SACRAMENTO — Climate forecasters are issuing fresh warnings that much-anticipated El Nino conditions won’t be enough this winter to bring California out of its historic drought.
The federal Climate Prediction Center is continuing to watch for El Nino, but its forecasters say the chance of it developing in the Northern Hemisphere this fall and early winter is only 65 percent.
Earlier this summer, the agency had said there was an 80 percent chance an atmospheric pattern would develop that is often marked by strong storms pelting southern and central California.
At any rate, models suggest the El Nino pattern will be weak, National Weather Service warning coordinator Michelle Mead observed in a weather bulletin she sent out via email.
“Remember, El Nino is a poor predictor of winter rainfall across Northern California,” she wrote. “Only strong El Nino events are tied to a potential for a wet winter, but that is for Southern California. Drought conditions are likely to continue in our area and there is not an expectation that El Nino will alleviate or end the drought conditions at this time.”
El Nino is an atmospheric change marked by the warming of surface waters in the tropical Pacific. Typically a strong El Nino means more rain than usual in California and less in the Northwest, but a weaker system could leave much of northern and central California in a dry belt.
El Nino helped California emerge from a three-year drought in the winter of 2009-2010, bringing a persistent parade of rain clouds and cool temperatures that filled reservoirs and broke precipitation records in many areas.
However, Mead has cautioned that El Nino conditions don’t always mean copious amounts of rain and snow, especially in northern areas where the rain is needed to replenish reservoirs. California’s historic drought year of 1976-77 was an El Nino year, she has said.
Ocean-surface temperatures have been increasing in the equatorial region this summer, which has enhanced tropical rainfall and prompted weather prognosticators to predict that an El Nino of some strength will persist this winter.
Many farmers have held out hope that a developing El Nino atmospheric pattern in the Pacific Ocean will mean a wet winter.
But “the atmospheric connection to that has yet to develop,” Mead said in an interview this week. Nonetheless, forecasters believe El Nino should peak at weak strength during the late fall and early winter, she said in the bulletin.