Exceptionally high tides are expected to hit California as early as this weekend, forcing authorities to prepare for another onslaught along the state’s already battered coastline.
The National Weather Service issued a coastal flooding warning that goes into effect Sunday morning and lasts through Thursday afternoon, saying it expects “significant coastal flooding” in San Diego and Orange counties that will inundate low-lying homes, businesses and critical infrastructure, with some shoreline erosion in the mornings throughout the warning period.
Significant to moderate beach erosion is likely in Los Angeles, Ventura, Santa Barbara and San Luis Obispo counties, and “isolated damage to structures from seawater flooding is possible,” forecasters said. A coastal flood advisory was issued during the same period in these four counties.
“Take necessary steps to protect properties subject to flooding,” the weather service said.
In the San Francisco Bay and Monterey Bay areas, forecasters warned of flooding of up to 1.9 feet above ground level near shorelines and tidal waterways, with rising tides bringing waves farther than normal onto the beach, “restricting escape from beaches and coastal areas.” A coastal flood advisory for these areas comes into effect Saturday morning and lasts until Thursday afternoon.
The coastline has already been hit by an unprecedented confluence of threats this year: the arrival of El Niño off the coast of Peru, which fueled an unusually active hurricane season in the eastern Pacific Ocean; a long-standing and unrelated marine heatwave that ravaged the coastline for months, and a peculiar alignment of Earth, Sun and Moon observed only once every two decades.
And the threats can only intensify. Tides are expected to become even higher around Thanksgiving, Christmas and Martin Luther King Jr. Day. The coast could be particularly hard hit if unusually high king tides coincide with severe winter storms.
“It’s likely that things will get worse before they get better,” said Daniel Swain, a climate scientist at UC Agriculture and Natural Resources.
Tides could break modern records in San Diego and Orange counties in the coming days, the National Weather Service said. When adjusted for record ocean temperatures off the coast, tides could reach 7.5 to 8 feet or more above the baseline, which is defined as the average low water level observed between 1983 and 2001. (Warmer waters raise sea levels, as water expands as it warms.)
The water on the surface of Scripps Pier in La Jolla, a neighborhood of San Diego, reached a high point for the year of about 77 degrees, while the average high is about 70 degrees. On Thursday alone, the surface temperature there was about 73 degrees, well above the average of 66 for this time of year.
All of this is contributing to an unprecedented rise in sea levels. The National Weather Service says actual tides in Southern California are 1.25 to 1.75 feet higher than what would be expected from the position of the Earth, sun and moon alone, given warmer ocean temperatures.
“As far as I know, this is unprecedented, especially for such a long period of time,” said Reinhard Flick, a researcher at the Scripps Institution of Oceanography at UC San Diego. Water levels are at least “a half-foot above forecast for months.”
Without accounting for warm ocean temperatures, La Jolla would expect to see a maximum high tide of 6.14 feet Sunday morning, 6.44 feet Monday morning, 6.59 feet Tuesday morning, 6.55 feet Wednesday morning and 6.3 feet Thursday morning, according to federal government forecasts released years in advance. However, actual tides could push it past 8 feet.
Part of the problem is a long-predicted increase in high tides, caused by a particular alignment of the Earth, Moon and Sun. We are near the peaks of what are called the 18.6-year lunar node and 4.4-year lunar perigee tidal cycles, which result from small changes in the moon’s orbit and affect tide-generating forces, according to Flick.
Another problem is the record warm waters off the California coast, which are beginning to be influenced by the sending of warmer El Niño-fueled ocean waters from the Peruvian coast. Human-caused global warming also plays a role, with sea levels having risen about 30 centimeters over the past 125 years along the California coast.
Coastal flooding in the coming days is expected to be different from previous ones, heavily influenced by powerful swells caused by the remnants of Hurricanes Marie and Rachel. These swells influenced by tropical storms will not be present, but the tides will be higher this time.
