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Storm Stats: Thunderstorms & Lightning

Know Your Thunderstorm Risks, Alerts, and Safe Locations


Storm Stats: Thunderstorms & Lightning

What is a Severe Thunderstorm?

Severe thunderstorms are thunderstorms having winds of at least 58 mph, hail at least 1 inch in diameter, and the capability of producing tornadoes. They occur most often during the spring and summer months during the afternoon and evening hours. Main hazards include high winds and lightning.

What is Lightning?

Lighting is the rapid discharge of electricity from the buildup of positive and negative charges between cloud and ground, respectively. Types of lightning include:
  • Intra-cloud
  • Cloud-to-ground
  • Ground-to-cloud

Determining Storm Distance

Thunder (the sound made by a lightning flash) travels approximately one mile per 5 seconds. This ratio can be used to estimate how many miles away a thunderstorm may be. Simply count the seconds between seeing a lightning flash and hearing a thunderclap and divide by 5.

Stay Informed

Depending on storm severity and the threat to your region, the National Weather Service will issue one of the following statements:

A severe thunderstorm watch is issued when conditions are favorable for severe thunderstorm formation. Watches last for approximately 4-8 hours.

A severe thunderstorm warning is issued when a severe thunderstorm is imminent or occurring based on radar or weather spotter reports. Warnings usually last for about 1 hour.

Take Action before the Storm

If a severe thunderstorm warning is issued, take shelter immediately!

Indoors: Because lightning can travel through air, plumbing systems, and phone lines, stay away from windows, doors, sinks, and off of land-line phones. You may also wish to turn off and/or unplug televisions, computers, and other electronics in order to protect against electrical surges. Stay indoors until 30 minutes after the final thunderclap is heard.

In a vehicle: Any fully enclosed, metal-topped car is considered a “safe vehicle.” (The metal frame acts as a conductor of electricity, and if hit, will channel the lightning strike away from your body.) While inside, do not touch electrical devices.

Outdoors: There is NO safe location when outdoors during a thunderstorm. Seek shelter immediately in a nearby enclosed building! If this isn’t an option, reduce your risk of a lightning strike by avoiding open fields, hills or ridgetops, tall trees, water, and metal objects.

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