* WHAT. Long period northwest swell will result in an energetic surf zone resulting in an increasing risk of sneaker waves and increasing rip currents, then transitioning to a larger surf with strong rip currents, long beach run-up and large shore break on steeper beaches. Breaking waves of 10 to 14 feet are expected. * WHERE. San Francisco, Coastal North Bay Including Point Reyes National Seashore and San Francisco Peninsula Coast Counties. * WHEN. From Sunday afternoon through Monday evening. * IMPACTS. Large waves can sweep across the beach without warning, pulling people into the sea from rocks, jetties, and beaches. Sudden immersion in cold water can result in cold water shock even for the most experienced swimmers. 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.