You are using an older browser version. Please use a supported version for the best MSN experience.

Massive waves 25 to 40 feet expected to accompany Bay Area storms

SF Gate logo SF Gate 12/15/2018 By Gwendolyn Wu

a man riding a wave on a surfboard in the water: A surfer takes off on a large wave at Maverick's in Half Moon Bay, CA Wednesday, January 7, 2016.

A surfer takes off on a large wave at Maverick's in Half Moon Bay, CA Wednesday, January 7, 2016.
© Provided by Hearst Newspapers

A pair of storms is expected to slam the Bay Area coastline this weekend with monster waves as high as 40 feet, the biggest so far this year, prompting the National Weather Service to warn beach visitors to be extra careful around the water.

Light rain fell on Friday and some sprinkles may filter down on Saturday, but Sunday is when a second storm should sweep in with heavy precipitation, forecasters said. That will bring huge swells to the beaches, with towering waves possibly topping out at 25 to 40 feet.

The weather service also warned that gusty winds on Sunday may bring power outages and some coastal flooding.

The highest waves will probably be seen around Mavericks Beach off the northern coast of Half Moon Bay, where surfers are eagerly awaiting those 40-foot whoppers, said Roger Gass, a meteorologist with the weather service’s Bay Area office.

“They’re peaking at the time we’re going to be seeing rain, so that’s kind of one good thing, so to speak,” he said. “Most of the time, people aren’t at the coast when we have wet conditions.”

Forecasters warned that anyone walking to the beach should stay away from the sand and jetties, for fear of sneaker waves — or just getting caught unaware as the water swells. Waves could last up to 20 seconds and run up high on the coast, and there was an increased risk of rip currents on Sunday, according to the National Weather Service.

If the high surf continues into next week, surfers from around the world may show up for the Mavericks Challenge.

“We are closely monitoring the conditions to potentially run on Tuesday or Thursday next week,” said Mike Parsons, a commissioner with the World Surf League.

Friday’s storm developed over the North Bay and then moved south during the evening rush hour. The North Bay was expected to receive a quarter- to half-inch of precipitation by Saturday morning, while San Francisco and the Peninsula might have gotten closer to a tenth- to a quarter-inch.

Drivers should be cautious on the road over the weekend even if the storm is weak at times, Gass said.

Air quality levels briefly dipped to unhealthy levels for sensitive groups on Friday morning, as winds carried wood-burning smoke up from the San Joaquin Valley, air district officials said.

The Bay Area Air Quality Management District predicted that pollution levels would be even worse on Saturday, exceeding federal standards, and issued a 24-hour Spare the Air alert banning wood-burning in the region.

“Usually when we have storms, they can improve air quality because we get more wind,” said Kristine Roselius, a spokeswoman for the district. It remains to be seen if that happens this weekend.

Sunday’s storm is predicted to bring up to an inch of rain to San Francisco and spread further across the region on Monday morning. Some coastal spots in the North Bay may see up to 2 or 3 inches of rain.

This latest precipitation was welcome news for those worried by drier, drought-like conditions earlier in the year. A steady stream of storms in November brought the Bay Area closer to normal water year totals, but more was needed in many regions — and this weekend should improve on that. San Francisco was at 71 percent of average rainfall as of Friday.

Farther north, two weekend storms were predicted to move in over the Sierra Nevada, offering a chance of light snow over the highest peaks on Saturday and Sunday. By late this week, the snowpack in the Sierra sat at about 87 percent of average, said Chris Johnston, a meteorologist with the National Weather Service’s Reno office.

“This is important for more water resources, because the state of California almost entirely depends on snowpack for its water,” Johnston said.

Storms dumped nearly five feet of snow on Mammoth earlier this month, allowing ski resorts to open their trails to the public.

Gwendolyn Wu is a San Francisco Chronicle staff writer. Email: gwendolyn.wu@sfchronicle.com Twitter: @gwendolynawu

AdChoices
AdChoices

More From SF Gate

image beaconimage beaconimage beacon