Thunderstorms and Lightning

Despite their small size, all thunderstorms are dangerous. Every thunderstorm produces lightning, which kills more people each year than tornadoes. Heavy rain from thunderstorms can lead to flash flooding. Strong winds, hail, and tornadoes are also dangers associated with some thunderstorms.

Thunderstorms affect relatively small areas when compared with hurricanes and winter storms. The typical thunderstorm is 15 miles in diameter and lasts an average of 20 to 30 minutes. Nearly 1,800 thunderstorms are happenings at any moment in the world, or 16 million thunderstorms occur in one year. It is estimated that 100,000 thunderstorms occur in the United States each year.

The National Weather Service considers a thunderstorm severe if it produces hail at least three-quarters of an inch in diameter, has winds of 58 miles per hour or higher or produces a tornado. When a severe thunderstorm warning is issued, review what actions to take under a tornado or a flash flood warning.

Thunderstorms may occur singly, in clusters, or in lines. Some of the most severe weather occurs when a single thunderstorm affects one location for an extended period of time. Lightning is a major threat during a thunderstorm. Lightning is very unpredictable, which increases the risk to individuals and property. Approximately 93 persons are killed by lightning each year in the United States and 300 persons are injured. Persons struck by lightning often report a variety of long-term debilitating symptoms, including memory loss, attention deficits, sleep disorders numbness, dizziness, stiffness in joints, irritability, fatigue, weakness, muscle spasms, depression, and an inability to sit for long.

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 toward you.

You are in danger from lightning if you can hear thunder. Because light travels so much faster than sound, lightning flashes can sometimes be seen long before the resulting thunder is heard. When the lightning and thunder occur very close to one another, the lightning is striking nearby. To estimate the number of miles you are from a thunderstorm, count the number of seconds between a flash of lightning and the next clap of thunder. Divide this number by five.

Many strong thunderstorms produce hail. Large hail, or flying glass from hail damage can injure people and animals. Hail can be smaller than a pea or as large as a softball, and can be very destructive to automobiles, glass surfaces, roofs, plants, and crops. In a hailstorm, take cover immediately. Pets and livestock are particularly vulnerable to hail, so bring animals into shelter before storms begin.

Downbursts and straight-line winds associated with thunderstorms can produce winds up to 100 to 150 miles per hour, enough to flip cars, vans and semis. The resulting damage can equal the damage of most tornadoes. If a severe thunderstorm warning is issued, take shelter the same way you would if a tornado was approaching your area. Leave structures that are susceptible to being blown over in high winds, such as a mobile home.

Develop a Family Thunderstorm Plan

ü Learn about your area's thunderstorm risk. Severe thunderstorms can occur year-round and at any hour. Contact your local emergency management office, local National Weather Service office, of American Red Cross chapter for more information.

ü Pick a "safe place" in your home where family members can gather during a thunderstorm. This should be a place where there are no windows, skylights, or glass doors, which could be broken by strong winds or hail, causing damage or injury. Severe thunderstorms do, at times, produce tornadoes.

ü In preparation for possible tornado warnings, consider making your severe thunderstorm "safe place" on the lowest floor of the building.

ü Teach family members to squat low to the ground if they are caught outside in a thunderstorm. Squatting makes you less of a target for lightning and helps to avoid contact with the ground. Lightning current often enters a victim through the ground rather than by a direct overhead strike. Assume a crouched position on the ground with only the balls of the feet touching the ground, place your hands on your knees, and lower your head. Minimize your body's surface area, and minimize contact with the ground.

What to do during a severe thunderstorm watch

ü Listen to a NOAA Weather Radio, or local radio or television stations for updated information.

ü Avoid natural lightning rods as golf clubs, fishing poles, tractors, bicycles, and camping equipment. Lightning is attracted to metal and poles and rods.

ü Be prepared to seek shelter if a severe thunderstorm approaches. A sturdy building is the safest place to be during a sever thunderstorm. Avoid unprotected gazebos, rain or picnic shelters, golf cars, baseball dugouts, and bleachers. While many people take shelter from rain in these locations, they are often isolated structures in otherwise open areas, and therefore, a target for lightning. In addition, gazebos and picnic shelters are often poorly anchored and subject to being uprooted and blown around in strong thunderstorm winds. They also offer little protection from large hail.

What to do during a thunderstorm warning

ü Listen to a NOAA Weather Radio or battery-powered radio or television for updated emergency information. If the power goes out, you still have access to important information

ü Draw blinds and shades over windows. If windows break due to objects blown by the wind of large hail, the shades will help prevent glass from shattering into your house.

ü Unplug appliances. Avoid using the telephone or any electrical appliances. If lightning strikes, telephone lines and metal pipes can conduct electricity. Leaving electric lights on does not increase the chances of your home being struck by lightning.

ü Avoid taking a bath or shower, or running water for any other purpose. Meal pipes and plumbing can conduct electricity if struck by lightning.

ü Turn off the air conditioner. Power surges from lightning can overload the compressor, resulting in a costly repair job.

If you are outside and a severe thunderstorm is approaching

ü If you are boating or swimming, get to land, get off the beach, and find shelter immediately. Stay away from rivers lakes, and other bodies of water. Water is an excellent conductor of electricity. When lightning strikes nearby, the electrical charge can travel through the water and kill persons in the water.

ü Take shelter in a substantial, permanent, enclosed structures, such as reinforced buildings.

ü If there are no reinforces buildings in sight, take shelter in a car. Keep car windows closed and avoid convertibles. 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.

ü If no structure is available, go to a low-lying, open space away from trees, poles, or metal objects. Make sure the place you pick is not subject to flooding. Have as little contact with the ground as possible. Squat low to the ground. Place your hands on your knees with your head between them. Make yourself the smallest target possible. Do not lie flat on the ground - this will make you a larger target.

What to do while driving during a thunderstorm and heavy rain

ü Pull safely onto the shoulder of the road and stop, making sure you are away from any trees or other tall objects that could fall on the vehicle. Stay in the car and turn on the emergency flashers until the heavy rains subside.

ü Avoid contact with metal or conducting surfaces outside or inside the vehicle. Lightning that strikes nearby can travel through wet ground to your car. The steel frame of a hard-topped vehicle provides increased protection from lightning.

ü Avoid flooded roadways. Most flood fatalities are caused by people attempting to drive through water, or people playing in high water. The depth of water is not always obvious. The roadbed may be washed out under the water, and you could be stranded or trapped. Rapidly rising water may stall the engine, engulf the vehicle and its occupants, and sweep them away. Look out for flooding at highway dips, bridges, and low areas. Two feet of water will carry away most automobiles.

What to do if someone is struck by lightning

ü Call for help. Get someone to dial 911; medical attention is needed as quickly as possible.

ü Give first aid. If breathing has stopped, begin rescue breathing. If the heart has stopped beating, a trained person should give CPR. If the person has a pulse and is breathing, look and care for other possible injuries.

ü Check for burns in two places. The injured person has received an electrical shock and may be burned, both where they were struck and where electricity left their body. Being struck by lightning can also cause nervous system damage, broken bones, and loss of hearing or eyesight. People struck by lightning carry no electrical charge that can shock other people, and they can be handles safely.