The strongest El Nino in 140 years? It can actually deliver for California

A rare cluster of three tropical cyclones will sweep across the western Pacific on both sides of the equator this week, creating what one scientist calls potentially the strongest westerly winds in the equatorial Pacific in recent centuries. The eruption is pushing warm water eastward at a critical moment, intensifying what University at Albany atmospheric scientist Paul Roundy called “the real possibility of the strongest El Niño event in 140 years.”

The European Center for Medium-Range Weather Forecasts for its recently released April weather forecast shows that all of its models expect the world to reach El Niño conditions by mid-June. About half project sea surface temperatures to be 2.5 degrees Celsius above average by October.

A strong El Niño will likely significantly reshape global weather patterns, potentially pushing global temperatures to record levels in 2027.

Tropical cyclones are the latest evidence of an emerging, potentially record El Niño. Their combined circulation is fueling the outbreak of westerly winds that are now pushing the warm waters eastward in the Pacific Ocean. That burst “is located to the west of the current warmest water in the Pacific Ocean, so it’s ideally placed to drive that warm water eastward to create a strong El Niño event,” Roundy said. He estimated that the setup could lead to El Niño coming sooner, within one to two months.

It is the latest in a series of powerful westerly winds that have swept across the equatorial Pacific since January, ending a La Niña pattern that has spread unusually warm waters both at the surface and deep into the Pacific Ocean. Each successive eruption pushed that warm water further east, and this rare triple cyclonic pattern, fueled by it, could be the strongest yet.

“What’s different this year is the level of agreement in many models, not just one,” said Muhammad Azhar Ehsan, a climate scientist at Columbia University’s International Research Institute for Climate and Society. Except for Europe, forecasters from Australia and NASA “are all pointing to a strong El Nino,” he said. The next official forecast from his research institute, due April 19, is expected to be stronger than last month’s outlook, Ehsan said.

The National Oceanic and Atmospheric Administration is scheduled to release its updated estimates on El Niño on Thursday.

While El Nino is expected to bring more rain to California, residents have reason to take the news with a dose of uncertainty. In 2015, forecasters warned that a “Godzilla El Niño” would emerge, ending a devastating multi-year drought that has depleted reservoirs and left communities on water rations. A strong El Niño arrived, but no drought-breaking rains. The Bay Area finished the winter with near-average precipitation, while Southern California actually came in at just 72 percent below normal. It was a reminder that not all El Niño events play out as expected.

1997 parallel

Roundy said the developing phenomenon is “really following the evolution of 1997,” when warming originated in the eastern tropical Pacific near the South American coast. That’s a pattern associated with strong El Niño events that translate to above-normal rainfall in California. During the El Niño years of 1982-83, hurricanes destroyed 33 oceanfront homes, damaged thousands and caused millions in damage in 46 disaster-declared counties. The 1997-98 El Niño winter brought double-than-normal rainfall to much of the state, causing 17 storm-related deaths and nearly $850 million in damage.

The 2015-16 event, in contrast, developed for the first time in the central Pacific, as Roundy described, “favoring heavy rainfall over the California coast rather than California.”

Daniel Kean, a climate researcher at the Scripps Institution of Oceanography who has studied California’s hydropower for decades, said he sees reason for cautious optimism about water resources in California and the western U.S. next year.

“I’m excited about a strong El Nino,” Kayan said. “It looks promising as a pretty strong event that will probably continue through the winter of 26-27.”

If the eastern tropical Pacific stays warm through the winter, Cayan said, California will often see a storm track pattern that leads Pacific storms directly into the state.

“Hopefully that means the Southwest, which has been extremely dry, will enjoy some renewed moisture, Keyan said. However, he added, ‘It’s still early.’

Kayan eyed his approach carefully. “It’s all about being careful from injuries and beatings from previous (experiences),” he said.

Roundy struck a similar note. “I can’t rule out the possibility that the (sea surface temperature) pattern in California’s wet season will be similar to 2015,” he said, while the program started more like 1997 than 2015.

One sign to watch for is summer and fall temperatures. Cayan noted that in previous strong eastern Pacific El Niño events, temperatures in the West were actually cooler than summer-to-winter averages. If that pattern starts to emerge this summer, it could be a sign that the event may be tracking the 1997 playbook.

But Cayan cautioned that each event has its own characteristics, and today’s much warmer ocean baseline means historical patterns may not neatly repeat themselves.

By mid-summer, the picture should be pretty clear. For now, the ingredients are in place for the historic event.

This article was originally published The strongest El Nino in 140 years? It can actually deliver for California.