Central Florida is not the only area reeling with coastal flooding during times of high tide. Much of the California coastline is bracing for more rounds of record high tides: flooding homes and businesses. However, unlike Florida, King Tides have nothing to do with it… yet.
Coastal Flood Advisories extend from the San Diego coast all the way to the San Francisco Bay Area. San Diego and Los Angeles both recorded high tides over 8ft on Wednesday! San Francisco registered its highest reading ever for the month of October Wednesday, clocking in at 7.96ft. That is 2.01ft of inundation!
Los Angeles has logged 12 coastal flood days so far this year, more than any year going back the last 50 years! Even more are expected and there is a specific culprit… El Niño!
Due to the unprecedented El Niño, the Pacific has seen a record-breaking oceanic heatwave, resulting in a high amount of thermal expansion.
One of the biggest threats for coastal flooding the west coast will continue to deal with are Kelvin Waves. A Kelvin Wave is a massive underwater band of warm water that travels from west to east along the equatorial Pacific, reaching the west coast of South America. After colliding with the South American coastline it surges northward, riding up the coast of California all the way up to Alaska. Due to the “bowl-like” shape of the Southern California coast, this surge of water tends to get trapped along the coastline, exacerbating the effects and timeline of these anomalously high tides.
Kelvin Waves do not look like a normal cresting waves. Instead, they move just below the surface, increasing the swells from underneath and raising water levels. These waves happen frequently during El Niño years.
The current coastal flooding California is facing is not due to King Tides. California’s King Tide season begins around the Thanksgiving holiday and lasts through January. If a King Tide pattern aligns with a Kelvin Wave, the two combined could increase high tides up to 5ft above normal levels.
The other impact Southern California will face thanks to El Niño is an overactive Pacific Subtropical Jet Stream. This will bring more frequent storm systems causing onshore winds and heavy rainfall, both of which will exacerbate the coastal flood threat already faced up and down the coast.