Most of the United States is relatively safe when it comes to severe weather. Of course, we think of Oklahoma and Texas as being prime spots for tornadoes. But a new map shows us the average amount of time spent in a weather warning per county. Daryl Herzmann of Iowa State University released some great maps this week. Take a look!
First, here is the average time spent in a Severe Thunderstorm Warning.
Of course, the higher likelihood for severe thunderstorms lies in the Tornado Alley state of Oklahoma. But notice the maximum over Eastern Tennessee and even Northern Ohio. It may be a little difficult to see the actual location of states because the dark black lines in this map represent the borders of the National Weather Service offices. Here in Northern Illinois and Southern Wisconsin, we are serviced by three different offices, Milwaukee-Sullivan, Quad Cities-Davenport, and Chicago-Romeoville.
Next up, the map showing the average minutes of the year spent in a Tornado Warning:
A few things on this map stand out. First, the larger counties within a tornado-prone zone have a higher chance of being within a warning polygon. Of note is the number of minutes in McLean Co., IL (Bloomington-Normal) which is the largest county in Illinois in bright red compared to Putnam Co., IL (North of Peoria) which is blue.
Daryl went further and took square kilometers into account with the following map. This one is telling! It shows the highest likelihood of a Tornado Warning (not necessarily a full-fledged, on-the-ground tornado) to be in Mississippi.
So, while we may think of Tornado Alley being Texas and Oklahoma, the higher threat of tornadoes may reside in the Deep South…at least looking at the data over the past 20 years.
Finally, for your viewing pleasure? The map for Flash Flood Warnings per county. It’s easy to see the highest probabilities for flash flooding in the past 20 years are in Southern Missouri and in the Desert Southwest.
This post was written by Eric Sorensen on April 10, 2014