Using data from the NOAA Storm Prediction Center, our GIS specialist Zoe Zaloudek created a map of tornado tracks in Illinois from 1950 to 2010. The tracks are color-coded from blue to red to purple for F0 to F5 tornado events. The map below gives a general idea of the tracks, the PDF file is at higher resolution so that you can see much more detail.
There are some outstanding features. Like earlier studies, central Illinois is the most active region of the state. There are relatively few tornadoes reported in the northwest and southeast corners of the state. It could be the terrain – more hills and woods makes it harder to see tornadoes. Or it could be that those areas are also less densely populated.
Another feature is the local “hot spot” in Kankakee and Will Counties, relative to surrounding counties. We see a similar pattern with heavy rainfall events so it is probably genuine, and not an artifact of the data collection.
We have noticed a few artifacts in the map and are working with SPC to get those resolved. For example, there are a few instances of the tracks forming a triangle.