A wave crest nearly reaches the deck of the Cayucos Pier, with spray shooting several feet above it on Dec. 23. Calmness between the swells shows how far the water level was from the pier’s base. Since 1991, I’ve been forecasting waves along the Central Coast, but the recent swell event marked the longest period/wavelengths I’ve ever observed. The waves were immense and powerful, breaking with extraordinary force. On Monday, Dec. 23, I captured these photos from Estero Bluffs State Park that illustrate the intensity of the event. One image shows a wave crest nearly reaching the deck of the Cayucos Pier, with spray shooting several feet above it, while the other highlights the calmness between the swells and how far the water level was from the pier’s base. The pier’s deck is around 20 feet above sea level. The timing of this swell event was fortunate, and here is why: the tide was only 2.8 feet at 3:15 p.m. when I took the photos of these massive, long-period waves striking the Cayucos Pier. Had the tide been higher — 6 feet or more, which is not uncommon — the pier could have sustained significant damage. Imagine a wave of this size riding on water levels three-plus feet higher. In a worst-case scenario, several factors coming together simultaneously could have partially submerged the pier during the crest of these extraordinarily long-period waves: 1) A 7-foot tide could have coincided with a two-foot storm surge from gale-force southerly prefrontal winds associated with an intense storm off the coast. Warmer seawater would cause thermal expansion of the water column, raising sea levels by another half a foot, which is often the case during El Niño conditions. Additionally, El Niño storms often generate swell trains from a west-southwest direction, allowing waves to […]