shift from Southeast Missouri to Northern Alabama. We conclude that tornadoes are less concentrated in the Western Plains than they used to be and seem to be showing up more in Dixie Alley. We suggest that further research be conducted to examine how significant this shift is and why it is occurring.