Some interesting data about severe weather around Bloomington

We’ve been doing a bit of data science about historical storm events around Bloomington (specifically in Monroe County). We used NOAA’s Storm Events Database, which keeps track of severe storm events nationally going back into the 1950’s, and a tool called Tableau for creating some visualizations. The purpose here is to see if we can get some insight into the kinds of events we need to be most prepared for in Bloomington, and to see if there are any trends that can be identified in how things are changing.

The first graphic shows events that have happened in Monroe County since 1950, with the most frequent kind of reported event (thunderstorm wind) at the top. Darker blue indicates older reports (going back to the 1950’s) and lighter are more recent reports. Some interesting observations: effects of severe thunderstorms (wind, hail) dominate, followed by flooding and then tornadoes and winter storms. Note how tornadoes appear to have more recent than older reports: this could be due to an increase in tornado events, or it could be due to more accurate ways that we can now identify if tornadoes have occurred.


Here is a different way of looking at things: events by year. Each bar shows the total number of events, and the coloring is by event type. Interestingly there is very little data before 1970. Note the significant increase in number of events in the 2000’s. Again it is hard to tell if this reflects a change in weather patterns, or a change in reporting.

The last graphics are only concerned with frequency of event reports. But what about severity? One way to measure this is the amount of property damage. Here is a graph of property damage per year, colored by event type. Obviously, 2002 was a special year, when an unseasonal September long-track F3 tornado swept through Ellettsville, causing extensive damage.

If we remove the 2002 event, we can get a clearer picture of the types of events that are causing the most property damage. Interestingly, flooding and flash flooding are recurring culprits, along with other tornado events and a heavy snow event in 2004.

Finally, here is a map of event locations, where the color is the event type (same color categories as the other images above), and the size of the marker is proportional to the property damage.

So main conclusions here: floods and tornadoes are probably the biggest overall threats to us in Bloomington, at least by frequency of events and the amount of damage done.

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