CALIFORNIA — As months of headlines trumpeting an historic El Niño winter gave way to a lackluster start to California’s rainy season, something unprecedented was quietly happening in the Pacific Ocean.
Historically warm surface temperatures contributed to an increased likelihood of an El Niño for the record books, according to the National Oceanic and Atmospheric Administration’s Climate Prediction Center.
“Based on the latest forecasts, there is now a 54% chance of a “historically strong” El Niño during the November-January season,” according to the Climate Prediction Center. “An event of this strength would potentially be in the top 5 of El Niño events since 1950.”
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As if on cue, a series of storms are expected to bring heavy rain to northern California this week with a pair of storms bringing moderate rain to Southern California.
Since October, California has seen a drier-than-normal fall and winter. However, there are signs emerging that the rainy season is kicking into gear.
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With El Niño, the jet stream tends to shift atmospheric rivers southeast squarely over Southern California.
“The models have been relatively consistent with developing a good strong jet from Asia out to the date line, and then it’s forecast to gradually progress on toward the West Coast,” said Jan Null, an adjunct professor of meteorology at San José State University told The Washington Post.
A strong El Niño is associated with increased rain and warmer winter temperatures throughout much of California, but the Climate Prediction Center reiterated a caveat about the unpredictability of the weather phenomenon.
“While stronger El Niño events increase the likelihood of El Niño-related climate anomalies, it does not imply expected impacts will emerge in all locations or be of strong intensity,” the Climate Prediction Center explained in its Dec. 14 El Niño advisory.
While scientists anticipate a rare super El Niño over the winter, there are signs it will abruptly return to neutral conditions by summer.
National Oceanic and Atmospheric models show a likely end to El Niño conditions by June and a return to neutral conditions. And then, well La Niña, which brings drier than normal weather conditions is a good bet. Just this year California emerged from a three-year repeat of La Niña coinciding with extreme drought in California.
“What goes up must come down! Our current thinking is that neutral conditions are most likely to develop by April–June,” the Climate Prediction Center wrote on its ENSO blog. “Then…La Niña and neutral are nearly even odds for July–September, with El Niño a distant third. Most, but not all, of the stronger El Niño events in our historical record were followed by La Niña, so that would not be unusual.”
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