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Thunderstorms, like pies, come in different varieties. A typical thunderstorm is as common as an apple or cherry pie. But a severe thunderstorm is like pie a la mode, a piece of pie with a little something extra on top. A severe thunderstorm is a violent and powerful thunderstorm that is capable of causing a lot of damage. 
 
A severe thunderstorm has special qualities that make it severe. A severe thunderstorm must have one or more of the following: 
 
  • 0.75 in. diameter or larger-sized hail 
  • 58 mph winds or stronger 
  • Tornadoes or funnel clouds 

    • Weather conditions have to be precise for a severe thunderstorm to develop. Besides the typical ingredients needed for a thunderstorm to be created, a severe thunderstorm needs a steady supply of moisture. And it needs the presence of a dry line, a boundary between a warm air mass and a cold air mass. The movement of a dry line forces moist air into the atmosphere, creating updrafts and forming thunderstorms. 

    One kind of severe thunderstorms is called a supercell. A supercell has a rotating, long-lived, intense updraft that gives it incredible power. Although not very common, they produce a relatively large amount of severe weather, including extremely large hail, damaging straight-line winds, and practically all violent tornadoes. 

    		  
    Thunderstorm picture 
     
     
     


    Find out more about dry lines and why they help create thunderstorms by visiting here. 
     
    Find out about some of the hazards of thunderstorms - next!
     
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