El Niño Forecast Reaches ‘Very Strong’ Category

A "very strong" El Niño could be good for California, which is in its fourth year of drought

Chances continue to increase that Southern California will get major drought relief this winter from storms associated with powerful El Niño conditions, according to climate scientists and a new analysis from the federal Climate Predication Center.

The most recent forecasts show El Niño reaching the "very strong" category, and likely to persist through the winter months when the most rain and snow is likely to fall. The odds of El Niño continuing through winter are now put at 90 percent, with an 85 percent likelihood it will continue until early spring.

"It definitely looks like the real deal," said Bill Patzert, a climatologist at NASA's Jet Propulsion Laboratory. "This is the Godzilla El Niño if it matures and comes to actual fruition."

Strong El Niño conditions are associated with wetter winters in Southern California and across the southern tier of the United States, while other areas in the states, Central America, and the western Pacific receive less precipitation.   

Data-gathering satellites have been monitoring the development of El Niñ, the term given the phenomenon in which tropical waters in the Pacific Ocean become warmer than typical near the Americas, and cooler in the western Pacific.

A larger change in temperature means a stronger El Niño. A weak El Niño has minimal impact, as last winter when drought-stricken California received below average precipitation for a fourth straight year.

The term was first applied by Spanish speakers in the Americas near the equator, where the phenomenon arrives near Christmastime. "El Niño" refers to the Christ child.

In this year's data, Patzert sees a pattern remarkably similar to the growth of the last major El Niño in 1997-98.

"Right now the signal we see, from the satellite, is larger than August of 1997," Patzert said. "This could be the El Niño of our generation."

Its moisture being seen as a potential rescuer during drought represents a role reversal for El Niño, which was blamed for billions of dollars in storm damage in 1997-98 and previously in 1982-83, when piers were torn apart by massive waves and storm surges, and floods and mudslides poured from hills.

"El Niño is definitely a double-bladed sword," Patzert said.

Some "preliminary impact" is already being felt, he said. Patzert is reluctant to ascribe specific meteorological events to the direct influence of El Niño. But he said the monsoonal moisture from the south that brought Los Angeles almost unheard of July rain last month is consistent with El Niño's development, as is the drought developing in Panama.

Since 1950, there have been 22 seasons with an El Niño. Twelve brought above-average rainfall, as much as two to three times normal. February, 1998 recorded 17 inches of rain. But El Niño is not the only factor influencing winter storms, and in fact there was no El Niño during 2004-05, LA's single wettest season recorded since the 19th century. 

In most years, equatorial trade winds blowing from east to west across the Pacific tend to disrupt the accumulation of warmer water along the Americas. In El Niño years, those trade winds largely disappear during late summer and fall.  

"The next three months will tell the tale," Patzert said.

But even a strong and wet El Niño winter likely will not be enough by itself to undo the water debt run up during the past three and a half years of drought, Patzert and water experts agree.

"It's not a drought-buster," but could be a "down payment" toward ending the drought, Patzert said.

Also being watched closely is a longer term phenomenon known as the Pacific Decadal Oscillation (PDO) which cycles between wetter and drier phases than tend to last 20 years or so before a phase shift.

Western America has been under the influence of a drier phase that began around the turn of the new millennium 15 years ago.

Patzert sees evidence the PDO may have begun shifting back to a wetter phase, which would be accompanied by a more frequent occurrence of El Niño conditions.  

"That would be the drought buster," Patzert said.

But he emphasized the evidence of a PDO shift is not clear cut, and may not become apparent for several years.

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