October 4, 2023

Phil Diehl | The San Diego Union-Tribune

San Diego County’s fragile shoreline and weak beachfront properties could possibly be in for a tough winter, in keeping with the California Coastal Fee, the Nationwide Climate Service and a few prime San Diego scientists.

“We’re an rising El Niño occasion,” employees geologist Joseph Avenue advised the Coastal Fee at its assembly Wednesday in Eureka.

An El Niño is a meteorological phenomenon that happens each two to seven years. The water temperature on the floor of the Central Pacific Ocean alongside the equator warms a number of levels above its long-term common, creating circumstances for stronger, extra frequent seasonal storms throughout a lot of the globe.

“El Niño circumstances can generate a triple menace for coastal hazards in California,” mentioned Adam Younger, an integrative oceanography researcher at Scripps Establishment of Oceanography in San Diego.

“Elevated rainfall triggers landslides, highly effective waves can speed up erosion of seashores, sea cliffs, and bluffs, and trigger coastal flooding, and powerful El Niño circumstances can increase sea degree on the California coast by 6 to 13 inches,” Younger mentioned. “Mixed, these components improve coastal erosion and flooding … which might threaten public parks, seashores, vital infrastructure, highways, and houses.”

The Coastal Fee’s webpage at www.coastal.ca.gov has been up to date with El Niño data and sources, and staffers are working to publicize the scenario.

“We’re sort of elevating the flag on this,” mentioned fee Chair Donne Brownsey.

“Each single day there’s a new report in regards to the warming ocean, the rising seas, and the accelerated melting of the arctic,” Brownsey mentioned. “It simply goes on and on. It is a harbinger that’s actually scary.”

Highly effective storms could be “a formulation for catastrophe” in coastal communities already topic to seasonal flooding, mentioned Imperial Seaside Mayor Paloma Aguirre, who represents San Diego County on the Coastal Fee.

“We see it first-hand in Imperial Seaside,” Aguirre mentioned. “We simply had the first-ever tropical storm make landfall in San Diego County. It’s extraordinarily regarding to say the least.”

Tropical Storm Hilary dropped greater than 2 inches of rain on most components of San Diego County in August, and as a lot as 7 inches on the highest elevations. August is generally one in every of San Diego’s driest months of the 12 months, with a mean precipitation of about one-third inch alongside the coast.

There’s a 95 p.c probability of an El Niño occurring between December 2023 and February 2024, and a 66 p.c that will probably be a “robust” El Niño, in keeping with an replace issued Tuesday by the Nationwide Climate Service. Indicators embrace above common sea floor temperatures and “atmospheric anomalies” within the Pacific.

Nonetheless, predicting the climate is notoriously tough.

El Niño circumstances don’t trigger particular person storms, moderately they affect the frequency and traits of storms.

“El Niño alone will not be a dependable bellwether for a significant storm season,” mentioned Avenue, the fee’s geologist. “We’ve had a number of fizzles.”

Many variations can take form for an El Niño, and solely time will inform if this winter brings a whopper.

Two of Southern California’s strongest El Niños occurred within the winters of 1982-83 and 1997-98, bringing intensive flooding, landslides, coastal erosion and injury to coastal constructions. Statewide storm-related injury in ’97-98 was estimated at greater than $1 billion, in keeping with the Climate Service.

In January 1993, thought-about one of many milder El Nino years, Camp Pendleton Marine Corps base shut down after 11 consecutive days of rain to cope with water 15 ft deep on the air station and components of Vandegrift Boulevard. A Marine normal estimated the injury to property and navy tools at $70 million.

El Niño circumstances final occurred in Southern California in 2015-16 and introduced highly effective waves and coastal erosion. However there was much less rainfall than anticipated and little structural injury just because the jet stream carried a lot of the storms to the north.

A 12 months in the past, the winter of 2022-23 was unusually moist with highly effective storms and a few of the greatest ocean waves the world has ever seen. Nonetheless, that season didn’t have the ocean temperatures and atmospheric circumstances of an El Niño.

Rail service in Southern California is especially weak to the landslides and bluff failures introduced by winter storms.

Climate-related landslides at two coastal hassle spots in San Clemente pressured the suspension of passenger service for months at a time over the previous two years. The tracks alongside the coast by way of Orange County are the one hyperlink between San Diego and Los Angeles for rail passengers and freight.

Emergency bluff repairs in 2021 price greater than $10 million at Del Mar, the place a sequence of railroad stabilization tasks have been underway for greater than 20 years.

Any sequence of robust storms may cause a short lived rise in sea degree that will increase flooding and erosion, mentioned Jeremy Smith, an engineer on the Coastal Fee employees. That occurred in 2016, when ocean waters rose as a lot as 8 inches alongside some components of the California coast.

“Sturdy storms in fast succession could be damaging,” Smith mentioned. “The worst injury happens when giant swells mix with excessive tides.”

The best tides of the 12 months, generally known as “king tides,” happen on a number of days in mid-summer and mid-winter. This winter’s king tides will probably be Jan. 11 and 12 and Feb. 9 and 10, 2024.

“Widespread coastal injury that occurred through the winter of 1982-83 was due partly to the mix of huge storm waves with very excessive tides,” states a fee employees report.

“A number of the highest tides for the 2023-24 winter will happen near holidays,” it states. “This highlights the necessity for early preparation since holidays are instances that folks are likely to journey and go on trip.”

Preparation consists of cleansing out gutters, storm drains and flood management basins, inspecting roofs for leaks, and planting floor cowl on naked spots.