THUNDERSTORMS AND LIGHTNING

Thunderstorms are our most common experience of severe weather. The typical thunderstorm is 15 miles in diameter and lasts an average of 30 minutes. Despite their small size, 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.

Of the estimated 100,000 thunderstorms that occur each year in the United States, only about 10% are classified as severe. The National Weather Service considers a thunderstorm severe if it produces hail at least 3/4 inch in diameter, wind 58 mph or higher or tornadoes. The five main offspring of thunderstorms are: lightning, floods, straight-line winds, large hail and tornadoes.

Lightning occurs with all thunderstorms. It averages 93 deaths and 300 injuries each year. It also causes several hundred million dollars in damage to property and forests annually.

Flash floods / floods are the number one thunderstorm killer... nearly 140 fatalities each year. Most flash flood deaths occur at night and when people become trapped in automobiles.

Straight line winds are responsible for most thunderstorm wind damage.

Winds can exceed 100mph! One type of straight line wind that can cause extreme damage is a downburst, a small area of rapidly descending air beneath a thunderstorm. Downbursts can reach speeds equal to that of a strong tornado and can be extremely dangerous to aviation.

Hail causes nearly $1 billion in damage to property and crops annually. Large hail stones can fall at speeds faster than 100mph. The costliest US hailstorm occurred in Denver, CO in July, 1990. Total damage was $625 million.

Lightning is perhaps the most spectacular phenomenon associated with thunderstorms. Most lightning deaths and injuries occur when people are caught outdoors, most often in the summer months and during the afternoon and early evening. In the past decade, over 15,000 lightning-induced fires nationwide have resulted in several hundred million dollars a year in damage and the loss of 2 million acres of forest. Your chances of being struck by lightning are estimated to be 1 in 600,000 but could be reduced by following safety rules.

What to listen for...

When conditions are favorable for severe weather to develop, a severe thunderstorm watch is issued.

When severe weather has been reported by spotters or indicated by radar, a severe thunderstorm warning is issued. Warnings indicate imminent danger to life and property to those in the path of the storm.

What you can do--Be safe!

Before the storm...

Check weather forecasts before leaving for extended periods outdoors.
Watch for signs of approaching storms.
Postpone outdoor activities if thunderstorms are imminent. This is your best way to avoid being caught in a dangerous situation.
When a thunderstorm approaches...
Remember: if you can hear thunder, you are close enough to the storm to be struck by lightning. Go to safe shelter immediately!
Move to a sturdy building or car. DO NOT take shelter in small sheds, under isolated trees, or in convertible automobiles.
Get out of boats and stay away from water.
Avoid using the telephone or any other electrical appliances. Use the phone only in an emergency.
Do not take a bath/shower.
Turn off air conditioners.
Get to higher ground if flooding is possible. Abandon cars and climb to higher ground. Note: most flash flood deaths occur in automobiles.
If caught outdoors and no shelter is nearby...
Find a low spot away from trees, fences and poles. Make sure the place is not subject to flooding.
If you are in the woods, take shelter under the shorter trees.
If you feel your skin tingle or your hair stand on end, squat low to the ground on the balls of your feet. Place your hands on your knees with your head between them. Make yourself the smallest target possible and minimize your contact with the ground.

A PREPAREDNESS GUIDE
By: Chris Floyd
Emergency Services Director
Capital Area Chapter
American Red Cross

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.

The following are 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.

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

Every thunderstorm produces lightning.
Never touch a person struck by lightning.
Dry, cold conditions favor development of a thunderstorm.
If you can count to 25 after seeing lightning and before hearing thunder, it is safe to stay outdoors.
It is safe to use a cordless telephone during a thunderstorm.
Rubber-soled shoes and rubber tires provide protection from lightning.