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What a potentially short and weak La Niña means for SoCal’s ongoing drought

by Natalie Chudnovsky | AirTalk®

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Dried mud and the remnants of a marina is seen at the New Melones Lake reservoir which is now at less than 20 percent capacity as a severe drought continues to affect California on May 24, 2015. MARK RALSTON/AFP/Getty Images

A new report from the NOAA Climate Prediction Center, released Thursday, forecasts a brief, weak La Niña, which may affect the kind of rain, if any, that we’ll get in Southern California.

La Niña, a phenomenon marked by the cooling of water in the equatorial Pacific, is a major driving force behind weather around the globe. Just last month, the forecast was neutral, which meant chances of Los Angeles getting its average of 15 inches of precipitation looked good.

But the new report points to a 70 percent chance of La Niña development in the fall, sloping to 55 percent in the winter. That might mean a drier, warmer winter in the southern tier of the U.S., which doesn’t bode well for SoCal as it enters its sixth year of drought.

Felicia Marcus, Chair of the California State Water Resources Control Board, joined Airtalk , along with Mike Halpert, Deputy Director of NOAA’s Climate Prediction Center, to discuss the report. 

Marcus told Airtalk host Larry Mantle that anytime the odds of La Niña go up, she gets uncomfortable, but that as climate change persists, SoCal weather will be increasingly difficult to predict. 

“We pretty much have to be ready for anything,” Marcus said. “Both drought and flooding. And we know we're going to need to be even more prepared under a climate change world.”

Interview highlights

On the recent drop in California water agencies’ conservation numbers

Marcus: We don't know whether the drops [in water conservation] we're seeing are understandable relaxation given knowledge that the drought is still on but not as bad, or whether it's agencies abandoning their programs.

On why La Niña typically spells a warmer, drier winter for the Southern tier of the U.S.

Halpert: It's not really the changes in the ocean temperatures that have the strongest impact, it’s what goes along with those changes in the ocean. One of the key things we look for when we're declaring La Niña are changes in tropical rainfall. When we see the tropical rainfall shift from the central part of the basin … over towards the west, where Indonesia is on the western Pacific, that has an impact on the jet stream across the Pacific Ocean. And often times when that happens, we see what we term a 'ridge' or high pressure in the gulf of Alaska. Basically, it [the ridge] ends up steering the jet stream and the storm track to the north of southern-central California. Those years often favor wet conditions in places like southern Alaska [and] the west coast of Canada, as well as the Pacific Northwest.

On the variability of climate prediction

Halpert: Last year we didn't see what we expected. And this year, even with La Niña, could we see a pattern where it ends up wet in Southern California? ... It’s not the favored or the likely outcome, but it’s certainly a possible one.

Hear the full discussion by clicking the playhead above.

Guests:

Mike Halpert, Deputy Director of NOAA’s Climate Prediction Center; he is one of 11 forecasters that develop the El Niño-Southern Oscillation Diagnostic Discussion/ Forecast

Felicia Marcus, Chair of the California State Water Resources Control Board

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