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Severe Weather

Thunderstorms and Lightning

All thunderstorms are dangerous. Every thunderstorm produces lightning. In the United States, an average of 300 people are injured and 80 people are killed each year by lightning. Although most lightning victims survive, people struck by lightning often report a variety of long-term, debilitating symptoms. Other associated dangers of thunderstorms include tornadoes, strong winds, hail, and flash flooding. Flash flooding is responsible for more fatalities—more than 140 annually—than any other thunderstorm-associated hazard.

Dry thunderstorms that do not produce rain that reaches the ground are most prevalent in the western United States. Falling raindrops evaporate, but lightning can still reach the ground and can start wildfires.

Facts About Thunderstorms

  • They may occur singly, in clusters, or in lines.
  • Some of the most severe occur when a single thunderstorm affects one location for an extended time.
  • Thunderstorms typically produce heavy rain for a brief period, anywhere from 3 0 minutes to an hour.
  • Warm, humid conditions are highly favorable for thunderstorm development.
  • About 10 percent of thunderstorms are classified as severe—one that produces hail at least three-quarters of an inch in diameter, has winds of 58 miles per hour or higher, or produces a tornado.

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Facts About Lightning

  • Lightning’s unpredictability increases the risk to individuals and property.
  • Lightning often strikes outside of heavy rain and may occur as far as 10 miles away from any rainfall.
  • "Heat lightning" is actually lightning from a thunderstorm too far away for thunder to be heard. However, the storm may be moving in your direction!
  • Most lightning deaths and injuries occur when people are caught outdoors in the summer months during the afternoon and evening.
  • Your chances of being struck by lightning are estimated to be 1 in 600,000, but could be reduced even further by following safety precautions.
  • Lightning strike victims carry no electrical charge and should be attended to immediately.

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Know Your Thunderstorms and Lightning Terms

Familiarize yourself with these terms to help identify an thunderstorm hazard:

Severe Thunderstorm Watch
Tells you when and where severe thunderstorms are likely to occur. Watch the sky and stay tuned to NOAA Weather Radio, commercial radio, or television for information.

Severe Thunderstorm Warning
Issued when severe weather has been reported by spotters or indicated by radar. Warnings indicate imminent danger to life and property to those in the path of the storm.

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What to Do Before a Thunderstorm

To prepare for a thunderstorm, you should do the following:

  • Remove dead or rotting trees and branches that could fall and cause injury or damage during a severe thunderstorm.
  • "If thunder roars, go indoors" because no place outside is safe when lightning is in the area. We want everyone to stay indoors until 30 minutes have passed after they hear the last clap of thunder.

Summary of Lightning Safety Tips for Inside the Home

  • Avoid contact with corded phones

  • Avoid contact with electrical equipment or cords. If you plan to unplug any electronic equipment, do so well before the storm arrives.

  • Avoid contact with plumbing. Do not wash your hands, do not take a shower, do not wash dishes, and do not do laundry.

  • Stay away from windows and doors, and stay off porches.

  • Do not lie on concrete floors and do not lean against concrete walls.

The following are guidelines for what you should do if a thunderstorm is likely in your area:

  • Postpone outdoor activities.
  • Get inside a home, building, or hard top automobile (not a convertible). Although you may be injured if lightning strikes your car, you are much safer inside a vehicle than outside.
  • Remember, rubber-soled shoes and rubber tires provide NO protection from lightning. However, the steel frame of a hard-topped vehicle provides increased protection if you are not touching metal.
  • Secure outdoor objects that could blow away or cause damage.
  • Shutter windows and secure outside doors. If shutters are not available, close window blinds, shades, or curtains.
  • Avoid showering or bathing. Plumbing and bathroom fixtures can conduct electricity.
  • Use a corded telephone only for emergencies. Cordless and cellular telephones are safe to use.
  • Unplug appliances and other electrical items such as computers and turn off air conditioners. Power surges from lightning can cause serious damage.
  • Use your battery-operated NOAA Weather Radio for updates from local officials.

Avoid the following:

  • Natural lightning rods such as a tall, isolated tree in an open area.
  • Hilltops, open fields, the beach, or a boat on the water.
  • Isolated sheds or other small structures in open areas.
  • Anything metal—tractors, farm equipment, motorcycles, golf carts, golf clubs, and bicycles.

