Lightning Safety

Because of the capricious nature of thunderstorms, no one can guarantee an individual or group absolute protection from lightning.  However,  knowing and following proven lightning safety guidelines can greatly reduce the risk of injury or death.

Remember, YOU are ultimately responsible for your personal safety, and should take appropriate action when threatened by Florida's #1 weather related killer - LIGHTNING.

Safe Locations During a Lightning Storm:

No place is absolutely safe from lightning!  However, some places are much safer than others...

One of the safest locations you can be during a thunderstorm is a large enclosed structure.  A large enclosed structure is typically a building which is occupied by people on a permanent basis, with plumbing and electrical wiring.  These include shopping centers, schools, office buildings, or private residences.  If no buildings are available, then  enclosed metal vehicles such as automobiles, vans, and school buses are good alternatives. 

Once in a sturdy building, stay away from electrical appliances and plumbing fixtures.  Lightning can travel great distances through power lines, especially in rural areas.  Cordless and cell phones can be used, but DO NOT use a corded phone unless it is an emergency.  Computers are also dangerous, as they usually are connected to both phone and electrical cords.  If you are inside a vehicle, roll the windows up, and avoid contact with any conducting paths leading to the outside of the vehicle (e.g. radios, CB's, ignition, etc.). (Contrary to popular belief, the vehicle's rubber tires DO NOT "insulate" you from the lightning.  The vehicle's metal shell conducts the lightning around and away from you.)

Not all types of buildings or vehicles are safe during thunderstorms.  Buildings which are NOT SAFE (even if they are "grounded") include beach shacks, metal sheds, picnic shelters/pavilions, carports, and baseball dugouts.  In general, buildings with exposed openings such as those mentioned above are NOT SAFE.  Vehicles such as convertibles offer no safety from lightning, even if the top is "up".  Other vehicles which are NOT SAFE during lightning storms are those which have "open" cabs, such as golf carts, open cab tractors/construction equipment, etc.

Lightning Safety Action Plan:

An effective lightning safety plan begins LONG before a lightning threat is realized.  Every outdoor event coordinator should consider the probability of lightning, especially during the summer.  As such events often are planned many months in advance, it is important to include a lightning safety action plan during the event's planning stages.  Do not wait for storm clouds to develop before considering an action plan!

 The key to a lightning safety action plan is knowing the answer to the following two questions: 1) How far away am I (or the group I am responsible for) from a safe location? and 2) How long will it take me (or my group) to get to the safe location?  These questions need to be answered before thunderstorms threaten.  Knowing the answer to the above questions will greatly reduce your chances of being struck by lightning.

The 30/30 Rule:

Any action plan should incorporate the 30/30 Rule.  Lightning can strike more than 10 miles away from the center of a thunderstorm, beyond the audible range of thunder.  Therefore, if you hear thunder, you are within striking range of the storm. 

The 30/30 Rule states that people should seek shelter if the "Flash-To-Bang" delay (length of time in seconds from the sight of the lightning flash to the arrival of its subsequent thunder), is 30 seconds or less, and that they remain under cover until 30 minutes after the final clap of thunder. 

A 30 second lead time is necessary prior to a storm's arrival because lightning often strikes ahead of the storm center.  A 30 minute wait after the last thunder is heard is necessary because the trailing storm clouds still carry a lingering charge.  This charge can and does occasionally produce lightning on the back edge of storm, several minutes after the rain has ended.

SIDE NOTE:  It is important to remember that the 30/30 rule has a limited effect if storm clouds are building overhead.  If this is the case, you may not have the benefit of hearing the storm "move in".  The first indication of a lightning threat may very well be a strike in your immediate vicinity.  Keep an "eye on the sky" if clouds begin to build and darken!***

The following safety guidelines are broken down for individuals, small groups and large groups.  It is recommended that you read all of the safety guidelines.

Safety Guidelines: For Individuals

Plan Ahead!  Make sure you get the weather forecast before going out.

Carry a NOAA weather radio (which can be purchased at most electronics stores) or a portable radio with you on your travels, especially if you will be away from sturdy shelter (such as boating, camping, etc.).  This way you will always be able to get the latest forecast.

