Tuesday, December 24, 2013

Sunshine and Calm = Sneaker Waves.

Posted By on Tue, Dec 24, 2013 at 12:59 PM

click to enlarge Agate Beach. - PHOTO BY KEN MALCOMSON
  • Photo by Ken Malcomson
  • Agate Beach.

Here on the Humboldt edge  of  the  world, Christmas  Day and the day after promise to be filled with sunshiny sparkle and gentle breezes. To the beach,  the  wonderful beach!

Yes, by all means, go, enjoy. But, before you go, you should  do something that could save your life and that of others: Read the sneaker wave tips (below) offered by the good folks with the U.S. Coast Guard Sector Humboldt Bay and the National Weather Service office on Woodley Island. Then spread the word. Because sunny, calm days are the consistent backdrop for these watery surprises that have been known to  drag people and pets to an ocean death. As a news release from the Coast Guard emphasizes:

"Sneaker waves can catch you off guard and quickly pull you into the ocean where survival is unlikely because of strong currents, turbulent surf and very cold water. "

Grim. But real. According to Troy Nicolini, with the weather service, sunny, calm days have historically been the most deadly for beachgoers here on the North Coast (and jettygoers, although you really shouldn't be wandering out on those wave-bashed projections, anyway). Those are the days when people have died from sneaker waves, particularly during a rising tide — and as Nicolini explained in a previous Journal story, the waves that took them were not monsters, but rather no bigger than eight to 10 feet. There are several reasons for this seeming incongruity:

One, people tend to stay away from the ocean on stormy, high-surf days, because the risk is obvious; 

Two: Sunny, calm days lure more people to the beach;

Three: The gentle weather itself on these glorious beach days creates a wave-set pattern that produces "sneaker" waves;

Four: Part of this wave-set pattern lulls the unobservant into a false sense of regularity and calm.

As the news release explains:

"The sneaker wave threat is caused by long period waves that have set behavior, resulting in 20 or more minutes of smaller waves followed by the arrival of very large waves that strike without warning."

An excerpt from our earlier story explains further:

Aside from the tides, created by the moon's gravitational pull, and the occasional tsunamis, waves are born by wind pushing on the water and can come from any distance — from a thousand miles away, 60 miles, a couple of miles or from a storm right on top of you. Long-distance waves, which increase in height, wavelength and speed as they travel, can outrun shorter, locally produced waves.

"So on a day when lots of different waves exist, you've always got some adding up and some canceling out each other. And what you get is a really homogeneous wave through time," Nicolini said. "Ironically, these waves, they might be kind of big, but they all end up about the same when they hit the beach. Now, imagine a day where all the waves are coming only from far away — thousands of miles."

This turns out to happen on sunny days — no local storm, no local waves. These long-distance waves can look like one big wave, Nicolini said. But they are more like brother-sister waves — nearly identical, but traveling at slightly different speeds. They're recognizable by their long crests — the width of the wave from left to right as you stare at it from the beach. And because they have traveled far, and lost the push from their original wind, their profile may have smoothed out; from the beach, the ocean might even appear flat.

As they travel, at slightly different speeds, sometimes these near-identical waves are out of synch, and they cancel each other out, making smaller sets of waves. Other times they synchronize, or add up, for awhile, and produce a set of larger waves — sneaker waves, which, in Humboldt, have been known to sweep as far as 160 feet higher up the beach than the smaller set of waves before them.

There can be 20 to 30 minutes between the smaller wave sets and bigger wave sets. So here's what you do, says Nicolini: Don't stay away from the pretty, sparkly beach. Go, but once you're there study the ocean for about 30 minutes to get a sense of where the larger waves sets are hitting; don't, in other words, assume that the most recent wet line in the sand is the highest the waves are going to hit (that might be the small-waves line). Go with other people and watch the ocean for each other. And follow these other tips, courtesy the Coast Guard:

Choose your beach well. Steep beaches are particularly dangerous because the force of the ocean waves can reach much farther up the beach and pull you into the surf. Steep beaches also have course sand that washes out from under your feet making it hard to resist being pulled into the water. Flatter beaches are much better choices.

Avoid Rocks and Jetties. Rocks and jetties can give a false sense of security but sneaker waves can overtop them without warning.

Stay Back. Stay much farther back from the water than you might think is necessary. Sneaker waves often reach well into the dry sand part of a beach. And remember that rising tides can cause sneaker waves to wash even farther up a beach, and can cut off access around headlands.

Never turn your back on the ocean. The most dangerous thing you can do is to be near the surf with your attention diverted, but some beach activities require you to do exactly this. If you participate in such an activity, such as surf fishing, consider wearing a life vest to give yourself a fighting chance of surviving if you do get pulled in.

Don’t go in after dogs. Dogs that are pulled into the surf almost always get out on their own while their human rescuers usually do not … so stay on dry land and wait for them to swim back to shore.

Call 911. Don’t go into the water after a person who gets pulled into the surf. Remember that you will likely also get in trouble so that when rescuers do arrive they will have to divide their time between multiple victims. It’s much better to call 911 and be prepared to guide rescuers to the person in trouble.

and lastly: Share this message. Share this water safety message with your family and especially children. Also share it with friends and co-workers.
Even engage perfect strangers if you see them doing something dangerous.

Seriously, people, be careful out there. And really do be a busybody: Tell everyone you meet what you now know about sneaker waves.

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Heidi Walters

Heidi Walters worked as a staff writer at the North Coast Journal from 2005 to 2015.

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