Thunderstorms can bring heavy rains, flash flooding, tornadoes, strong winds, lightning, and hail. Flash floods/floods are the number one killer associated with thunderstorms, with nearly 140 fatalities a year.

Although thunderstorms in this area are less likely to spawn tornadoes than elsewhere in the United States, most wind damage is from "straight-line" rather than tornadic winds. "Downbursts," a type of straight-line wind, can cause damage equivalent to a strong tornado.


Lightning occurs with all thunderstorms. Its electrical charge and intense heat can electrocute on contact, cause electrical failures, split trees, and ignite structure and brush fires.


Hail associated with thunderstorms can be smaller than peas or as large as softballs and can be very destructive. While some thunderstorms can be seen approaching, others hit without warning.

Danger Signs

It is important to learn to recognize the danger signs and plan ahead. When thunderstorms are forecast or skies darken, look and listen for:

  • Dark, towering, or threatening clouds
  • Increasing wind
  • Flashes of lightning
  • The sound of thunder

When a Thunderstorm Is Approaching

At Home

  • Secure outdoor objects such as lawn furniture that can blow away and cause damage or injury.
  • Bring lightweight objects inside.
  • Listen to a battery-operated radio or television for the latest storm information.
  • Avoid bathtubs, water faucets, and sinks because metal pipes can transmit electricity.
  • Pets are particularly vulnerable to hail and should be brought inside.

If Outdoors

  • Attempt to get into a building or car. If no structure is available, get to an open space and squat low to the ground as quickly as possible.
  • The less contact you have with the ground, the better.
  • Be aware of potential for flooding in low-lying areas. Avoid tall objects such as towers, tall trees, fences, telephone lines, and power lines.
  • Stay away from natural lightning rods such as golf clubs, tractors, fishing rods, bicycles, and camping equipment.

What Is a Severe Thunderstorm

A thunderstorm is considered severe if it produces hail at least 0.75-inch in diameter, winds of 59 miles per hour or higher, or tornadoes.

The Difference Between a Watch & a Warning

A severe thunderstorm watch is issued by the National Weather Service when the weather conditions are such that a severe thunderstorm is likely to develop. A severe thunderstorm warning is issued when a severe thunderstorm has been sighted or indicated by weather radar. At this point, the danger is very serious and everyone should go to a safe place, turn on a battery-operated radio or television, and wait for further information.

Helpful Tips

Remember to help neighbors who may require special assistance (infants, senior citizens, and people with disabilities).

If you are driving after a thunderstorm, be vigilant for downed branches and power lines or other debris lying in the road. Do not touch or drive over downed lines.

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