While the core of severe weather season is still several months away... after all in only a few days winter will officially begin... the National Weather Service is making a change to its official definition of a severe thunderstorm.
As you probably know... when a Severe Thunderstom Warning is issued, severe thunderstorms are occurring or have been spotted or detected by radar. The National Weather Service (NWS) defines a severe thunderstorm as having winds 50 kts (58 mph), hail greater than ¾" in diameter (about dime-sized) or a storm that spawns a tornado.
Beginning January 5, 2010, the minimum size for severe hail nationwide increases to one inch (quarter-size) diameter. There will not be a change to the wind gust criterion of 58 mph or of course a tornado.
Why the change? It's based on research data showing significant damage does not occur until the size of hail reaches 1 inch (quarter-size) diameter. The concern has been that the number of severe thunderstorm warnings issued for thunderstorms with penny-size and nickel-size hail might make the public less sensitive to taking protective cover during a severe thunderstorm warning.
The National Weather Service is hopeful this change will make warnings more meaningful and carry more weight when you get them.
Severe thunderstorm warnings are issued by local NWS offices. The size of the warning area is generally the size of one or two counties and usually lasts less than an hour.
When a severe thunderstorm warning is issued... it is recommended you find shelter in a sturdy building and stay away from windows, doors and outside walls.
Email
Facebook
Google
Twitter
Favorites
More
Advertisement