The U.S. National Weather Service issued a Beach Hazards Statement at 7:01 p.m. Pacific time tonight, and they say it is effective until 9:00 p.m. tomorrow evening, Wednesday, March 12, 2014.
The USNWS said the San Franciso Bay Area has issued a Beach Hazards Statement for "sneaker waves" and rip currents. Sneaker waves are waves that come to the shore train-like, become increasingly bigger and then of course drag whatever is on the shore into the ocean.
Winter season is the most dangerous time of year for these waves. They are disproportionately large waves that appear suddenly and without any warning. Since they are unexpected, they represent a serious hazard to both people and ship traffic. Some regions of the world are more prone to these waves than others, leading to posted warnings and advisories to make visitors aware of the issue.
Unlike a tsunami, there is no chance of predicting a sneaker wave. They form when several smaller waves combine their energy, creating a single big wave. This can happen as a result of the disruption of ocean currents, or because of subtle changes in weather and topography. They follow no known pattern, and they will interrupt the established wave pattern. They are strong enough to kill an adult.
This warning is for the entire coastline area from Sonoma County south through Monterey County.
State officials say the rip currents and sneaker waves in these areas tomorrow means that potentially dangerous conditions may exist on specific beaches. These hazards may include large shore breaks, coming along with those strong rip currents.