The National Weather Service considers a thunderstorm severe if the any of the following happens:
- the thunderstorm produces hail at least 1" in diameter
- winds in excess of 58 m.p.h. are observed
- a tornado is produced.
A SEVERE THUNDERSTORM WATCH means conditions are favorable for the development of thunderstorms that may turn severe.
A SEVERE THUNDERSTORM WARNING means severe weather is in the area, and you need to take safety precautions.
Here are some safety tips for when a thunderstorm is approaching:
- If you can hear thunder, you are close enough to the storm to be struck by lightning. Seek safe shelter immediately.
- DO NOT seek shelter in small sheds, under isolated trees, or in convertible automobiles. Move to a sturdy building or car.
- If lightning is occurring and a sturdy shelter is not available, seek shelter inside a hard top car and keep windows up.
- Stay away from water, this includes boats.
- Telephone lines and metal pipes can conduct electricity. Avoid using corded telephones or any electrical appliances. Cell phones are the safest to use during storms.
- Do not take a bath or shower.
- Power surges from lightning can overload compressors. Anything not attached to a surge protector should be turned off and unplugged.
- If you feel your skin tingle or your hair stand on end, squat low to the ground on the balls of your feet.
- If you are boating or swimming, get to land and find shelter immediately!
At any one moment nearly 1800 thunderstorms are occurring around the world and that amounts to over 16 million storms in a year. In the United States, it is estimated 100,000 thunderstorms occur each year with only about 10,000 actually reaching severe limits. A typical thunderstorm is 15 miles in diameter and lasts for about 30 minutes.