I'm sure you've heard the term 'severe thunderstorm' mentioned many times in weather forecasts, but do you really know what it means?? There are also several other terms that are used to describe thunderstorms, including:
strong.....heavy.......gusty.....heavy and gusty, drenching, flooding, etc...etc....etc..

As you undoubtedly know, any thunderstorm can produce heavy, even flooding, rain, strong and potentially damaging wind and hail. Of course, all thunderstorms contain lightning, and all lightning is dangerous. I think most of us realize that, so when we hear that a 'thunderstorm' is in the forecast, we know that the weather can turn fierce in a short period of time. So, why then do we use so many terms to describe thunderstorms????? Well, it's a matter of emphasis. If we think the storms will be unusually heavy we might describe them as 'heavy' or 'flooding' to draw attention to that possibility. If we think wind could be unusually strong, perhaps strong enough to do damage, we might describe them as 'gusty' or 'strong', so that you will be aware of that possibility. The word 'severe' is different; it has a very strict meteorological definition...it means a storm that can produce winds of 58 mph or stronger, or hail 3/4 inch in diameter or larger. You might be surprised that the definition of severe says nothing at all about heavy rain or lightning. A storm could produce 4 or 5 inches of rain or more, and not strictly be classified as a severe thunderstorm.

Probably the most difficult thing to predict when it comes to thunderstorms is lightning. Of course, as mentioned above, all thunderstorms have lightning...after all...without lightning, there is no thunder. But some storms, even with a lot of rain, don't produce much lightning, and some storms without much rain produce a lot of lightning. And, all lightning strikes are not created equal. The average lightning strike produces a current of 10,000 to 20,000 amps and about 100 million volts, and has a negative charge. However, 4-5 percent of lightning strikes carry a positive charge and some 'super' bolts are many times more powerful than the garden variety. We do know that for lightning to form there must be some ice in the clouds, but at least to my knowledge it is not clear why one storm produces a tremendous amount of lightning and another only an occasional strike.

In any case, we will continue to fret over which words to use in our forecasts in order to convey to you, the consumer of weather information, the best picture of what we think the weather will do. It is something we really get a 'charge' out of, and we always try to be positive, even if the weather looks negative. Hopefully, we usually 'strike' the right chord and don't cause you to 'bolt' to another source of weather information.

If you would like to email me, please feel free to do so at sobel@accuweather.com

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