The Severe Weather Safety Guide

Brought to you by MESO

(Multi-community Environmental Storm Observatory)


Thunderstorms...and their offspring

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 30 minutes. Nearly 1,800 thunderstorms are occurring at any moment around the world. That's 16 million a year!

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 dan gers associated with some thunderstorms.

Of the estimated 100,000 thunderstorms that occur each year in the United States, only about 10 percent are classified as severe.

Your National Weather Service considers a thunderstorm severe if it produces hail at least 3/4-inch in diameter, winds 58 mph or higher, or tornadoes.

Take the time NOW to understand these dangers and learn basic safety rules!

Flash Floods/Floods

•The number ONE thunderstorm killer...nearly 140 fatalities each year.

•Most flash flood deaths occur at night and when people become trapped in automobiles.


•Occurs with ALL thunderstorms.

•Averages 93 deaths and 300 injuries each year.

•Causes several hundred million dollars in damage to property and forests annually.

Straight-line Winds

•Responsible for most thunderstorm wind damage.

•Winds can exceed 100 mph!

•One type of straight-line wind, the downburst, can cause damage equivalent to a strong tornado and can be extremely dangerous to aviation.

•During the summer in the western states, thunderstorms often produce little rain but very strong wind gusts and dust storms.

Large Hail

•Causes nearly $1 billion in damage to property and crops annually.

•Costliest United States hailstorm: Denver, Colorado, July 11, 1990. Total damage was $625 million.

•The high plains of northern Colorado and southern Wyoming are the most frequent victims of hail storms, but any state that gets thunderstorms can get large hail.


•Nature's most violent storms.

•Winds can exceed 200 mph.

•Result in an average of 80 deaths and 1,500 injuries each year.

•Most fatalities occur when people do not leave mobile homes and automobiles.


Who's Most At Risk From Thunderstorms?

- From Lightning:

People who are: outdoors, especially under or near tall trees; in or on water; or on or near hilltops.

- From Flooding:

People who are in automobiles when flash flooding occurs near them

- From Tornadoes

People who are in mobile homes and automobiles.

Environmental clues

When skies darken or thunderstorms are forecast, look AND listen for

•Increasing wind.

•Flashes of lightning.

•Sound of thunder.

•Static on your AM radio.

To estimate the distance in miles between you and the lightning flash, count the seconds between the lightning and the thunder and divide by five.

Thunderstorms and lightning safety

What YOU Can Do!

Before the Storm...

•Know the county or parish in which you live and the names of nearby major cities. Severe weather warnings are issued on a county or parish basis.

•Check the weather forecast before leaving for extended periods outdoors.

•Watch for signs of approaching storms.

•If a storm is approaching, keep a NOAA Weather Radio or AM/FM radio with you.

•Postpone outdoor activities if thunderstorms are imminent. This is your best way to avoid being caught in a dangerous situation.

•Check on those who have trouble taking shelter if severe weather threatens.

When Thunderstorms Approach...

•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.

•If lightning is occurring and a sturdy shelter is not available, get inside a hard top automobile and keep windows up.

•Get out of boats and away from water.

•Telephone 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.

•Do not take a bath or shower.

•Turn off air conditioners. Power surges from lightning can overload the compressors.

•Get to higher ground if flash flooding or flooding is possible. Once flooding begins, abandon cars and climb to higher ground. Do not attempt to drive to safety. 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 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 on your knees with your head between them. Make yourself the smallest target possible, and minimize your contact with the groun d.

•If you are boating or swimming, get to land and find shelter immediately



by listening to NOAA Weather Radio, commercial radio, and television for the latest severe thunderstorm WATCHES and WARNINGS. Thunderstorms are rapidly-changing and are rarely the same size, intensity, or in the same place than they were five m inutes ago. Frequent updates are critical. Television/radio warnings or tornado sirens may come too late or not at all. Your eyes and ears are the best detection system. Stay alert!


The National Weather Service continuously broadcasts updated weather 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. Your National Weather Servic e recommends purchasing a radio that has both a battery backup and a tone-alert feature that automatically alerts you when a watch or warning is issued.

What to Listen For...

•SEVERE THUNDERSTORM WATCH: tells you when and where severe thunderstorms are more likely to occur. Watch the sky and stay tuned to know when warnings are issued. Watches are intended to heighten public awareness and should not be confused with warnings.

•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. Also listen for Tornado Watch or Warning and Flash Flood Watch or Warning.

•Also listen for Tornado Watch or Warning and flash Flood Watch or Warning.


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 yo ur 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...


I. Gather information about hazards. 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.

II. Meet with your family to create a plan. 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. Choos e 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.

III. Implement your plan.

(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 b ags. Keep important family documents in a waterproof container. Keep a smaller disaster supplies kit in the trunk of your car.


•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.

IV. 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).




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