A season of record-breaking tropical storms and hurricanes in the Pacific Ocean is battering the southern California coast.
Colorado State University researchers confirmed Monday that this summer’s storms generated a higher level of accumulated cyclone energy than ever recorded, surpassing the previous seasonal record set in 2018. The metric is a measure of the total wind energy, intensity and duration of tropical storms and hurricanes.
“It’s been a wild season,” said Daniel Cayan, a climate researcher at the Scripps Institution of Oceanography at UC San Diego, noting that parts of the Southern California coast have already suffered significant damage ahead of winter storms that could batter the region amid the strongest El Niño on record.
Long Beach’s historic boardwalk has buckled after a barrage of storms over the past month. As Tropical Storm Rachel approached the coast this weekend, powerful waves crashed into beachfront homes, leaving some on the brink of collapse.
In Newport Beach, water from a massive swell – twice as large as originally predicted – broke through 20-foot berms erected on the beach and flooded roads with about a foot of seawater before Rachel arrived.
Elsewhere along the coast, continued pounding from higher-than-normal ocean levels and strong waves this summer have washed away sand, profoundly altering the Newport Beach Wedge, as well as the beaches of San Onofre, Laguna Beach and San Clemente. The coastal damage was so severe that Orange County declared a state of emergency last month.
The unusually active hurricane season in the Pacific is influenced by several factors, including a long-term trend of ocean warming caused by global warming, higher ocean temperatures near coasts, and decreased wind shear from El Niño, which can significantly weaken hurricane activity, UC Agriculture and Natural Resources climatologist Daniel Swain explained during a recent webinar.
“El Niño in the Pacific basin decreases wind shear, which removes the storm-inhibiting and decapitating effect of wind shear while amplifying water temperatures,” Swain said. “So it adds more fuel and makes that fuel more likely to take advantage of its environment.”
Typically, once storms enter the colder waters of the eastern tropical Pacific, they weaken significantly. But the marine heatwave and El Niño conditions — which brought ocean temperatures 10 to 13 degrees above normal — created a more conducive environment for hurricanes such as Rachel, which came close enough to impact the California coast.
These storms, combined with high tides and the Kelvin wave, which can add 6 to 12 inches to sea level, resulted in significant damage and reshaping of the coastline over the summer.
And it’s not over yet, experts say.
Hurricane Simon, currently barreling across Mexico’s west coast, is expected to make landfall there this week, and forecasters estimate there is about a 90 percent chance another cyclone will form within the next seven days.
“I wouldn’t be surprised if we see a few more hurricanes or tropical systems forming in the Central and South Pacific region,” said Kristan Lund, a meteorologist with the National Weather Service in Oxnard.
Southern California is also preparing to see what El Niño has in store for us this winter.
The National Oceanic and Atmospheric Administration’s Climate Prediction Center said last week that there is virtually a 100 percent chance that this season’s El Niño will be classified as “very strong.” There is also an 83% chance that this El Niño will be the strongest on record, dating back to 1950, compared to a 75% chance predicted last month.
Even if it does not bring torrential rains, El Niño can wreak havoc on the coast.
Beaches typically go through a seasonal cycle with powerful winter waves carrying sand out to sea and gentler summer waves depositing sand on the shore. But El Niño winters typically bring even stronger waves, leading to more sand loss and erosion.
“There will probably be some pretty deep influences along the coast,” Cayan said of the coming months. “There (are) also cliff breaks and other impacts when you get these big waves that are higher and more active than normal, so there’s a lot of concern about that.”
Two of the strongest El Niño events in the past 75 years, in 1982-83 and 1997-98, were associated with extensive damage on the southern California coast, with homes destroyed, streets flooded and docks damaged.
Another episode – in 2015-2016 – did not result in above-average rainfall, but caused record coastal erosion. During this winter, researchers determined that the most extreme waves were about 50% larger than usual and the level of beach erosion was 76% higher than normal.
“Since that really bad winter of 1983, we’ve had quite active winter storms several times, but we’ve kind of dodged the bullets because those storms, generally speaking, didn’t fall on the highest tides,” Cayan said. “So this winter, again, it’s going to be kind of a draw.”
This winter, if El Niño-fueled storms arrive during high tides, it’s likely that California will experience significant coastal erosion, flooding and damage, Cayan said. King tides, which can push water levels past 7 feet, or more during El Niño, are expected around Thanksgiving, Christmas and late January.
“These times are really critical to the fate of California’s coastline and infrastructure this winter,” Cayan said.
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