'King tides' are coming to California

Sunset at Pismo Beach in California
Sunset at Pismo Beach in California Mike Senese/Flickr Creative Commons

Heads up, high tides in California are about to get much higher than usual.

Starting around Dec. 30 and lasting until roughly Jan. 2, the ocean will experience a twice-yearly phenomenon known as the "king tides."

This occurs when the sun and moon sync up in a way that creates maximum pull on the Earth's waters.

Usually tides are highest when the moon is either full or new. The sun also affects tides, and it exerts the most influence when it is either closest or farthest from the Earth.

On Jan. 1, the new moon will occur during the period known as the perihelion, the point in the Earth's yearlong orbit when it swings closest to the sun. Both of these factors combine to create the winter king tides.

Ryan Kittell with the National Weather Service says tides are expected to peak on New Year's Day at 7.1 feet above the average low tide. That's about a foot and a half more than the average high tide in Los Angeles  Harbor.

Kittell added that Wednesday's swell is expected to be the highest high tide for all of 2014.

"So it's starting off with the highest, at least for the predicted high tides," he said. 

Still, he doesn't think flooding will be a problem this time, unlike last year, when parts of Seal Beach were inundated with water.

That year, the king tide reached 7.7 feet above the average low tide in part because a low pressure system was hovering in the region. This year, he says, that kind of weather is unlikely.

A citizen science project called the California King Tides Initiative is encouraging people to snap pictures of the super swells to help visualize what the coast would likely look like given sea-level predictions under climate change models. 

Sara Aminzadeh is with the organization, and she says that, by some estimates, sea levels could rise by a foot in the next 50 years. That means this winter's king tides may one day be the new normal.

She hopes that showing people pictures of what an extra foot of water means for the coast will help them understand the potential effects of climate change.

"Images are a really powerful mobilizing tool," she said.

Highest tides are expected around 8 a.m. on Jan. 1.

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