thunderstorms...

tornadoes...

lightning...

thunderstorms...

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ightning...

ornadoes...

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A PREPAREDNESS GUIDE

Including Tornado Safety Information for Schools

U.S. DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

National Weather Service

NAT OI NAL OCEANIC AND ATMOSPHERIC ADMINISTRAT OI N

U.S. DEPARTMENT OF COMMERCE

Dave Williams, Wichita Eagle

Nature s

Most Violent

Storms

Nature s’

Most Violent

Storms

’

© Warren Faidley, Weatherstock
FAMILY DISASTER PLAN

NOAA/PA 99050

ARC 1122

LOCAL SPONSORSHIP:

Families should be prepared for all hazards that could affect their area. NOAA’s National Weather Service,

the Federal Emergency Management Agency, and the American Red Cross urge every family to develop a

family disaster plan.

Where will your family be when disaster strikes? They could be anywhere—at work, at school, or in the car.

How will you find each other? Will you know if your children are safe? Disaster may force you to evacuate

your neighborhood or confine you to your home. What would you do if basic services—water, gas,

electricity, or telephones—were cut off?

Follow these basic steps to develop a family disaster plan...

Gather information about hazards.

Meet with your family to create a plan.

Implement your plan.

Contact your local National Weather Service office, emergency

management office, and American Red Cross chapter. Find out what type of disasters could occur and

how you should respond. Learn your community’s warning signals and evacuation plans.

Discuss the information you have gathered. Pick two places to

meet: a spot outside your home for an emergency, such as fire, and a place away from your neighborhood

in case you can’t return home. Choose an out-of-state friend as your “family check-in contact” for

everyone to call if the family gets separated. Discuss what you would do if advised to evacuate.

(1) Post emergency telephone numbers by phones; (2) Install safety features in your

house, such as smoke detectors and fire extinguishers; (3) Inspect your home for potential hazards (such

as items that can move, fall, break, or catch fire) and correct them; (4) Have your family learn basic safety

measures, such as CPR and first aid; how to use a fire extinguisher; and how and when to turn off water,

gas, and electricity in your home; (5) Teach children how and when to call 911 or your local Emergency

Medical Services number; (6) Keep enough supplies in your home to meet your needs for at least three

days. Assemble a disaster supplies kit with items you may need in case of an evacuation. Store these

supplies in sturdy, easy-to-carry containers, such as backpacks or duffle bags. Keep important family

documents in a waterproof container. Keep a smaller disaster supplies kit in the trunk of your car.

Practice and maintain your plan. Ask questions to make sure your family remembers meeting places,

phone numbers, and safety rules. Conduct drills. Test your smoke detectors monthly and change the

batteries two times each year. Test and recharge your fire extinguisher(s) according to manufacturer’s

instructions. Replace stored water and food every 6 months. Contact your local National Weather

Service office, American Red Cross chapter, or local office of emergency management for a copy of

“Your Family Disaster Plan” (L-191/ARC4466).

I.

II.

III.

IV.

A DISASTER SUPPLIES KIT SHOULD INCLUDE:

A 3-day supply of water (one gallon per person per day) and food that won’t spoil one change of

clothing and footwear per person one blanket or sleeping bag per person a first aid kit, including

prescription medicines emergency tools, including a battery-powered NOAA Weather Radio and a

portable radio, flashlight, and plenty of extra batteries an extra set of car keys and a credit card or

cash special items for infant, elderly, or disabled family members.

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Introduction... Introduction...

Why Talk About Thunderstorms? They Produce...

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Lightning...

Strong Winds...

Flash Flooding...

Hail...

Tornadoes...

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each year

Causes an average of 80 fatalities and 300 injuries each year.

Occurs with all thunderstorms.

Is the #1 cause of deaths associated with thunderstorms...more than

140 fatalities each year.

Cause an average of 70 fatalities and 1,500 injuries .

Produce wind speeds in excess of 250 mph.

Can be one mile wide and stay on the ground over 50 miles.

Can exceed 100 mph.

Can cause damage equal to a tornado.

Can be extremely dangerous to aviation.

Causes more than $1 billion in crop and property damage each year.

For More Information

Contact your local National Weather Service office, American Red Cross chapter, or the Federal Emergency

Management Agency for a variety of weather-related brochures. Specific information on flash flooding

can be found in the “Flash Floods and Floods...The Awesome Power” brochure (NOAA PA 92050).

