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* 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.
The
following are 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.
Know
the Terms
Familiarize yourself with these terms to help identify a thunderstorm hazard:
Severe Thunderstorm: WatchTells
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.
Take
Protective Measures
Before Thunderstorms and Lightning
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.
* Remember
the 30/30 lightning safety rule: Go indoors if, after seeing lightning, you cannot count to 30 before hearing thunder. Stay
indoors for 30 minutes after hearing the last clap of thunder.
Thunderstorms
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
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.
After
a Thunderstorm
Call 9-1-1 for medical assistance as soon as possible.
The following are things you should check
when you attempt to give aid to a victim of lightning:
* Breathing - if breathing has stopped, begin mouth-to-mouth
resuscitation.
* Heartbeat - if the heart has stopped, administer CPR.
* Pulse - if the victim has a pulse and is breathing,
look for other possible injuries. Check for burns where the lightning entered and left the body. Also be alert for nervous
system damage, broken bones, and loss of hearing and eyesight.
Knowledge Check
Decide whether the following statements
are true or false. When you have finished, verify your answers using the answer key.
True of False Statements
1.
Every thunderstorm produces lightning.
2. Never touch a person struck by lightning.
3. Dry, cold conditions favor development
of a thunderstorm.
4. If you can count to 25 after seeing lightning and before hearing thunder, it is safe to stay outdoors.
5.
It is safe to use a cordless telephone during a thunderstorm.
6. Rubber-soled shoes and rubber tires provide protection
from lightning.
Where does lightning usually strike?
Lightning strikes the ground somewhere in the U.S. nearly
every day of the year. Thunderstorms and lightning occur most commonly in moist warm climates. Data from the National Lightning
Detection Network shows that over the continental U.S. an average of 20,000,000 cloud-to-ground flashes occur every year.
Around the world, lightning strikes the ground about 100 times each second, or 8 million times a day. Ground-based systems
don't tell us anything about lightning over the oceans, although a few science satellites have lightning detectors on them
now. There are roughly 5 to 10 times as many cloud flashes as there are to cloud-to-ground flashes, so the total amount of
lightning is quite a bit higher.
These conditions most often occur in summer. In general, the US mainland has a decreasing
amount of lightning toward the northwest. Over the entire year, the highest frequency of cloud-to-ground lightning is in Florida
between Tampa and Orlando. This is due to the presence, on many days during the year, of a large moisture content in the atmosphere
at low levels (below 5,000 feet), as well as high surface temperatures that produce strong sea breezes along the Florida coasts.
The western mountains of the US also produce strong upward motions and contribute to frequent cloud-to-ground lightning. There
are also high frequencies along the Gulf of Mexico coast westward to Texas, the Atlantic coast in the southeast US, and inland
from the Gulf. Regions along the Pacific west coast have the least cloud-to-ground lightning. |
