It takes two things to make a sneaker wave deadly if not dangerous, the deceptive and the deceived - the beguiling water and the human who is too near it.
I can easily imagine walking along the waterline of a beach on a day when the waves slowly lap ashore, soft as ducks. The quiet rhythm lulls me into a sense of security and I allow my attention to drift from the water to a friend walking with me or maybe my children goofing off or maybe just the music player on my phone.
I've taken my eyes off the water, and suddenly, improbably, a seething wall of water blasts me from the side, surges up my torso, knocks the air out of my chest with its shocking chill, soaks my clothes with gallons of water and fills every opening in them with wet sand, pinning me down so that I cannot escape.
The weight of the sand and water has crippled me. I cannot fight the still-surging wave; I cannot gain my footing and walk up the beach; I am anchored down at best, even worse is if I've been swept off my feet and tossed in the surf; worst of all is if I've been plunged underwater, the current jetting saltwater up my nose and down my throat, my life now at risk. Especially unlucky for me is if I've chosen a steeply sloped beach and/or the wave is dashing me against logs sent afloat or boulders on the beach.
If I'm working especially hard to win a Darwin Award, this has all happened atop a jetty, and the wave sends me over the wall: my head could be bashed against a rock, my limbs could get tangled in the riprap, the weight of the wave could thrust me down to the seafloor in seconds.
As noted in the first installment of Vista Point's series on sneakers ("Science of sneaker waves: Seeing isn't always believing," March 5, 2013), fatalities on North Coast beaches and jetties are more common when seas generally appear calm, not when the surf is high, presumably because it's not immediately obvious the beach or jetty is unsafe.
So how can you judge when the beach is safe?
Although there is no ironclad guide to when the surf is at its sneakiest, there are a few things to look out for, according to Troy Nicolini, National Weather Service meteorologist.
When the intervals between waves are inconsistent (it can take several minutes of watching the water to ascertain if this is happening) and all of them have more or less the same direction, there is a greater likelihood some of the waves will fuse their energy, metastasizing into much larger waves than those that preceded for as much as half an hour. The most critical factor is the interval between waves. Long-period waves, (generally from the mid-teens up, in seconds) actually move faster than short-period waves. Long-period waves pack a lot more energy, and although they may appear flatter because of the wide troughs between them, they can in fact be much taller than they seem.
A handy reference is the NWS marine forecast, available athttp://www.wrh.noaa.gov/eka/marine/, where you can check wave direction and interval for a sense of what to expect.
Also, sneakers are most likely fall through spring. In summer, waves are generally smaller, more locally generated, and they have a steadier wave pattern.
But, says Nicolini, "there's always a risk of being surprised by a wave."
The safest thing to do is to always appreciate that the ocean is an unpredictable thing and observe a few safe practices when near it: never turn your back on the ocean, keep some distance between you and the waterline, choose your beach well (steep beaches aren't as safe as flat beaches like Crescent City's South Beach), and don't go after dogs - dogs don't know beach safety rules, but they're much better swimmers than their awkward paddling might suggest, and with few exceptions canines swept off the beach are soon canines safely back on the beach, wetter and maybe a little wiser.
In November an Arcata family ran afoul of at least two of these guidelines and lost three lives by going into the water to try to save their dog, which had been swept off Big Lagoon Beach, a steep beach where sneaker waves can more easily trap people. Given the unsafe contours of the beach, it's also possible that the family was too close to the waterline.
After reviewing the safety guidelines, I must admit that I felt fairly unnerved by the whole idea of enjoying the beach as I used to.
Beach safety rules (like any safety rules, really) can sound excessively cautious, and anal-retentive, like scare tactics an oft-unheeded schoolmarm would repeat too often, damaging her credibility.
The problem with warnings is that they are always designed to protect people from worst-case scenarios and in the process the warnings discredit themselves with their own extremism. Never turn my back on the water? Really? Never? Is that even possible? Should I walk backwards when leaving the beach? Stay higher up on the beach? Why even bother being on the beach if I can't get close enough to the water to really feel its presence. (Plus, who other than masochistic runners wants to trudge through shifting dry sand?)
Nicolini offers a few words of comfort on this point. Although he behaves more cautiously near the water then he used to - generally walking a little higher up the beach, for example, he says it's still possible to enjoy the beach and even get your feet wet worry-free.
"I walk along the waterline too. On a personal level, I love the water. But there really are days that can fool you," he says. "So it takes about 20 minutes to get a sense of how safe the surf is. You really need to watch the ocean to be sure. Don't just take a glance and then turn your back on it and discount it. Just be aware and respectful of it and know it may surprise you. And if you're going to be a little distracted (talking to someone, playing with your iPod), stay a little farther from the water."
I can live with that.
Just down the highway is the one more Vista Point looking at sneaker waves. Stop by again for a view of how sneaker waves make all the difference in the world in distinguishing beach safety from jetty safety.
Reach Matthew C. Durkee at firstname.lastname@example.org.