Brochures can be viewed and downloaded from the Internet at

Preparedness information can be obtained from the at

www.nws.noaa.gov/om/brochures.shtml

www.fema.gov/library/prepandprev.shtm 

Federal Emergency Management Agency

or the Red Cross at www.redcross.org/services/disaster/keepsafe/

This preparedness guide explains thunderstorms

and related hazards and suggests life-saving

actions can take. With this information, YOU

YOU

YOU!

can recognize severe weather, develop a

plan, and be ready to act when threatening weather

approaches. Remember...your safety is up to
What Are Thunderstorms? What Causes Them?

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The National Weather Service considers a thunderstorm severe if it produces hail at least 3/4-inch in

diameter, winds of 58 mph or er, or a tornado.

Every Thunderstorm Needs:

to form clouds and rain.

warm air that can rise rapidly.

cold or warm fronts, sea breezes, mountains, or the sun’s heat

are capable of lifting air to help form thunderstorms.

Moisture

Unstable air

Lift

Developing Stage

Usually little if any rain

during this stage.

Towering cumulus cloud

indicates rising air.

Lasts about 10 minutes.

Occasional lightning.

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Mature Stage

Most likely time for hail, heavy

rain, frequent lightning, strong

winds, and tornadoes.

Storm occasionally has a black

or dark green appearance.

Lasts an average of 10 to 20

minutes but may last much

longer in some storms.

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Dissipating Stage

Rainfall decreases in

intensity.

Can still produce a burst of

strong winds.

Lightning remains a danger.

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Thunderstorms... Thunderstorms...

Life Cycle of a Thunderstorm

NOAA

1,800 thunderstorms occur at any moment around the world. That's 16 million a year!

Thunderstorms affect relatively small areas when

compared with hurricanes and winter storms.

The typical thunderstorm is 15 miles in diameter and

Despite

their small size, ALL thunderstorms are dangerous!

lasts an average of 30 minutes. Of the estimated

100,000 thunderstorms that occur each year in the

United States, about 10 percent are classified

as severe.
Although tornadoes occur in many parts of the world, they are found most frequently in the United States.

In an average year, 1,200 tornadoes cause 70 fatalities and 1,500 injuries nationwide. You can find statistical

information on tornadoes at . www.spc.noaa.gov

Tornado Facts

When and Where Tornadoes Occur

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A tornado is a violently rotating column of air

extending from a thunderstorm to the ground.

Tornadoes may appear nearly transparent until

dust and debris are picked up or a cloud forms

within the funnel. The average tornado moves

from southwest to northeast, but tornadoes

have been known to move in any direction.

The average forward speed is 30 mph but may

vary from nearly stationary to 70 mph.

The strongest tornadoes have rotating winds of

more than 250 mph.

Tornadoes can accompany tropical storms and

hurricanes as they move onto land.

Waterspouts are tornadoes which form over

warm water. They can move onshore and

cause damage to coastal areas.

Tornadoes can occur at any time of the year.

Tornadoes have occurred in every state, but

they are most frequent east of the Rocky

Mountains during the spring and summer

months.

In the southern states, peak tornado occurrence

is March through May, while peak months in

the northern states are during the late spring

and summer.

Tornadoes are most likely to occur between

3 and 9 p.m. but can happen at any time.

Tornadoes... Tornadoes...

© Greg Stumpf
Before thunderstorms develop, a

change in wind direction and an

increase in wind speed with

increasing height creates an

invisible, horizontal spinning

effect in the lower atmosphere.

Rising air within the thunderstorm

updraft tilts the rotating air from

horizontal to vertical.

An area of rotation, 2-6 miles

wide, now extends through much

of the storm. Most tornadoes form

within this area of strong rotation.

How Tornadoes Form

Tornadoes Take Many Shapes and Sizes

Weak Tornadoes

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88% of all tornadoes

Less than 5% of tornado deaths

Lifetime 1 – 10+ minutes

Winds less than 110 mph

Strong Tornadoes

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11% of all tornadoes

Nearly 30% of all tornado deaths

May last 20 minutes or longer

Winds 110-205 mph

Violent Tornadoes

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Less than 1% of all tornadoes

70% of all tornado deaths

Lifetime can exceed 1 hour

Winds greater than 205 mph

Peter Willing

NOAA

Charles Doswell III Mary Hurley
Tornado Myths and Truths

MYTH

TRUTH

MYTH

TRUTH

MYTH

TRUTH

MYTH

TRUTH

MYTH

TRUTH

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Areas near lakes, rivers, and mountains are safe from tornadoes.

No place is safe from tornadoes. A tornado near Yellowstone National Park left a path of

destruction up and down a 10,000 foot mountain.

