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What makes a thunderstorm severe?

Why are some storms classified as "severe," and when do we cut-in during programming to cover them?

I want to talk a little bit about thunderstorms. 

Every time we get a strong thunderstorm rolling through the region I get complaints from people wondering why I am not on TV covering it. It's the exact opposite of what happens when I go on TV and cover thunderstorms.

When I'm on TV, I get told that I should not be on and we should just run a crawl. 

Anyway, I wanted to talk a little bit about what constitutes a severe thunderstorm. 

With the thunderstorms that came through Friday evening from parts of the Eastern Shore through the middle peninsula and over to Williamsburg, there were a lot of bright colors on the radar with them. A couple of people from the middle peninsula wanted to know why we weren't on TV. 

As I mentioned, the reason is because we only go on TV for severe thunderstorms. 

So what makes a thunderstorm "severe"? 

Well, in this case, heavy rain moved through the area, and the live lightning tracker showed there was also quite a bit of lightning. In fact, there were 96 positive lightning strikes in 15 minutes out of a total of 129 lightning strikes. 

That's important because positive strikes have a tremendous amount of energy as compared to negative strikes. They shake your house more, they are louder, they are more prone to cause forest fires or hit homes and start fires so they sound a lot scarier. 

Another factor that gets people to call in all the time and wonder about coverage is the amount of rain or the fact that it is raining extremely heavily. 

In this case, you can see some spots had as much as 2.2" per hour. In terms of a rainfall rate, that is extremely heavy rainfall and looks almost like a biblical storm coming through. 

The only time you get any kind of a warning for heavy rain out of a thunderstorm is once it has already dropped a lot of rain. When that happens a flood warning can be issued, but there is no kind of a warning for a severe storm that is severe just because of its rainfall rate. 

The hail that was associated with the storm that came through Friday were generally around a-third-of-an-inch. Hail must be over 1" to be classified as severe. 

So the bottom line concerning thunderstorms: only two things can classify a storm as severe. 

First, winds must be over 60 miles per hour. Anything less and trees will not fall down, you might get some branches falling, but you typically will not get entire trees, which is why that is the criteria. 

The next criteria is hail. Hail must be 1" or larger in diameter because studies have found that anything smaller than that will not damage cars or windows of homes. 

There you have it. A complete explainer as to what makes a storm severe and why we do or do not cut-in over programming or commercials to cover it.

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