If thunderstorms are expected and you go ahead with your planned outdoor activity, have a lightning safety action plan in case thunderstorms threaten.  Remember, the keys to your safety plan lie in the answers to the following questions:  How far away am I from a safe enclosed structure (or enclosed vehicle)? and; How long will it take me to get to this safe location if storms threaten?

It is recommended that if the time delay between observing a lightning flash and hearing its subsequent thunder is 30 seconds or less, or if thunderclouds are building overhead, you should implement your lightning safety action plan  without delay!

Remember the "Flash to Bang" method to estimate lightning from your location - If you see lightning, count the number of seconds until you hear thunder. Divide the number of seconds by five (5) to get the distance the lightning is away from you.

    Example:

If you see lightning and it takes 10 seconds before you hear the thunder, then the lightning is 2 miles away from you (10 divided by 5 = 2 miles, too close!!).

Do not resume the event until 30 minutes after the last thunder clap.
 

Safety Guidelines: For small groups  
 

The lightning safety action plan must be known by all members in the group.

Plan Ahead! Make sure someone in the group gets the weather forecast before going out.

Designate one of the members to monitor NOAA weather radio (which can be purchased at most electronics stores, such as Radio Shack) or a portable radio. This way you will always be able to get the latest forecast.

Once arriving on-site, determine how far away your shelter is in case lightning threatens.  Remember to account for the time it will require to get to your safe location.  If thunderstorms threaten, make sure someone in the group continuously monitors the sky for lightning.

It is recommended that if the time delay between observing a lightning flash and hearing its subsequent thunder is 30 seconds or less, or if thunderclouds are building overhead, the group should implement the lightning safety action plan without delay!

Remember the "Flash to Bang" method to estimate lightning from your location - If you see lightning, count the number of seconds until you hear thunder. Divide the number of seconds by five (5) to get the distance the lightning is away from you.

    Example:

If you see lightning and it takes 10 seconds before you hear the thunder, then the lightning is 2 miles away from you (10 divided by 5 = 2 miles).

Do not resume the event until 30 minutes after the last thunder clap.
 

Safety Guidelines: For Large Groups
 

The lightning safety action plan should be used by all event organizers.

Plan Ahead! Make sure the event organizers responsible for safety get a good weather forecast before the event begins.

Safety organizers should monitor NOAA weather radio (which can be purchased at most electronics stores), or a portable radio or local cable, radio or TV broadcasts..

Since it may take considerable time to evacuate people to a safe location, personal observation of the lightning threat is not adequate (especially for fast moving lightning storms).  Professional lightning detection should equipment be made available so that the lightning threat can be observed significant distances from the event site.  Event organizers should know how long it will take to get people to safe shelter.

SIDE NOTE:  Lightning detection technology and instrumentation can be quite effective.  Current lightning detection equipment can be used to observe the location and direction/motion of lightning storms, and can be used to extrapolate their arrival.  Detectors also have the added benefit in that they can help determine when the threat has ended (remember - it is recommended that an event should not resume until after 30 minutes after the last audible thunder).  However, they CANNOT GUARANTEE SAFETY, especially when storms are developing overhead!  Do not let detectors override common sense! 

The time needed to properly evacuate an area increases proportionally to the number of people involved.  As the time requirements increase, the distance at which lightning is considered a threat must also increase (remember - it is suggested that people should be in safe shelter when the approaching storm is 6 miles away from the events location).  It is up to the event organizers to decide how close the lightning can get before warning "alarms" are issued.  This will depend on storm motion, direction, and the time it will take people to get to safe shelters.

    Example:

You are a safety coordinator for an outdoor high school reunion.  You are aware of a storm which is moving east at 30 mph towards your location, and the storm is 30 miles west of you.  You know it will take approximately 10 minutes to get people into a safe location.  How close should you let the storm get to your location before issuing the "lightning alarm"?

First, you know that people should already be in safe shelter when lightning is within 6 miles of the event site. If the storm is moving east at 30 mph, then it is moving 1/2 a mile per minute.  In the 10 minutes it takes to seek safe shelter, the storm will move 5 miles  [ 1/2 (mile/min) x 10 (minutes)  = 5 miles ].  Based on this storm motion and the time it takes people to get into shelter, the warning should be issued when the storm is 11 miles (5 miles + 6 miles = 11 miles) away from the event site.

