El Niño Is Pretty Much Over for Southern California

El Niño Is Pretty Much Over for Southern California
File photo by Pacheco/Flickr

It was one of the strongest El Niños ever measured. It was supposed to bring us record rainfall. It was described by the Los Angeles Times as Godzilla.

It turned out to be a complete dud.

As Los Angeles faces several days of possible showers, starting with a system that's expected to move in tonight, it might not be the best time to declare that El Niño hasn't delivered.

But it hasn't.

"It's winding down," says state climatologist Michael Anderson. "We're moving outside our climatological window of significant precipitation for the water year."

What happened?

"For Southern California, this one missed," he said. "Heavy rain ended up farther north, all the way from the Bay Area to Washington State."

Indeed, the Bay Area has had near normal precipitation so far this winter, as opposed to years of drought, and the Pacific Northwest was inundated with way-above-average rainfall.

El Niño is the weather phenomenon by which equatorial Pacific waters are warmer than normal and can add significant moisture to a jet stream that usually aims for the West Coast of North America.

Similarly strong El Niños in the past, including those of 1983 and 1998, inundated Southern California with rain. The same was expected this winter.

Now "it's looking unlikely" that El Niño will deliver, at least for L.A., said Alan Haynes, a hydrologist for the National Weather Service in Sacramento.

"Experts are saying high pressure has been developing to the south of the West Coast of North America, which prevented the jet stream from coming down south as much as it can," explained Jin-Yi Yu, an earth system science professor at UC Irvine. "I don't think people have explained why we have this high pressure over the southern part of the West Coast."

The high helped us achieve one of the warmest Februaries ever recorded. It also ensured that downtown Los Angeles received about half of normal rainfall. Even more conservative federal forecasters called for a 60 percent chance of above-normal precipitation in Southern California this winter.

Yi has a theory about what might have happened. He says that El Niño behaved normally from summer to December, when it was focused on the eastern Pacific. 

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But as the new year arrived, the warmest waters shifted to the central Pacific. That correlated with the jet stream moving northward. And it's an aspect of the phenomenon that's different from what we saw in '83 and '98.

While most experts say that this El Niño is rapidly decaying and could switch to La Niña conditions, represented by colder-than-normal equatorial Pacific waters and a drier-than-normal winter for California, Yi thinks the abnormal behavior of this El Niño could have different results.

"I expect this El Niño to weaken, but the equatorial water will still be warmer than normal until this summer, " he said. "It probably won't change back to La Niña this summer."

That won't have huge impacts on our summer weather, which some forecasters expect to see higher-than-normal temps, but it's interesting nonetheless.

As far as why the jet stream skipped us this winter, "Scientists will be studying [that] for the next couple years," says National Weather Service meteorologist Joe Sirard.

In the meantime, we could get serious rain. In April.

Could El Niño just be striking way late in the game? It's not impossible.

Sirard notes that the El Niño of '83 helped to produce a whopping 5.16 inches in April of that year. If we got that much precipitation this month, we'd still be slightly below rainfall for even a normal season, however.

"April can be unpredictable," he said. "There is the potential for a couple inches between now and next Wednesday."

Following Thursday's rain, showers were possible over the weekend and then again in the middle of next week, forecasters said. The NWS said thunderstorms were possible Friday and Saturday. 

It's hard to say if El Niño was influencing this series of fronts, experts said. But it seems likely, especially with a warm storm moving in tonight that's drawing moisture from the south.

"It probably is adding something to the strength of the system," said Haynes of the NWS in Sacramento.

But it's probably too little too late.


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