When thunder roars, it's time to go indoors. But does hearing thunder or seeing lightning make a storm "severe"? No. 

During severe weather season, it's common to hear meteorologists talk about a Severe Thunderstorms Warning. But in order for a storm to be classified as severe (by the National Weather Service), it must have one of two things. Do you know what they are?
Some think it's the amounts of rain, others think it has to do with the amount of lightning. Neither of those are a factor.

In this short video, Chief Meteorologist JD Rudd tells you what it takes--and what it does not--to make a storm count as "severe".