Update: On Saturday, via Twitter NWS issued a stern and alarming warning about the incoming storm, telling Bay Area residents to stay away from beaches or else “risk certain death.”
For your own safety, please adhere to the the warnings and keep to higher ground all day Sunday and Monday.
HIGH SURF WARNING continues in effect along the coast from Sonoma County through Monterey County 9 AM Sun to 9 PM Mon.— NWS Bay Area (@NWSBayArea) December 15, 2018
STAY WELL BACK FROM THE OCEAN OR RISK CERTAIN DEATH. pic.twitter.com/VNroxlXdJs
The storms forecast to pummel the Bay Area this weekend—one Friday night and a second, much larger one anticipated Sunday—will bring a particularly dangerous element to San Francisco’s coastline, as the National Weather Service [NWS] warns of huge and potentially deadly waves.
NWS is predicting a “very large west-northwest swell late [in the] weekend.” According to science info site Sciencing, “swells are collections of waves produced by storm winds raging hundreds of miles out to sea, rather than the product of local winds along beaches.”
The NWS forecast warns that this weekend will be the “largest wave event this season” on SF shores, with “large breaking waves” ranging from 25 to 50 feet in height, or even exceeding that in “favored locations.”
According to the wave warning:
A potent storm system [...] will create a dynamic fetch zone where the strongest winds of the storm system will continuously increase the energy within a swell train on the storms southern flank, resulting in a very large, long period wave train aimed at the California coast. [...] The largest waves are then forecast to arrive Sunday night through Monday morning, with peak swells of 17 to 21 ft at 19 to 21 seconds expected.
The advisory adds, “NEVER turn your back on the ocean.”
Although the promise of monster waves may sound attractive to surfers, it is wisest to stay away from beaches during such a storm.
As the San Francisco Chronicle reported 20 years ago, Ocean Beach offers particularly pronounced dangers with “some of the deadliest riptides in California.”
Less than a week ago a surfer died at Ocean Beach in the midst of “waves [that] swelled to 10 feet.”
Although drowning deaths are relatively rare in general—NWS recorded 97 so far nationwide at the end of November—earlier this year the US Lifesaving Association, a non-profit group for lifeguards, declared Ocean Beach possibly the deadliest beach in the state.