Education and prevention are the keys to lightning safety. The Tahoe Open Water Swimming Association (LTOWSA) provides several prevention strategies in response to lightning hazards. We have developed the following lightning strategy to mitigate the risk of a lightning hazard while a marathon swim attempt is underway or an escort vessel is on the water navigating to/from a marathon swimming course. The Sierra and Lake Tahoe Basin are prone to thunderstorms, especially in the afternoon, which creates a significant safety issue.
Lightning Strike Policy
Thunderstorms with lightning make the lake unsuitable for swimming. Lightning is a significant threat to swim attempts. LTOWSA observers and vessel captains must monitor warnings of threatening weather if a swim attempt is underway.
POLICY: LIGHTNING WITHIN 6 MILES OF THE SWIMMER/ESCORT VESSEL SHALL RESULT IN THE ATTEMPT BEING ABORTED. THE ESCORT VESSEL MUST THEN NAVIGATE TO THE NEAREST, SAFEST DEBARKATION LOCATION AS SOON AS POSSIBLE.
STRIKE DISTANCE THRESHOLD: A strike within six miles as measured by a lightning location app or with the ‘Flash to Bang’ method poses a high risk to an attempt. An approximate 6-mile distance is measured between a flash and a bang after 30 seconds (See Table 1 below for further details).
Lightning awareness should be heightened at the first flash of lightning, clap of thunder, and/or other signs of an impending storm, such as increasing winds or darkening skies, no matter how far away. These activities should be treated as a warning or wake-up call to the crew, observer, and escort vessel captain. Lightning safety experts suggest that if you hear thunder, prepare for evacuation.
Evacuation and Stike Safety Locations
It is the captain of the vessel’s responsibility to know where the closest “safer structure or location” is to the course and know how long it will take to evacuate everyone to that safer location. Once on land, it is recommended that all depart to a safer structure or location. A safer structure or location is defined as any building normally occupied or frequently used by people, e.g., a building with plumbing and/or electrical wiring that acts to ground the structure electrically. Avoid the shower, plumbing facilities, contact with electrical appliances, and open windows and doorways during a thunderstorm Without a sturdy, frequently inhabited building, any vehicle with a hard metal roof (neither a convertible nor a golf cart) with the windows shut provides a measure of safety. The hard metal frame and roof, not the rubber tires, protect occupants by dissipating lightning current around the vehicle and not through the occupants. It is important not to touch the metal framework of the vehicle.
Response to Someone Being Struck
People who have been struck by lightning do not carry an electrical charge. Therefore, cardiopulmonary resuscitation (CPR) is safe for the first responder. An injured person should be moved to a safer location before starting CPR. Lightning strike victims who show signs of cardiac or respiratory arrest need prompt emergency care. Call 911 and activate your emergency action plan immediately. Prompt, aggressive CPR has been highly effective for the survival of victims of lightning strikes.
Table 1. Flash to Bang Method
To estimate the distance between your location and a lightning flash, use the “Flash to Bang” method: If you observe lightning, count the number of seconds until you hear thunder. Divide the number of seconds by five to obtain the distance in miles. Example: If you see lightning and it takes 10 seconds before you hear the thunder, then the lightning is 2 miles away.
|If Thunder is heard||The Lightning is…|
|5 seconds after a Flash||1 mile away|
|10 seconds after a Flash||2 miles away|
|15 seconds after a Flash||3 miles away|
|20 seconds after a Flash||4 miles away|
|25 seconds after a Flash||5 miles away|
|30 seconds after a Flash||6 miles away|
|35 seconds after a Flash||7 miles away|
|40 seconds after a Flash||8 miles away|