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A fierce and persistent storm off the Alaskan coast is churning water to dangerous levels across the Pacific Ocean – and generating massive surf along our coast.
Waves of 16 to 22 feet — formidable “triple overheads” — were predicted late Thursday and Friday in the San Francisco Bay region, creating hazardous conditions for seaside residents and visitors, according to the National Weather Service.
“We’ve had this super storm in the Gulf of Alaska, spinning systems down here,” said Jan Null of Golden Gate Weather Service.
“It’s just sitting there,” he said, “blowing over huge stretches of water over a long time, pushing out swells.”
This punishing storm has all the ingredients to create big surf: sustained high winds, prolonged duration and “fetch,” or how much surface water area the wind is blowing over.
The weather service advises people to stay away from the water’s edge and watch for exceptionally large waves, as the surf could produce rip currents and cause beach erosions.
The high surf advisory is in effect from 3 p.m. Thursday to 3 a.m Saturday morning. The northwest waves will come in 17-to 18-second intervals. Friday morning will present a six foot high tide at 10 a.m., combined with that rising swell. That’s the time to be especially careful where you’re standing.
It follows a Thanksgiving-week storm that drenched California and generated a monster 75-foot wave off Cape Mendocino.
“I won’t go out in waves like that,” said surfer Chris Witteman of San Francisco. “If you get caught, it’s like being inside a washing machine. You get the sh*t pounded out of you.”
At Montara State Beach, “they’re huge and foreboding,” said surfer Larry Miller of El Granada.Contest-worthy surf occurs when the NOAA buoys read 18 feet and an 18 second period.
On the north shore of the Hawaiian island of Maui, where the Jaws Big Wave Championship is being held, organizers predicted waves up to 45 feet.
By comparison, summer surf is what gives the Pacific its serene name. Those waves range from 4 to 8 feet high, said NWS meteorologist Spencer Tangen.
The big rollers are created by winter’s infamous “wave factory” in the Gulf of Alaska, thousands of miles away.
This time of year, low pressure systems from the north collide with high pressure systems from the south. The differential generates strong, fast winds.
Winds in the Gulf right now are measuring a punishing 65 to 72 miles per hour — hurricane force.
The rotating energy of this gyre is transferred to the ocean, where waves blow over miles, piling up into mammoth swells. Tides also affect the size of a wave: as a tide recedes and the seafloor becomes more shallow, the wave’s energy is intensified.
That’s why winter is the time for big-wave surf contests, like Mavericks. A channel on the Pacific Ocean floor magnifies these waves, which can reach up to 50 feet high.
The large surf can be extremely dangerous for beachgoers and sightseers who are not paying attention.
“The large breaking waves along the coast and on beaches will cause the waves to run further up beaches than normal,” warned Tangen. “They will wash over rocks.”
When admiring the power, he said, “people need to stay back away from the water’s edge — and watch from safe distance.”
