Just about 80 percent of all deep-water ocean waves or a swell that hasn’t felt the ocean floor arriving along our rugged coastline come directly from the northwest.
That increases to 95 percent for a swell that is 20 feet or higher.
Those are the types of waves that can damage piers and other marine structures. These frightfully powerful waves are generated by enormous northern Pacific storms that often contained hurricane force winds.
As northwesterly swells start to feel the sea floor they become shallow-water waves as they bend around the Point Estero and the Harmony Headlands and diminish in height due to refraction and diffraction. This phenomenon creates a shadow zone in the northern end of Estero Bay where the Cayucos Pier is located.
This is an important reason why the Cayucos Pier was built in its current location and why it continues to remain standing over the decades. The pier at Cayucos along with the Hartford Pier at Port San Luis are usually the most sheltered along the Central Coast from damaging waves, but in early March of 1983 no location was immune.
One of the strongest El Niño events in California history was in full swing that month with much warmer than average seawater temperature in the eastern Pacific producing a greater amount of evaporation and convection.
That allowed the jet stream to take a more southerly route. This condition caused winter storms to come in from a west-southwesterly direction. Consequently, the ocean waves that these storms generated approached our rugged coastline directly from the southwest as opposed to the normal northwesterly direction. The southwesterly waves experienced little loss in wave energy before slamming into the coastline.
In fact, the topography of the ocean floor near Avila Beach and Cayucos can amplify the wave heights from this direction. It was estimated that on March 1, 1983, significant swell height (the average height of the waves in the top third of the wave record) reached 27 feet with a 19-second period at the Diablo Canyon waverider buoy, a few miles north of Avila Beach. This swell event destroyed the 2,700-foot-long wooden Unocal Pier in Port San Luis.
The Cayucos Pier was also damaged and required emergency repairs, but it held fast at the peak of the storm.
The iconic Cayucos Pier has become a treasured place to enjoy spectacular views of the Pacific as you walk toward the sea and of Cayucos as you walk back. Each Memorial Day the "Lost at Sea Memorial" is held there.
Over the years the Pacific has taken its toll on the pier. The Cayucos Pier Project is a nonprofit group that is collecting funds to help rebuild it. To learn more visit www.savecayucospier.org/.
Land stewardship is important to PG&E. The company manages 12,820 acres that surround Diablo Canyon Power Plant. This has allowed for coastal hiking trails open to public use, including the Pecho Coast Trail that leads to the restored Point San Luis Lighthouse. To learn more about these preserved lands, visit www.pge.com.
John Lindseys column is special to The Tribune. He is a media relations representative for PG&E and a longtime local meteorologist. He is president of the Point San Luis Lighthouse Keepers. If you have a question, send him an email at firstname.lastname@example.org.