The low pressure with a tornado causes buildings to “explode” as the tornado passes overhead.

Violent winds and debris slamming into buildings cause most structural damage.

Windows should be opened before a tornado approaches to equalize pressure and

minimize damage.

Leave the windows alone. The most important action is to immediately go to a safe shelter.

If you are driving and a tornado is sighted, you should turn and drive at right angles to the storm.

The best thing to do is to seek the best available shelter. Many people are injured or killed when

remaining in their vehicles.

People caught in the open should seek shelter under highway overpasses.

Take shelter in a sturdy reinforced building if at all possible. Overpasses, ditches, and culverts

may provide limited protection from a tornado, but your risk will be greatly reduced by moving

inside a strong building.

Frequently asked questions about tornadoes can be found on the Internet at

www.spc.noaa.gov/faq/tornado/index.html.

The National Weather Service has strategically

located Doppler radars across the country that can

detect air movement toward or away from a radar.

Early detection of increasing rotation aloft within a

thunderstorm can allow life-saving warnings to be

issued before the tornado forms. In the figure below

left, Weather Service Doppler radar detected strong

rotation within the storm where red colors (winds

moving away from the radar) and green (winds

blowing toward the radar) are close together. The

photograph at below right shows a violent tornado in

northern Oklahoma at the same time the radar image

was taken.

Weather Radar Watches the Sky

Doppler Radial Velocity Jim Ladue
Lightning Facts

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Lightning causes an average of 80 fatalities and

300 injuries each year.

Lightning occurs in all thunderstorms; each year

lightning strikes the Earth 20 million times.

The energy from one lightning flash could light a

100-watt light bulb for more than 3 months.

Most lightning fatalities and injuries occur when

people are caught outdoors in the summer months

during the afternoon and evening.

Lightning can occur from cloud-to-cloud, within a

cloud, cloud-to-ground, or cloud-to-air.

Many fires in the western United States and Alaska

are started by lightning.

■ The air near a lightning strike is heated to 50,000°F

The rapid heating

and cooling of the air near the lightning channel

causes a shock wave that results in .

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hotter than the surface of the sun!

thunder

How Lightning Forms

Lightning results from the buildup and discharge of electrical energy

between positively and negatively charged areas. Rising and descending

air within a thunderstorm separates these positive and negative charges.

Water and ice particles also affect charge distribution.

A cloud-to-ground lightning strike begins as an invisible channel of

electrically charged air moving from the cloud toward the ground.

When one channel nears an object on the ground, a powerful surge of

electricity from the ground moves upward to the clouds and produces

the visible lightning strike.

Lightning... Lightning...

NOAA

Johnny Autery

How far away is the Thunderstorm?

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Count the number of seconds between a flash

of lightning and the next clap of thunder.

Divide this number by 5 to determine the

distance to the lightning in miles.
In recent years, people have been killed by lightning while:

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boating standing under a tree riding a horse

swimming riding on a lawnmower playing soccer

golfing talking on the telephone fishing in a boat

bike riding loading a truck mountain climbing

Lightning Myths and Truths

MYTH

TRUTH

MYTH

TRUTH

MYTH

TRUTH

MYTH

TRUTH

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If it is not raining, then there is no danger from lightning.

Lightning often strikes outside of heavy rain and may occur as far as 10 miles away from

any rainfall. This is especially true in the western United States where thunderstorms sometimes

produce very little rain.

The rubber soles of shoes or rubber tires on a car will protect you from being struck by lightning.

Rubber-soled shoes and rubber tires provide protection from lightning. The steel frame of a

hard-topped vehicle provides increased protection if you are not touching metal. Although you

may be injured if lightning strikes your car, you are much safer inside a vehicle than outside.

People struck by lightning carry an electrical charge and should not be touched.

Lightning-strike victims carry no electrical charge and should be attended to immediately.

Contact your local American Red Cross chapter for information on CPR and first aid classes.

“Heat lightning” occurs after very hot summer days and poses no threat.

“Heat lightning” is a term used to describe lightning from a thunderstorm too far away for

thunder to be heard.

NO

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.

Robert Prentice
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Straight-line winds are responsible for most

thunderstorm wind damage.

Winds can exceed 100 mph!

One type of straight-line wind, the downburst, is a

small area of rapidly descending air beneath a

thunderstorm (see center of ).

A downburst can cause damage equivalent to a strong

tornado and can be extremely dangerous to aviation.