With a large group of people, safe sites must be identified beforehand, along with a means to route these people to the safe locations (school buses are excellent lightning shelters and they can be placed at strategic locations, especially if nearby substantial shelters are not available).

Event organizers should consider placing lightning safety tips on game programs, score cards, etc.  Lightning safety placards set up in strategic locations are an effective means of raising awareness and communicating the lightning threat to the general public.

Important caveat

There is one very important caveat to the above safety plans:  lightning can and occasionally does strike many miles away from its parent thunderstorm.  In fact, there are documented cases in Florida where lightning has struck the ground more than 25 miles away from the thunderstorm center!  It is believed that quite a few people who are struck by lightning are struck by these rogue flashes (known as "bolts from the blue").  More information about "bolts from the blue" can be found at the end of this document.

First Aid for Lightning Strike Victims

Most people struck by lightning are not struck directly, but are affected by the current running through the ground (also known as a "side flash").  People who are adversely affected by a lightning flash, either directly or indirectly, need prompt medical attention:

Call 911.  Provide directions and information about the likely number of lightning strike victims;

The first tenet of emergency care is "make no more casualties".  Any rescuer must be aware of the continuing  danger that a lightning storm poses to the rescuers as well as to the victim(s).  If the area is a high risk area (mountain top, open field, etc.), it may be better that the rescuers who are in a relatively safer area wait until the danger has passed before exposing themselves.

It is relatively unusual for victims who survive a lightning strike to have major fractures that would cause paralysis or major bleeding complications unless they have suffered a fall or have been thrown a long distance.  Therefore, if  rescuers choose to expose themselves to lightning during an active storm, it would be better to move the victim away from a high risk area (such as under a tree, etc.) rather than give medical attention at the spot of the initial flash.  Rescuers are reminded to stay as low as possible and provide as little area to the ground surface as possible.

If the victim is not breathing, provide mouth to mouth resuscitation.  If the victim has no pulse, (check for the pulse at the carotid [neck] or femoral [knee] artery for 20 -30 seconds), then start CPR.  If the area is cold and wet, put a dry article of clothing between the victim and the ground to decrease the threat of hypothermia, which can complicate resuscitation.

Other important tips

If you are caught out in the open during a storm, stay away from tall, exposed objects (even if they offer shelter from the rain) or away from open areas (such as lakes, beaches, etc.).  Past history has shown that many people struck by lightning in Florida were near water, in an exposed location, or under/near trees.  If you are caught in the open and lightning is nearby, the safest position to assume is the Lightning Crouch.  Crouch down on the balls of your feet, keeping them as close together as possible.  Cover your ears, and do not allow other body parts to touch the ground.  Keep in mind that this position should be used only as a LAST RESORT!   It WILL NOT guarantee safety!

Why is it important to crouch down on the balls of your feet?  The reason is that when lightning strikes an object, the electrical discharge does not necessarily go down into the ground immediately.  Quite often the electricity will travel along the surface of the ground where the flash makes contact.  Many people "struck" by lightning are not hit by the flash directly, but are affected by the electricity of the flash as it travels along the surface of the ground (this is especially true if the ground is wet).  By keeping the surface area of your body in contact with the ground to a minimum (that is, keep your feet together and do not allow any other part of your body to contact the ground), you  reduce the threat of the electricity traveling across the ground from affecting you.

Mariners who are caught in a storm in a boat which does not have an enclosed cabin should crouch as low as possible in the center of the boat.  Do not use electronic equipment (except in an emergency).  Stay away from tall objects (masts, etc.).  All boats should be properly grounded.

A study of victims struck by lightning in Florida:

A recent study which analyzed lightning strike victims in Florida found that most were young males.  The most common activities people were involved in when struck were related to employment, and then recreation.  It also was found that most people were struck either prior to the storm (rain) reaching their location, or after the storm (rain) had ended.  Most of the people struck were either near water or near/under trees.

Results of this study indicate that people do not seek safe shelter early enough, or resume outdoor activities too soon after the storm (rain) has ended  (See The 30/30 Rule). 

For more information about "bolts from the blue", click here

Most of the information above was gathered from the Lightning Safety Group (LSG) which convened during the 1998 American Meteorological Society's annual meeting.  LSG consists of leading lightning experts across the United States.

5/18/01 DLJ