The vision of El Nino as producer of historic California storms may be outdated
S E E D E D C O N T E N T
SAN DIEGO — In 1983, El Nino brought historic flooding to parts of Southern California, toppling sections of fishing piers and inspiring some to travel submerged streets by surfboard. In 1998, it returned, dusting regional mountains with snow through May.
For Californians' collective mind, the weather phenomenon, defined by an eastward-moving, warmer-than-normal sea surface along the equatorial Pacific, is shaped by those traumatic, potent winters with record precipitation.
But as some earth scientists see a bit of 1983 or 1998 in the coming winter's strong El Nino, they may be neglecting a new reality: A stormy, wet El Nino of that vintage hasn't struck California this century.
University of California, Irvine, earth system science professor Jin-Yi Yu, whose doubts about a predicted "Godzilla El Nino" in 2015-16 were confirmed, sees the phenomenon permanently changed.
"El Ninos in these respective centuries are distinct," Yu said in a series of emails. "Recent El Nino and La Nina events have behaved differently from what we initially expected."
While Yu is once again a rare voice discounting the chances of a wet El Nino for California this winter, many of the state's most influential weather watchers are not wholly opposed to his bearish outlook.
The National Oceanic and Atmospheric Administration said the current El Nino is "strong" by its measurements, which could translate into strong storms affecting parts of the state.
State Climatologist Michael Anderson, who also expressed some doubt in 2015's "Godzilla El Nino" predictions, has called on Californians to essentially be ready for anything.
"Until better seasonal forecasts are available, California is preparing for both extreme wet or extreme dry conditions," he said by email.
That may be wise in a weather world that sometimes seems upside down.
Though the 2022-23 season was designated as a La Nina year —usually drier and cooler — the state received 141% of average precipitation for the water year that ended Sept. 30, the California Department of Water Resources said. The snowpack in the Sierra Nevada mountains rivaled that of 1983, it said.
Landslide damage in La Canada Flintridge, Calif., on Feb. 27.Allen J. Schaben / Los Angeles Times via Getty Images file
How accurate are El Nino predictions?
Tim Barnett, the late marine geophysicist at the University of California, San Diego's Scripps Institution of Oceanography, predicted the strong, stormy El Nino winter of 1997-98, a quantum leap for a meteorology world that is still 50-50 with 10-day forecasts.
It was the first, last and only time a stormy El Nino for California has successfully been forecast. Storms that season caused $850 million in damage in the state and doubled its normal precipitation, according to meteorologist Jan Null's Golden Gate Weather Services.
Null, a retired lead forecaster for the National Weather Service's San Francisco Bay Area office, said there have been 26 El Ninos and 25 La Ninas since 1950, the vast majority of the former failing to act like those of 1982-83 or 1997-98.
"El Nino is the Stephen Curry superstar of the game," Null said, referring to the Golden State Warriors' point guard. "But sometimes someone else has a good night and has a bigger influence."
Last winter's wet La Nina, he said, "totally flipped the script."
What are the chances of a rainy winter?
Anderson, the state climatologist, said an even number of El Ninos this century have produced dry and wet winters. "El Nino by itself does not always translate into wet conditions," he said.
The Scripps Institution's Center for Western Weather and Water Extremes puts the chances of a wetter-than-normal winter for most of California at essentially 50-50, though its basis is historical data, not long-range forecasts.
A NOAA long-range forecast map from October shows equal chances for above- or below-average rainfall this winter for the southernmost coast of California, with the chances "leaning" in favor of greater-than-normal rain for the rest of Southern California and extending to the Bay Area.
The state Department of Water Resources said last month that residents should prepare for "the possibility of another wet season under strong El Nino conditions."
Shang-Ping Xie, a climate sciences researcher at the Scripps Institution, puts the chances of a rainy El Nino in California this winter at 2-to-1.
"We had a three-year La Nina," he said. "Two were dry and one was wet. The odds are not that different from typical results, which say La Nina favors a dry winter."
But in the two classic examples of stormy El Nino winters for California, the month of March bore the brunt of rain, wind and damage.
"March is the time we believe the tropical ocean is most influential on North America," Xie said.
Are other factors affecting the forecast?
While its behavior can be unpredictable, identifying El Nino is relatively basic, reliant on a massive patch of water in the equatorial Pacific that, when found to be consistently warmer than average, triggers declaration of the phenomenon, normally for winter.
El Nino's relative warmth can affect atmospheric circulation along the equator and nudge a jet stream that normally aims for the Pacific Northwest southward, leaving that region drier and the Southeast wetter.
El Nino's no-show in 2015-16 prompted Yu of UC Irvine to dive into possible causes, and today he believes other weather and manmade phenomena are affecting it.
He thinks global warming, in part, and possibly deforestation in Southeast Asia may have helped to create a second warm patch of water adjacent to El Nino's that may be thwarting its old ways.
El Ninos this century have "shifted westward to the central Pacific and lasted longer, becoming multi-year events," Yu said. "El Nino has changed."
People swim in the Pacific Ocean off Del Mar beach in La Jolla, Calif., in 2015.Brendan Smialowski / AFP via Getty Images file
Xie, the Scripps researcher who believes the odds favor a stormy El Nino, nevertheless believes there are influences on the phenomenon triggered by climate change. For example, he said, the ocean around the surface warming that defines El Nino is also warming on a long-term basis.
What happens when that warmth becomes the new baseline for a wider swath of ocean?
"If that pattern is holding up in the future, then the El Nino influence is going to strengthen," Xie said.
He believes El Nino data and computer modeling may not be keeping up.
"There are a lot of questions we still need to answer," he said.
Null said all eyes are on academia to help sort out what becomes of El Nino, particularly for the country's most populous state, normally in its path.
"It's a continual learning game," he said. "We have evolved in our understanding of El Nino but then complicated it by the atmosphere and the oceans getting warmer."
"Are we keeping up?" he asked. "I don't know."
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The stormy season on the West Coast is just getting started. We'll see how the actual weather produced by these more favorable conditions pans out.