A “dry microburst” is a downburst that occurs with

little or no rain. These destructive winds are most

common in the western United States.

photograph below

Straight-line Wind Straight-line Winds...

Bill Bunting Bill Bunting

Brandt Graham

Flash Floods / Floods... Flash Floods / Floods...

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Flash floods and floods are the #1 cause of deaths

associated with thunderstorms...more than 140

fatalities each year.

Most flash flood fatalities occur at night and most

victims are people who become trapped in

automobiles.

Six inches of fast-moving water can knock you off

your feet; a depth of two feet will cause most

vehicles to float.

For more information, refer to the Flash Floods and

Floods...The Awesome Power brochure on the Internet at

www.nws.noaa.gov/om/brochures.shtml . © Warren Faidley, Weatherstock
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Strong rising currents of air within a storm, called

updrafts, carry water droplets to a height where

freezing occurs.

Ice particles grow in size, becoming too heavy to

be supported by the updraft, and fall to the ground.

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Causes more than $1 billion in damage to

property and crops each year.

Large stones fall at speeds faster than 100 mph.

From Lightning

From Flash Flooding

From Tornadoes

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People who are outdoors,

especially under or near tall

trees; in or on water; or on or

near hilltops.

People who walk or drive

through flood waters.

People who are in mobile

homes and automobiles.

Large Hail... Large Hail...

National Center for Atmospheric Research

National Severe Storms Laboratory, NOAA

National Climatic Data Center, NOAA

Who’s Most At Risk from Thunderstorms?
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National Weather Service watches and warnings

are also available on the Internet. Select your

local National Weather Service office at

or go

to the National Weather Service Home Page at

.

Listen to radio and television for weather

information.

Check the weather forecast before leaving for

extended periods outdoors. Watch for signs of

approaching storms.

If severe weather threatens, check on people who

are elderly, very young, or physically or

mentally disabled.

www.nws.noaa.gov/organization.html

www.nws.noaa.gov

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Develop a plan for you and your family at home,

work, school, and when outdoors. The American

Red Cross offers planning tips on their Internet site:

.

Identify a safe place to take shelter. Information

on how to build a Safe Room (shown in the photos

below) in your home or school is available from

the Federal Emergency Management Agency at

.

Have frequent drills.

Know the county/parish in which you live or visit.

The National Weather Service issues severe

weather warnings on a county or parish basis.

Keep a highway map nearby to follow storm

movement from weather bulletins.

Have a NOAA Weather Radio with a warning

alarm tone and battery back-up to receive warnings.

www.redcross.org/services/disaster/keepsafe/

www.fema.gov/hazard/tornado/to_saferoom.shtm

What Can Do Before Severe Weather Strikes YOU

Be Prepared... Be Prepared...

It's Up to YOU!

Each year, many people are killed or seriously injured

by tornadoes and severe thunderstorms despite

advance warning. Some did not hear the warning,

while others heard the warning but did not believe it

would happen to them. The following preparedness

information, combined with timely severe weather

watches and warnings, could save your life. Once

you receive a warning or observe threatening skies,

must make the decision to seek shelter before

the storm arrives. It could be the most important

decision you will ever make.

YOU

NOAA

FEMA
What Can Do

When Threatening Weather Approaches

YOU

Lightning Safety Rules

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Postpone outdoor activities if thunderstorms are

imminent. This is your best way to avoid being

caught in a dangerous situation.

Move to a sturdy building or car. Do not take

shelter in small sheds, under isolated trees, or in

convertible automobiles. Stay away from tall

objects such as towers, fences, telephone poles,

and power lines.

If lightning is occurring and a sturdy shelter is not

available, get inside a hard top automobile and

keep the windows up. Avoid touching any metal.

Utility lines and metal pipes can conduct

electricity. Unplug appliances not necessary for

obtaining weather information. Avoid using the

telephone or any electrical appliances. Use

phones ONLY in an emergency.

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Do not take a bath or shower during a thunderstorm.

Turn off air conditioners. Power surges from

lightning can cause serious damage.

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Find a low spot away from trees, fences, and poles.

Make sure the place you pick 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 over your ears and your

head between your knees. Make yourself the

smallest target possible and minimize your

contact with the ground. DO NOT lie down.

If you are boating or swimming, get to land and

find shelter immediately!

If Caught Outdoors and No Shelter Is Nearby

Todd Heitkamp

NOAA

Remember, if you can hear thunder – you are close enough to be struck by lightning!
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In a home or building, move to a pre-designated shelter, such

as a basement.