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What to Do During a Thunderstorm

If you are: Then:
In a forest Seek shelter in a low area under a thick growth of small trees.
In an open area Go to a low place such as a ravine or valley. Be alert for flash floods.
On open water Get to land and find shelter immediately.
Anywhere you feel your hair stand on end (which indicates that lightning is about to strike) Squat low to the ground on the balls of your feet. Place your hands over your ears and your head between your knees. Make yourself the smallest target possible and minimize your contact it the ground. DO NOT lie flat on the ground.

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Tornado

Tornadoes are nature’s most violent storms. Spawned from powerful thunderstorms, tornadoes can cause fatalities and devastate a neighborhood in seconds. A tornado appears as a rotating, funnel-shaped cloud that extends from a thunderstorm to the ground with whirling winds that can reach 300 miles per hour. Damage paths can be in excess of one mile wide and 50 miles long. Every state is at some risk from this hazard.

Some tornadoes are clearly visible, while rain or nearby low-hanging clouds obscure others. Occasionally, tornadoes develop so rapidly that little, if any, advance warning is possible.

Before a tornado hits, the wind may die down and the air may become very still. A cloud of debris can mark the location of a tornado even if a funnel is not visible. Tornadoes generally occur near the trailing edge of a thunderstorm. It is not uncommon to see clear, sunlit skies behind a tornado.

The following are facts about tornadoes:

  • They may strike quickly, with little or no warning.
  • They may appear nearly transparent until dust and debris are picked up or a cloud forms in the funnel.
  • The average tornado moves Southwest to Northeast, but tornadoes have been known to move in any direction.
  • The average forward speed of a tornado is 30 MPH, but may vary from stationary to 70 MPH.
  • Tornadoes can accompany tropical storms and hurricanes as they move onto land.
  • Waterspouts are tornadoes that form over water.
  • Tornadoes are most frequently reported east of the Rocky Mountains during spring and summer months.
  • Peak tornado season in the southern states is March through May; in the northern states, it is late spring through early summer.
  • Tornadoes are most likely to occur between 3 p.m. and 9 p.m., but can occur at any time.

What is the history of tornados where I live?

Know Your Tornado Terms

Familiarize yourself with these terms to help identify a tornado hazard:

Tornado Watch
Tornadoes are possible. Remain alert for approaching storms. Watch the sky and stay tuned to NOAA Weather Radio, commercial radio, or television for information.

Tornado Warning
A tornado has been sighted or indicated by weather radar. Take shelter immediately.

What to do Before a Tornado

Be alert to changing weather conditions.

  • Listen to NOAA Weather Radio or to commercial radio or television newscasts for the latest information.
  • Look for approaching storms
  • Look for the following danger signs:
    • Dark, often greenish sky
    • Large hail
    • A large, dark, low-lying cloud (particularly if rotating)
    • Loud roar, similar to a freight train.

If you see approaching storms or any of the danger signs, be prepared to take shelter immediately.

What to Do During a Tornado

If you are under a tornado WARNING, seek shelter immediately!

If you are in: Then:
A structure (e.g. residence, small building, school, nursing home, hospital, factory, shopping center, high-rise building) Go to a pre-designated shelter area such as a safe room, basement, storm cellar, or the lowest building level. If there is no basement, go to the center of an interior room on the lowest level (closet, interior hallway) away from corners, windows, doors, and outside walls. Put as many walls as possible between you and the outside. Get under a sturdy table and use your arms to protect your head and neck. Do not open windows.
A vehicle, trailer, or mobile home Get out immediately and go to the lowest floor of a sturdy, nearby building or a storm shelter. Mobile homes, even if tied down, offer little protection from tornadoes.
The outside with no shelter Lie flat in a nearby ditch or depression and cover your head with your hands. Be aware of the potential for flooding.

Do not get under an overpass or bridge. You are safer in a low, flat location.

Never try to outrun a tornado in urban or congested areas in a car or truck. Instead, leave the vehicle immediately for safe shelter.

Watch out for flying debris. Flying debris from tornadoes causes most fatalities and injuries.

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