(Bloomberg ) Northern California beachgoers are being warned that the Pacific can kill in an instant as powerful breakers known as "sneaker waves" surge ashore without warning and drag their victims to sea. Five people have died since November.
"Don't turn your back to the ocean," said Pamela Boehland, a Coast Guard spokeswoman in California.
Sneaker waves, which can be six to 10 feet high, originate in winter storms perhaps thousands of miles west of the U.S. coast, said Troy Nicolini, a meteorologist at the National Weather Service in Eureka, California. When waves travel long distances, they can group into sets with quiet periods in between, he said.
"When you have that wave arrive at our beach, they can look very benign," he said. "Then suddenly the very long, quiet period can be broken by a series of really big waves."
A man, a woman and their teenage son walking their dog were swept away at Big Lagoon Beach near Eureka, about 270 miles (438 kilometers) north of San Francisco. Another man died Jan. 1 when he and his wife went into the surf for their dog at Point Reyes National Seashore, north of the city. A woman perished Jan. 27 while walking with a friend on Black Sands Beach near Shelter Cove, south of Eureka, according to the Coast Guard.
Each of the deaths involved people walking their dogs or attempting to save dogs being swept out to sea, Boehland said. All of the pets survived.
"Don't go in after your dog, because dogs are typically better swimmers than people," Boehland said.
In California, the peak season for sneaker waves is from October to February, when there are more storms at sea in the Northern Hemisphere, Nicolini said. Similar waves are not as common on the East Coast, he said.
The weather service is using social media, including Twitter and Facebook (FB), to alert the public to beach hazards or high surf, said Kevin Baker, supervisory meteorologist at the National Weather Service forecast office in Monterey, California.