[californiadisasters] Pacific may be gearing up for return of La Niña

Pacific may be gearing up for return of La Niña

Forecaster calls it 'diva of drought'

By Robert Krier, UNION-TRIBUNE STAFF WRITER

Tuesday, May 11, 2010 at 12:02 a.m.

Goodbye, El Niño. Hello, La Niña?

It's by no means guaranteed, but conditions in the Pacific Ocean seem to be shifting toward the periodic phenomenon that almost always robs rain from Southern California and the Southwest.

"Right now, I'd say the dice seem loaded for an imminent La Niña," said Bill Patzert, a long-range forecaster at the Jet Propulsion Laboratory in Pasadena. "It's not a good sign. La Niña is what I call the diva of drought for the Southwest."

Among the factors for the El Niño and La Niña cycles are the sea-surface temperatures in the Central Pacific. During El Niños, which create better odds for a wet winter in Southern California, those temperatures are higher than average over several months. Such conditions have existed since last summer, and much of the state experienced a wetter-than-normal winter and spring.

In the past several weeks, ocean temperatures have dropped significantly. The official forecast from the Climate Prediction Center — part of the National Weather Service — is that El Niño conditions in the Pacific are on their way to becoming neutral. The weekly statement the center released Monday said there is a "growing possibility of La Niña developing during the second half of 2010."

"Since we have not issued a La Niña watch, that would imply it's still under the 50 percent threshold," said Mike Halpert, deputy director of the center. "I suspect that as each week goes by, that possibility becomes greater."

Watches are issued when conditions are favorable for the development of La Niña within the next three months. A watch could be issued in June, Halpert said.

David Pierce, a climate researcher at the Scripps Institution of Oceanography in La Jolla, said it's too early to pull the trigger on La Niña. He said we are on the wrong side of the "spring predictability barrier," a period when computer forecast models have historically had a low skill level. Scripps' climate model is projecting neutral conditions later in the year.

About a third of 20-some computer models from various agencies around the world are already projecting La Niña conditions, and the rest show neutral conditions persisting.

If La Niña prevails, "Nobody should be shocked," Patzert said. "In Southern California, we get more dry years than wet years. We always pray for El Niño, but we usually get La Niña."

Regardless of what the forecasters predict, Wendy Martin, drought coordinator for the California Department of Water Resources, said she is planning for a drought year. She said many people have asked if the drought is over, seemingly seeking "psychological permission" to use more water.

"Water is a precious resource in California," Martin said. "We always have to conserve."

Source: http://www.signonsandiego.com/news/2010/may/11/pacific-may-be-gearing-up-for-return-of-la-nina/

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