Tornado Intersection Project

by Jason Palleria - Student Volunteer

Although the exact count varies, Oklahoma City is the #1 city in the tornado count game, as reported by Mike Branick of the Norman, Oklahoma National Weather Service office. He recorded 123 tornadoes crossing within the Oklahoma City city limits.

I decided to find out the same for Wisconsin, therefore I compiled information about tornado paths to see where tornado paths intersected in Wisconsin.  I only concentrated on torndoes of F2 strength or stronger.Tornado Intersection Project

As you can see, there is a lot of data about the paths of tornadoes through Wisconsin and how these paths intersect. So for this project, I wanted to investigate these areas of intersection. In ArcGIS (a Geographic Information System program), there is a tool that will locate all of the intersecting lines. From this, I located where these intersections are in reference to a city, town or body of water. Below, are multiple maps of tornado path intersections. There are many places within the state of Wisconsin, or just in the Milwaukee/Sullivan County Warning Area (CWA), that have had at least two tornadoes cross paths.   

All Intersections

This is a map of tornado paths and intersections around the CWA for the Milwaukee/Sullivan office.  Please note there seems to be a higher frequency of intersections in the western and northern parts of the CWA. This could lead to a futher study about why these areas have a higher frequency of tornados while southeastern WI has much less.


Below, are the different tornado strengths and their paths broken down into individual maps, showing points of intersection of the same tornado strength. Note that there are many more instances of F2 tornadoes than any other strength, resutling in more intersections of F2 tornadoes. Only one place, discussed below, has been hit by two F4 tornadoes. Also, nowhere in Wisconsin has been hit by more than one F5 tornado. This makes sense since there are 4 events within the range of my data.

F2 tornados  F3 Tornados

F4 Tornados  F4 Tornados

As you can see above, there are many intersections of tornado paths, many of which have had varied strength tornadoes move through. Two of the more interesting areas are near the city of Pewaukee just west of Milwaukee and near Lake Mead in northwest Wisconsin. These areas had at least 3 intersecting points over a very small area (roughly 1-2 miles).

Pewaukee  Lake Mead

Another interesting area is in northwest Wisconsin just northwest of Lake Eau Claire. Here, two F4 tornadoes passed through. This first occurred on May 10th 1953, where 4 injuries were reported.  The second occurred on June 6th 1958, where 4 deaths and 3 injuries were reported.

Lake Eau Claire

As a student volunteer, one of our requirements was to complete a top news story/research project of anything of our interest. For my topic, I wanted to choose a tornado related topic. I ended up picking paths of tornadoes through the Wisconsin area and where have these paths intersected. I ended up getting very interesting results. For this project, I needed data on paths of tornados. This data was given to our office from the National Climatic Data Center (NCDC). To plot this data I used a Geographic Information System (GIS) program called ArcGIS. This program ingested data about the positions of the tornado tracks (lat and lon coordinates) and plotted the data using a certain coordinate system. An image of the state of WI was used for the background with the counties outlined.

Please note that my data is from 1950-2002 and the F-scale was in place during this time. The EF-scale was not implemented until 2007. Also, this data only contains information on F2 tornadoes and greater because I only wanted to use the most significant tornados.

Unfortunately, I am not able to plot the date of each tornado because this will make the map too crowded. For further information on the dates please visit the website: - Tornado Maps and Database.  

Overall, this project was fairly simple but the results are very interesting. This information could be used by surveyors and other county officials to assess risks to areas of frequent tornado visits. Further work could be done with this project using more recent data. The tornado paths used were from 1950-2002, but I did find further information on more tornadoes. Unfortunately, I was not able to display this data.

Jason Palleria - Student Volunteer

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