Climate: El Niño could extend Pacific Northwest drought

NOAA updates seasonal outlook; El Niño likely to persist into spring

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Warmer than average sea surface temperatures prevail across most of the eastern and central Pacific Ocean, as El Niño continues to strengthen.

By Bob Berwyn

FRISCO — Federal weather experts today said they’re more sure than ever that a strong El Niño will persist through the fall and winter, but they are less certain about how the cyclical Pacific Ocean climate pattern will play out across the U.S. The Aug. 13 El Niño update and diagnostic discussion is online here — it says there’s a 90 percent chance El Niño will last through the winter and an 85 percent chance it will last into early spring 2016.

During an El Niño, sea surface temperatures are above average across the eastern and central equatorial Pacific, and this year’s event could be among the strongest on record dating back to 1950, said Mike Halpert, deputy director of NOAA’s Climate Prediction Center.

The pattern also favors a continuation of drought conditions in the Pacific Northwest, according to NOAA’s El Niño experts.

Sea surface temperatures in the ocean region used to assess El Niño strength could soar to 2 degrees Celsius above average, putting this year’s event on par with 1972-’73, 1982-’83 and 1997-’98, Halpert said.

In general, the pattern suggests above average winter precipitation across the southern tier of states, including Southern California. Rain and snow could be below average in the Great Lakes region as well as the Northern Rockies, including the important Upper Colorado River Basin, which is a critical water source area for much of the Southwest, but the links between El Niño and snowpack in the mountain West are not all that strong, the NOAA experts said during a telephone press conference.

“It’s important to remember that, just because something is favored, it’s not guaranteed,” Halpert said, referring to speculation that an El Niño-fueled winter could be a drought-buster for California. One winter of above-average precipitation is unlikely to erase four years of drought, he added.

El Niño tends to bring above-average precipitation  to Southern California, but doesn’t have much of a signal across the northern part of the state, where most of the big reservors are located, said Kevin Werner, director of NOAA’s western region climate services.

“The correlation between El Niño and precipitation are far from perfect,” Werner said, describing drier-than-average conditions during some El Niño years, including 2002, which brought a bitter drought to Colorado and other parts of the West.

Werner said it’s also difficult to discern at this point how El Niño will affect winter temperatures in the West. In the context of global warming, and with a pool of very warm water off the West Coast, there are some concerns that winter moisture will come in the form of rain rather than more beneficial snow that accumulates and runs off gradually in the spring.

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