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6 Common Misconceptions About El Niño and Its Impact on California Weather

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A large wave crashes onto seaside houses.
El Niño-generated storm waves crash onto seaside houses at Mondos Beach on Jan. 12, 2016. (Mark Ralston/AFP/Getty Images)

After a four-year hiatus, El Niño is widely expected to make a grand reentrance this summer, ushering in the possibility of yet another wet, stormy winter.

“It looks like it’s full steam ahead,” UCLA climate scientist Daniel Swain said in a live YouTube interview last week, in which he placed the likelihood of a strong El Niño event at greater than 50% — even as projections still vary widely.

“A strong event does have the potential for strong impacts on California,” said Swain.

The El Niño climate phenomenon — the opposite of La Niña — generally occurs every three to five years when ocean waters along the equator in the eastern Pacific warm by at least a half-degree Fahrenheit.

A vertical bar chart showing El Niño events since 1950.

That, in turn, can reposition the jet stream and funnel storms toward the West Coast, often resulting in increased rainfall across thousands of miles, said John Monteverdi, emeritus professor of meteorology at San Francisco State University.

But a wet winter is not at all guaranteed, he said, noting that only one out of about six current models predicts a strong El Niño as this year progresses.

“People have been sort of charmed into believing that all El Niños mean storms,” Monteverdi said. “The historical record does not support a sure bet on that.”

Misconceptions about this mysterious weather pattern abound. Below are six of the most common ones.

Misconception 1: El Niño comes to California

Every time Jan Null reads a headline saying El Niño is coming to the West Coast, he cringes. The local forecaster, who founded Golden Gate Weather Service, said the headlines aren’t factual because El Niño actually occurs “about 3,000 miles away from California. It does not move en masse toward the California coast.” It can, however, greatly affect the weather in California.

Misconception 2: Every El Niño event and its effects are identical

For the more than seven decades that El Niños have been tracked, their strength and impact have varied significantly, with many having little impact in California.

“The general notion is that El Niño brings wetter winters in California, although the relationship is somewhat fragile,” said UC Berkeley climate scientist John Chiang. “It’s really only the strong El Niños that affect rainfall over Northern California.”

And a slew of other oceanic and atmospheric variables can enhance or diffuse the effects of El Niño, noted meteorologist Null, saying, “I’ve often referred to it as the alphabet soup of all these other climate things going on.”

Misconception 3: El Niño is a storm

“El Niño is not a storm in and of itself,” Monteverdi said.

Rather, he explains, it is a phenomenon that can prime the atmosphere to push more robust storms toward the West Coast.

El Niños do “not spawn storms” and “do not directly create storms over California or anywhere else,” added Null.

Misconception 4: El Niños always result in catastrophic flooding

Significant flooding can just as likely occur in a non-El Niño period like the one Californians experienced this past winter (which was technically in a La Niña year).

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Since 1950, there have been 26 El Niño years, and that doesn’t include some of the costliest flood years, Null said. That means it’s very difficult to accurately predict just how wet a winter we’re in for this year, he said.

“It’s slightly skewed toward the wetter than normal, but it’s not something where I’d reach into my wallet and put money on the table betting on it,” he said.

Misconception 5: El Niños cause elevated ocean temperatures along California’s coastal waters

El Niño is not responsible for any warming of ocean temperatures along the California coast.

“It’s not true that when we have El Niño, we automatically have warm water immediately west of San Francisco,” said Monteverdi. “It refers to an oceanographic phenomenon in the tropical Pacific well away from us.”

The water along California is primarily influenced by the California Current, which runs from north to south from the Gulf of Alaska down along the West Coast, where cold water comes to the surface.

“There’s no real transport mechanism for the warm water at the equator 3,000 miles away to get to the California coast and that sort of gets lost in the discussion,” said Null.

Misconception 6: Climate change is having a clear impact on the frequency and severity of El Niños

While climate change from the burning of fossil fuels has indisputably accelerated weather extremes in California — fueling significantly wetter and dryer conditions — climate experts still don’t know precisely how it has affected the nature of El Niño, in part because records about it in California only go back to about 1950.

“If we have this conversation 20 years from now, we may start seeing more of these big events in that same time frame — then it’s easier to attribute it [to climate change],” Null said. “Right now, they’re still separating the signal from the noise.”

Even so, future storms fueled by El Niños could be a whole lot wetter than they used to be because of climate change, which has resulted in an increasingly warmer atmosphere that can hold more water and, in turn, dump more on land.

Global ocean warming “will change our weather patterns,” said Chiang, of UC Berkeley. “It’ll change the impact of El Niño. So, whether we see it now or in the decades ahead, that’s still an open debate.”

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