Photo: Eric from Berkeley, CC BY 2.0, via Wikimedia Commons
The National Weather Service has issued a coastal flood warning for the Orange and San Diego county coasts, in effect from 5 a.m. on Sunday, October 25, until 1 p.m. on Thursday, October 29, as a round of king tides — amplified by unusually warm ocean water — threatens to flood low-lying neighborhoods, roads, beach parking lots and walkways along the Southern California coast. Coastal flood advisories are also in effect for the beaches of Los Angeles and Ventura counties.
King tides occur when the sun, moon and Earth align and the moon is near its closest point to Earth, producing the highest tides of the year. They can be predicted months in advance. What forecasters cannot predict as precisely is how much extra water a warm, swollen ocean will pile on top of them — and that is what has made this round dangerous. In Newport Beach, Sunday morning's astronomical high tide alone was about 6.2 feet, and the Weather Service expected ocean levels to run roughly one to 1.7 feet above prediction as the week began, with elevated surf adding to the risk along exposed beaches.
Newport Beach braces for the highest water
Officials in Newport Beach say actual water levels are already running 18 to 22 inches higher than astronomical predictions, pushed up by an El Niño-related Kelvin wave travelling along the coast. The city has declared a local emergency, activated its emergency operations center and deployed sandbags, protective berms and pumps, and it plans to move roughly 100,000 cubic yards of sand back onto eroded beaches. Its adjusted forecasts call for tides peaking at about 8.3 feet on Monday morning, 8.5 feet on Tuesday and 8.4 feet on Wednesday, with the worst flooding expected around the morning high tides.
Residents of low-lying neighborhoods spent the weekend stacking sandbags and clearing ground floors. "I've lived here 30 years, and I've never seen anything like this," said Newport Beach resident Laura Hamilton, who watched water run down her street when flooding covered parts of the Balboa Peninsula earlier this month. "Everything… sandbags upon sandbags, just trying to make sure everything is cleared off my floor," she said.
A coastline already battered
The warning lands on a shoreline with little left to spare. Weeks of hurricane-generated swells — from Marie, Polo and Rachel — have stripped sand from beaches up and down the coast and fractured a 360-foot bluff beneath Pacific Coast Highway near El Morro in Crystal Cove State Park, where crews are mounting a $4 million emergency effort to shore up the cliff with heavy equipment, rocks and sand-filled bags.
In Capistrano Beach, seven homes along Beach Road have been red-tagged as uninhabitable after suffering structural damage, and two have already been demolished. On the Long Beach Peninsula, eight buildings covering 13 residential addresses have been red-tagged, with residents demanding more permanent protection as the new tides approach.
Forecasters say total water levels could run as much as a foot and a half above predicted tides through the week, flooding buildings close to sea level along the Orange County coast and pushing water inland across vulnerable stretches of coastline. The highest tides are expected during the mornings from Monday through Wednesday, peaking on Tuesday, but the warning remains in place into Thursday afternoon while the elevated water lingers. The Weather Service urged people along the coast to stay vigilant, be prepared and take whatever measures they can to protect life and property until the water recedes.
Sources: National Weather Service, New York Post, FOX 11 Los Angeles