San Francisco Warned 16 Foot Waves Could Pull People Off Beach Into Ocean

A stock image of the Golden Gate Bridge in Marshall’s Beach, San Francisco, California. A high surf advisory was in place for all San Francisco Pacific Coast beaches on Tuesday. lucky-photographer/Getty

A high surf advisorywarning beachgoers of large waves with the potential to pull people into the ocean was in effect for all Pacific Coast beaches in the San Francisco, California, forecast region on Tuesday.

The National Weather Service (NWS) office for San Francisco issued the advisory on early Tuesday morning. The alert will remain in place until 6 a.m. local time on Wednesday morning,

"Dangerous swimming and surfing conditions and localized beach erosion. Large waves can sweep across the beach without warning, pulling people into the sea from rocks, jetties and beaches," the advisory said, adding that waves were measuring between 14 and 16 feet.

"Sudden immersion in cold water can result in cold water shock even for the most experienced swimmers," the advisory added. "Cold water shock can result in dramatic changes in breathing, heart rate and blood pressure, greatly increasing the risk of drowning in rough open waters."

The advisory added that northwest-facing beaches had the highest threat for "large turbulent shore break and strong currents."

The advisory was in place for San Francisco Coastal North Bay Including Point Reyes National Seashore, San Francisco Peninsula Coast, Northern Monterey Bay and Southern Monterey Bay and Big Sur Coast.

Inexperienced swimmers should avoid going into the ocean during the advisory, the NWS said. Beachgoers also were warned to keep their pets away from the ocean.

NWS meteorologist Dylan Flynn told Newsweek that a storm-force low pressure system offshore in the Pacific Ocean caused high winds that generated the waves. The winds won't reach the California coast, Flynn said, but the waves will.

The winds were associated with the same system that brought an atmospheric river that struck the Pacific Northwest over the weekend. Flynn said the waves were generated 24 hours ago, and they took a day to reach the shore.

Normal deep water waves are around 10 feet high this time of year, Flynn said. Currently, the deep water waves are measuring 17 feet. Waves can break up to 200 percent higher than their deep water height.

Though the advisory is going to expire Wednesday morning, Flynn warned another high surf advisory will be issued for Thursday, when more large waves arrive. The waves will be generated on Wednesday with a new storm system and then will make their way to shore.

Another atmospheric river is expected to impact the Pacific Northwest through Thursday, bringing heavy rain and snow to northern California, Oregon, Washington, Idaho and western Montana.

Atmospheric rivers are a "long, narrow region in the atmosphere—like rivers in the sky—that transport most of the water vapor outside of the tropics," according to the National Oceanic and Atmospheric Administration.

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