A powerful El Niño has officially reached "super" strength this week, and, as if on cue, three-story waves prompted evacuation warnings along Northern California's coast. Record sea levels set earlier this month are likely to be shattered again before month's end, and the first of three back-to-back storms doused the state from north to south.
The National Oceanic and Atmospheric Administration's Climate Prediction Center said Thursday that El Niño strengthened in October and is expected to intensify even further through early 2027. Forecasters put the chances of it becoming the strongest event since 1950 at about 60% during the October-December and November-January periods.
There is also a greater than 79% chance of strong to very strong El Niño conditions continuing January through March, according to the latest federal outlook.
"This is not your normal El Niño," Daniel Rudnick, a physical oceanographer at UC San Diego's Scripps Institution of Oceanography, told SFGATE. "This is really big."
SEE ALSO: Monster Waves Up To 50 Feet Threaten Bay Area Coast As Storms Arrive
The climate pattern has reached the very strong category, commonly called a "super" El Niño, only six times since 1950, including the current event, according to AccuWeather. Previous events include the winters of 1997-98 and 2015-16.
AccuWeather forecasters expect more atmospheric rivers to hit the West Coast this winter, potentially bringing flooding, landslides and significant mountain snowfall.
Some effects are already being felt in California.
SEE ALSO: Sheriff Urges Evacuation As 3-Story Waves Take Aim At Santa Cruz Coast
Ocean levels reached record highs in San Diego, La Jolla, Los Angeles and Santa Barbara in late October, according to a Nov. 4 NOAA report.
Between Oct. 24 and 30, water levels rose 2.80 feet above the average daily high tide in San Diego, 2.65 feet in La Jolla, 2.70 feet in Los Angeles and 2.65 feet in Santa Barbara. All four locations recorded their highest water levels on record.
Santa Monica recorded its second-highest water level, while Port San Luis and Monterey also ranked among their highest readings.
NOAA attributed the extreme water levels to a combination of unusually high tides, warm ocean temperatures and large waves of warm water generated by El Niño. El Niño-driven Kelvin waves can temporarily raise sea levels by 6 to 12 inches or more along the West Coast.
"It's clearly beginning to impact California," Alexander Gershunov, a research meteorologist for Scripps, told SFGATE. "Sea levels are anywhere between a foot and a foot-and-half higher than predicted, and most of that is due to the Kelvin waves generated by El Niño."
And more unusually high tides are approaching.
NOAA predicts elevated tides Nov. 22-27 and Dec. 22-26, increasing the risk of additional coastal flooding.
More warm-water waves or Kelvin waves are also likely throughout fall and winter, potentially keeping ocean levels elevated.
Heavy rainfall and runoff from winter storms could worsen coastal flooding in areas where water levels are already elevated, according to NOAA.
El Niño's typical winter weather patterns may already be emerging one to two months earlier than usual, according to meteorologist Eric Webb, whose findings were cited by The Weather Channel.
Albuquerque, New Mexico; Flagstaff, Arizona; and West Palm Beach, Florida, experienced their wettest fall on record through Nov. 4, while Chicago, Dallas, Houston and Nashville were among dozens of central U.S. cities experiencing record warmth.
El Niño develops when waters in the central and eastern tropical Pacific become unusually warm, influencing weather patterns around the world. Strong El Niño events typically increase the likelihood of wetter-than-average winters across Southern California and the Southwest, although increased rainfall is not guaranteed.
The latest NOAA data showed ocean temperatures in a key region of the tropical Pacific reached 2.5 degrees Celsius above normal in October, up from 2.1 degrees in September.
Michelle L'Heureux, a physical scientist with NOAA's Climate Prediction Center, told SFGATE that whether El Niño ultimately breaks a historical record matters less than the weather impacts it could bring to North America.
"This is a significant El Nino event already, it is expected to remain significant, and we should prepare for a likely influence on North America," she said.
Climate scientist Daniel Swain of the University of California's Agriculture and Natural Resources division also cautioned during a recent livestream that a dry fall would not rule out a wet winter, particularly beginning in mid-December or January, according to SFGATE.
For now, California's coastal communities face a more immediate concern: 50-foot waves along Northern California's coast triggered evacuation warnings in Santa Cruz Friday and create the risk of deadly sneaker waves, and coastal erosion and flooding.
NOAA advises residents to monitor its Monthly High Tide Flooding Outlook and check the National Weather Service for local coastal flood warnings and advisories.
More California News:
Sign up for free local newsletters and alerts for the
Across California Patch
Patch.com is the nationwide leader in hyperlocal news.
Visit Patch.com to find your town today.