After setting out under benign summer skies on a late afternoon hike, my husband and I reached a ridge crest in the Franklin Mountains of western Texas, only to discover a most unwelcome sight on the other side: thunderstorms, crackling with lightning and moving quickly in our direction. That day we were lucky. We scampered off the peak, trailed by rounds of thunder but without our hair standing on end, and gave thanks that we were on a dayhike. On the drive home, I thought about all those years of backpacking above treeline, and wondered: What should we have done if we'd been up high, days from shelter, and loaded down with heavy packs?
The short answer: There's no prescription that guarantees complete safety when you're in the backcountry and bolts of electricity dance around you. The only foolproof way to avoid lightning is to avoid thunderstorms, which is easy when you're at home and can flick on The Weather Channel. But in the backwoods, being able to judge conditions from the ground requires knowledge and experience. Which may be why so many backcountry travelers--and wilderness educators--have come to rely on two practices that are convenient and easy to remember, but which lightning-safety experts say provide dubious protection from lightning strikes.
Wilderness educators have long recommended placing a nonconducting object between your body and the ground to keep you from being zapped by ground currents (electricity that travels through the ground from a nearby strike). Items most often cited for use include a closed-cell foam sleeping pad, a coil of climbing rope, or your pack, frame side down.
Such advice is dismissed by experts like Ron Holle, of the National Severe Storms Laboratory in Norman, Oklahoma, and the National Lightning Safety Institute (NLSI), and Mary Anne Cooper, M.D., a doctor of emergency medicine at the University of Chicago who's also a member of the NLSI and the Lightning Safety Group, a collection of experts who met in 1998 to establish nationwide lightning-safety recommendations.
"There is a great deal of wishful thinking in the outdoors community that sitting on a backpack or putting down metal can reduce or eliminate lightning danger," warns Holle. "Unfortunately, it doesn't matter what you're sitting or lying on. The flash came from 5 to 8 miles up in the cloud and has 30,000 amps, so it will penetrate absolutely anything. Go to a substantial building or metal-topped vehicle."
Sound advice if you're near shelter or a car, but that isn't likely 10 miles into the mountains. "In a high-risk situation, assuming the lightning-safety position on some kind of insulating material may offer the right person at the right time some protection," says Eric Johnson, M.D., a physician in Idaho who specializes in outdoor medicine and training. It can't hurt in other words.
Cone Of Protection
If the issue of insulation generates sparks, then the "cone of protection" unleashes a firestorm of highly charged opinion. To visualize the cone, imagine the height of a pinnacle or tall tree, and use that height as a radius to create a circle around its base. The theory is that within the perimeter of this circle, you're too far away from the tall object to be affected by "splash" or ground currents, yet not so far as to be an alternate target for a strike. Some sources say the object must exceed 100 feet in height for this theory to be effective.
The concept may have emerged from research into protecting structures with lightning rods, with the idea being that larger structures require taller, or multiple, lightning rods for protection. It's also often used as a recommendation for boaters, but it's important to note that masts or antennas can be grounded to conduct and dissipate a strike. A kayak or canoe does not have that option.
The folks at the National Outdoor Leadership School (NOLS), while warning that this is a very controversial topic, point out that at times, large topographic features have seemed to offer relative protection in the same way as tall artificial structures. Even so, there is no evidence that it works.
"I believe the cone of protection is a total fallacy that we should avoid mentioning ever again," says Dr. Cooper, citing a study refuting the cone theory's utility based on the burgeoning population of metal towers across the country. NOLS, meanwhile, continues to study the topic.
"Unfortunately we can't do double-blind studies to see what works. My recommendations and those of NOLS are based on anecdotal experience,"
Dr. Johnson observes.
What to do?
So, the question remains: What can you do to stay lightning-safe in the backcountry? Your first and best option, all experts agree, is to stay clear of high-risk areas when thunderstorms are likely. In that respect, one weather pattern that rarely differs, regardless of region of the country, is that mountains in summer breed late-afternoon thunderstorms generally between the hours of 2 and 6 p.m., according to the NLSI. As the day winds on, avoid high ridges and mountaintops (especially those that hide your view of oncoming storms), exposed areas, and lakes. Or simply follow the "summer in the mountains" rule: up high by noon, down low by two.
It also helps to know the "flash to bang" method of calculating how long it'll take an approaching storm to reach you. Simply count the number of seconds between the flash of lightning and the crash of thunder. Five seconds equals a mile. Keep in mind that a storm can advance 6 to 8 miles between lightning strokes, and that lightning strikes have been documented 10 miles in front of a storm. In other words, don't assume you can ignore thunderclouds just because they're way off in the distance. If you can still count seconds between flash and crash, you have time to get to a safer spot. Do it, then wait until 30 minutes after the storm passes to head out again.
The NLSI and the Lightning Safety Group recommend avoiding isolated trees, metal (pack frames, even), and small shelters during a thunderstorm. They also advise against touching dissimilar objects, like rock and ground or tree and ground. Seek out clumps of shrubs or trees of similar height. Tents offer no safety on open ground.
If you take all of the above-mentioned precautions, you'll increase your odds of staying safe. But if your hair stands on end, metal objects or wet rocks hum, and you notice the smell of ozone or a bluish tinge of St. Elmo's fire around boulders or a person, you're being warned. The clouds and ground are negotiating a target for a lightning strike, and you don't want to be it.
If you are ever caught without shelter in a thunderstorm, experts recommend crouching in the "lightning-safety position" with only your feet contacting an insulation material placed on the ground. The logic behind this position is that you're lowering your height (and therefore propensity to attract lightning), as well as reducing your contact with the ground and your vulnerability to ground currents. Keep your feet together, and space people in your group at least 15 feet apart--NOLS recommends 30 feet--so that not everyone is hit. Cover your ears to minimize hearing damage from thunder shock waves.
Lightning-knowledgeable people use words like "capricious," "random," "unpredictable," and "erratic" when describing the way the bolts behave. They also acknowledge that when you're outdoors, there's no absolutely safe place to be. You'll be at risk regardless of your location. But we all accept a certain level of risk when venturing into the wilderness. The best thing to do is face up to the possibilities of what can go wrong, prepare as best you can with knowledge and information, stay aware of weather conditions, and if the worst-case scenario does unfold, head to safety.