If an underground shelter is not available, move to a small

interior room or hallway on the lowest floor and get under a

sturdy piece of furniture. Put as many walls as possible

between you and the outside.

Stay away from windows.

Get out of automobiles.

Do not try to outrun a tornado in your car; instead, leave it

immediately for safe shelter.

If caught outside or in a vehicle, lie flat in a nearby ditch or

depression and cover your head with your hands.

Be aware of flying debris. Flying debris from tornadoes

causes most fatalities and injuries.

Mobile homes, even if tied down, offer little protection from

tornadoes. You should leave a mobile home and go to the

lowest floor of a sturdy nearby building or a storm shelter.

Tornado Safety Rules

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Avoid walking, swimming, or driving in

flood waters.

Stay away from high water, storm drains,

ditches, ravines, or culverts. If it is moving

swiftly, even water six inches deep can

knock you off your feet.

If you come upon flood waters, stop, turn

around, and go another way. Climb to

higher ground.

Do not let children play near storm drains.

Flash Flood Safety Rules

Occasionally, tornadoes develop so rapidly that advance warning is not possible.

Remain alert for signs of an approaching tornado such as a dark, often greenish sky,

large hail, or a loud roar similar to a freight train.

Bill Bunting

NOAA
Every School Should Have a Plan

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Develop an action plan with frequent drills.

Each school should be inspected and shelter areas

designated by a registered engineer or architect.

Basements offer the best protection. Schools

without basements should use interior rooms and

hallways on the lowest floor and away from

windows.

Ensure students know the protection position

(shown at right).

Each school should have a NOAA Weather Radio

with battery back-up.

If the school’s alarm system relies on electricity,

have an alternative method to notify teachers and

students in case of power failure.

Make special provisions for disabled students and

those in portable classrooms.

Delay lunches or assemblies in large rooms if

severe weather is anticipated. Gymnasiums,

cafeterias, and auditoriums offer no protection

from tornado-strength winds.

Keep children at school beyond regular hours until

threatening weather passes. Children are safer at

school than in a bus or car.

Tornado Safety in Schools... Tornado Safety in Schools...

Hospitals, nursing homes, and other institutions should develop similar plans.

The National Weather Service, the Federal

Emergency Management Agency, and the American

Red Cross educate community officials and the

public about the dangers posed by tornadoes and

severe thunderstorms. can prepare for this

possibility by learning the safest places to seek

YOU

shelter when at home, work, school, or outdoors.

Learn basic weather terms and danger signs. Your

chances of staying safe during severe weather are

greater if you have a plan for you and your family,

and practice the plan frequently.

NOAA
Stay Informed...

Use NOAA

Weather Radio

When conditions are favorable for severe weather to

develop, a severe thunderstorm or tornado WATCH is issued.

Weather Service personnel use information from weather

radar, spotters, and other sources to issue severe

thunderstorm and tornado WARNINGS for areas where

severe weather is imminent. Severe thunderstorm and

tornado warnings are passed to local radio and television

stations and are broadcast over local NOAA Weather Radio

stations serving the warned areas. These warnings are also

relayed to local emergency management and public safety

officials who can activate local warning systems to alert

communities. If a tornado warning is issued for your area or

the sky becomes threatening, move to your pre-designated

place of safety.

Check with your local National Weather Service office or

visit the Internet site to determine

if your county is covered by NOAA Weather Radio. National

Weather Service watches and warnings are also available on

the Internet by selecting your local National Weather Service

office at or by

going to the National Weather Service Home Page at

.

www.nws.noaa.gov/nwr/

www.nws.noaa.gov/organization.html

www.nws.noaa.gov

What to Listen For...

Tornado Watch:

Severe Thunderstorm Watch:

Tornado Warning:

Severe Thunderstorm Warning:

Tornadoes are possible

in your area. Remain alert for

approaching storms. Know what

counties or parishes are in the watch area

by listening to NOAA Weather Radio or

your local radio/television outlets.

Tells you

when and where severe thunderstorms

are likely to occur. Watch the sky and

stay tuned to know when warnings

are issued.

A tornado has been

sighted or indicated by weather radar.

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.

Stay Informed...

Use NOAA

Weather Radio

NOAA

The National Weather Service continuously broadcasts warnings and forecasts that can be received by NOAA

Weather Radios, which are sold in many stores. The average range is 40 miles, depending on topography.

Purchase a radio that has a battery back-up and a Specific Area Message Encoder feature, which automatically

alerts you when a watch or warning is issued for your county or parish.

NOAA Weather Radio is the best means to receive

warnings from the National Weather Service