Such conditions will particularly endanger areas that have already been engulfed by rising seawaters – such as the Long Beach Peninsula, where the ocean destroyed a historic boardwalk and destroyed homes; and Newport Beach’s Balboa Peninsula, which saw days of intense flooding.
“I think it will be on a similar scale,” said Philip Gonsalves, a meteorologist at the National Weather Service office in San Diego. “Different contributing factors will produce a similar result. »
Other areas that have been hit hard this year include Dana Point, where waves damaged beachfront homes, destroyed decks and tore up walls; and Malibu, where a sinkhole threatens actor Nicolas Cage’s home and the ocean has threatened to cut off road access to vehicles at Point Dume Beach, known by locals as Westward Beach.
In San Diego County, parts of Carlsbad State Beach were washed away, forcing the Tamarack day parking lot to be closed to vehicles. So much sand has eroded from popular Newport Beach surf spot The Wedge that the remnants of decades-old buried infrastructure, like rusty metal rods and chunks of concrete, have been exposed.
Areas that have already experienced beach erosion or infrastructure damage may be particularly vulnerable. Any additional flooding “exacerbates the problem because the damage is already there,” said Todd Hall, warning coordinating meteorologist with the weather service office in Oxnard.
One area of concern is Highway 1 in Ventura County near Point Mugu, where water has seeped under the road and weakened it, “making it more vulnerable to other tidal events,” Hall said. Crews are installing rocks to separate the causeway from the waves.
What is clear is that authorities and the public should not be surprised by this week’s coastal flooding.
“The warnings and advisories are real. People should take them seriously because conditions are favorable for flooding,” said Doug George, an oceanographer with the National Oceanic and Atmospheric Administration.
Newport Beach declared a local emergency ahead of the tides and activated its emergency operations center, preparing for flood prevention and response efforts. The city was also “reinforcing protective sand berms, preparing tide pumps and floodgates, and positioning resources in flood-prone areas,” officials said on social media.
The city said the highest tides it expects are 8.3 feet Monday at 9:15 a.m., 8.5 feet Tuesday at 9:50 a.m. and 8.4 feet Wednesday at 10:28 a.m. These adjusted numbers are 1.8 feet higher than forecasts that don’t take into account warmer ocean water.
Newport Beach and Long Beach are also rushing to move sand to shore up eroded beaches.
Newport Beach said about 30 to 40 trucks hauled sand from an area above Prado Dam to The Wedge, aiming to move 2,000 cubic yards by Saturday. Crews also installed thousands of sandbags in vulnerable areas of Balboa Island, the city said.
In response to a crack developing under the Coast Highway, or Highway 1, which runs from Newport Beach to Laguna Beach, the California Department of Transportation said it was placing 4-foot-high sand-filled barriers under the roadway near Crystal Cove. The two lanes closest to the cliff remain closed, with traffic directed to the remaining two lanes, one lane in each direction.
“The barriers will provide interim protection to the slope by helping to absorb wave energy. The next step will be to install an embankment buttress at the base of the slope, reinforced with large rocks to help reduce erosion and limit slope movement,” Caltrans said on social media.
Long Beach began dredging Alamitos Bay on Tuesday and is moving sand to the wave-battered peninsula beach, essentially using a giant pipe. The effort has “already added visible waterfront to the area adjacent to the 72nd Place parking lot” on the eastern edge of the peninsula, city spokeswoman Jen De Prez said. Repairs have also begun on the damaged Peninsula Parkway.
Metrolink announced it is suspending commuter rail service in southern Orange County and San Diego County for the upcoming work week, due to tidal forecasts.
In the Bay Area, crews closed a section of an entire state highway this weekend for 55 hours for emergency work to prepare for winter. The ultimate goal is to raise flood-prone portions of Highway 37, which connects Marin and Sonoma counties to Napa and Solano counties, by 3 feet.
El Niño is a climate phenomenon characterized by warmer waters in the central and eastern tropical Pacific Ocean, which cause changes in the atmosphere that can affect weather patterns around the world. El Niño events are typically associated with coastal erosion in California and stormier than usual weather conditions across the southern United States, including southern California.
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