Some thunderstorms can be seen approaching, while others hit without warning. It is important to learn and recognize the danger signs and to plan ahead.
WHAT IS A THUNDERSTORM?
A thunderstorm is a storm containing lightning caused by un stable atmospheric conditions. When cold upper air sinks and warm, moist air rises, storm clouds or "thunderheads" develop. Thunderstorms may occur singly, in clusters, or in lines. Thus, it is possible for several thunderstorms to affect one location in the course of a few hours. Some of the most severe weather occurs when a single thunderstorm affects one location for an extended period of time.
Severe thunderstorms can bring heavy rains (which can cause flash flooding), strong winds, hail, lightning, and tornadoes. To protect yourself in a severe thunderstorm, get inside a sturdy building and stay tuned to a battery-operated radio for weather information.
WHAT IS LIGHTNING?
Lightning is an electrical discharge that results from the buildup of static electricity within clouds, or between clouds and the ground. It always accompanies a thunderstorm. When the buildup is strong enough to overcome the insulating effect of the air, lightning appears as a "bolt". This flash of light can remain within the clouds, occur between clouds, or strike toward the ground several miles from the parent cloud.
Lightning is a major threat during a thunderstorm. In the United States, between 75 and 100 Americans are hit and killed each year by lightning. If you are caught outdoors, avoid natural lightning rods such as tall, isolated trees in an open area and metal objects such as wire fences, golf clubs, and metal tools.
It is a myth that lightning never strikes twice in the same place. In fact, lightning has favorite sites that it will strike several times in the course of one storm. While thunderstorms and lightning can be found throughout the United States, they are most likely to occur in the central and southern states. The state with the highest number of thunderstorms is Florida.
B E F O R E
Learn the thunderstorm danger signs- Dark, towering, or threatening clouds; Distant lightning and thunder.
Have emergency supplies on hand. Check for hazards in the yard. Dead or rotting trees and branches can fall during a severe thunderstorm and cause injury or damage.
Secure outdoor objects such as lawn furniture that could blow away or cause damage or injury. Take light objects inside. Shutter windows securely and brace outside doors. Turn on the battery operated radio or television to get the latest storm information.
Know the difference between a "severe thunderstorm watch" and a "severe thunderstorms warning".
A Severe Thunderstorm Watch is issued by the National Weather Service when the weather conditions are such that a severe thunderstorm (damaging winds 58 miles per hour or more, or hail three-fourths of an inch in diameter or greater) is likely to develop. This is the time to locate a safe place in the home and tell family members to watch the sky and listen to the radio or television for more information.
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 the "all clear" from authorities.
Learn how to respond to a tornado and flash flood. Tornadoes are spawned by thunderstorms and flash flooding can occur with thunderstorms. When a "severe thunderstorm warning" is issued, review what actions to take under a "tornado warning" or a "flash flood warning".
D U R I N G
If indoors:
Do not handle any electrical equipment or telephones, because lightning could follow the wire. Television sets are particularly dangerous at this time. Avoid bathtubs, water faucets, and sinks because metal pipes can transmit electricity.
If outdoors:
Attempt to get into a building or car. If no structure is available, get to an open space, preferably low to the ground, as quickly as possible. (If in the woods, find an area protected by a low clump of trees - never stand underneath a single large tree in the open.)
Avoid tall structures such as towers, tall trees, fences, telephone lines, or power lines. Stay away from natural lightning rods such as golf clubs, tractors, fishing rods, bicycles, or camping equipment.
Kneel or crouch with hands on knees. Stay away from rivers, lakes, or other bodies of water.
If in a car:
Pull safely onto the shoulder of the road away from any trees that could fall on the vehicle. Stay in the car and turn on the emergency flashers until the heavy rains subside.
Estimating the Distance from a Thunderstorm
Because light travels so much faster than sound, lightning flashes can be seen long before the resulting thunder is heard. Estimate the number of miles you are from a thunderstorm by counting the number of seconds between a flash of lightning and the next clap of thunder. Divide this number by five.
Hail
Hail is produced by many strong thunderstorms. Hail can be smaller than a pea or as large as a baseball, and can be very destructive to plants and crops. In a hailstorm, take cover immediately. Pets and livestock are particularly vulnerable to hail, so bring animals into a shelter.
A F T E R
Check for injuries. A person who has been struck by lightning does not carry an electrical charge that can shock other people. If the victim is burned, provide first aid and call 911 immediately. Look for burns where lightning entered and exited the body. If the strike caused the victim's heart and breathing to stop, give cardiopulmonary resuscitation (CPR) until medical professionals arrive and take over.
Report downed utility wires. Drive only if necessary. Debris, downed wires, and washed-out roads may make driving dangerous.
