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Waning El Niño could signal state’s water woes not over 

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Waning El Niño could signal state’s water woes not over

By Kale Williams

Updated 3:42 pm, Friday, February 19, 2016

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Photo: Courtesy, NOAA

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Even if El Niño brings lots of rain to California throughout the winter, it might not bring enough snow to replenish the snowpack. The last large El Niño hit California 1997-98 and resulted in average snowfall in the north. That was fine then, but this year we're starting from nothing.

Average Pacific Ocean sea surface temperature anomalies (°C) for the week of August 5.)

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As the El Niño weather pattern wanes, chances of a La Niña pattern setting up in the fall are increasing.

El Niño, as all things must, will be coming to an end over the next couple months, possibly to be replaced by its sister phenomenon, La Niña, which could spell a drier than average summer and fall, a foreboding prospect for a thirsty region suffering through an extended drought.
The International Research Institute for Climate and Society released its seasonal forecast and, as expected, the warm equatorial waters in the Pacific Ocean known as El Niño, which many hoped would spell relief for California’s ongoing water woes, have peaked and are beginning to cool.

The surface temperatures in the ocean are expected to remain substantially above average until May, but will decrease steadily through August, with the El Niño effect all but gone by midsummer. Still, despite a nearly bone-dry February, chances of above average precipitation remain for March, but it will have to be a very wet month to do any damage to the drought.

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“March is key,” said Tony Barnston, chief forecaster with the institute, which is a cooperative venture between Columbia University and the National Oceanic and Atmospheric Administration. “That’s where we’re hoping to make up a lot of ground.”
April and May are typically drier months in Northern California so, even with an elevated chance of above-average rainfall, the late spring probably won’t provide much relief, Barnston said.
Looming beyond the spring is the possibility of a La Niña pattern developing, signified by cooler surface temps in the Pacific. Weather being what it is, Barnston said, things get hard to predict that far out, but chances for a La Niña pattern to set up stand at 51 percent. While that effectively amounts to a coin flip, chances are still higher than the average year.
“We’ve seen some La Niñas come in after strong El Niño years,” he said. “We saw one after the El Niño of ’97-’98, and there was a borderline La Niña after the ’82-’83 El Niño. If we do get it, it usually means below-average precipitation for the winter months.”
All of this comes as the National Oceanic and Atmospheric Administration announced that the first month of the year was the warmest January on record and the ninth consecutive month of record heat around the globe.
The moral of the story is: keep your showers short and your gardens drought-tolerant. We aren’t out of the woods yet.
Kale Williams is a San Francisco Chronicle staff writer. E-mail: kwilliams@sfchronicle.com Twitter: @sfkale