La NiÃ±a pattern means cooler temps, more rain
By TIM HEARDEN
Atmospheric conditions that promised a wet winter for the Pacific Northwest and California have intensified in the past few months, weather experts say.
Officials from the U.S. Climate Prediction Center and elsewhere have said since June that a La NiÃ±a weather pattern was settling in, meaning cooler temperatures and higher-than-normal precipitation in northern areas.
What looked like mild conditions a few months ago are becoming "a borderline strong event," said Mike Halpert, the climate center's deputy director in Camp Springs, Md.
"We do see this lasting through the winter," Halpert said. "It certainly will impact temperatures and precipitation throughout good parts of the U.S. for a good part of the winter."
Unlike El NiÃ±o's strong southern storms, La NiÃ±a occurs when unusually cool equatorial temperatures push storm systems north.
Last winter, strong El NiÃ±o conditions combined with an unusually long period of arctic oscillation to hammer much of the country with inclement weather, bringing a persistent parade of rain clouds that broke precipitation records in some areas of the West.
With the transition to La NiÃ±a came a wet spring and cool summer that have hampered crop development in much of the West. The mild conditions have caused a later-than-normal harvest for numerous commodities, including almonds, walnuts, prunes, grapes, silage corn, tomatoes and rice.
Several showers in the last couple of weeks have further hampered the almond harvest in California, as some growers have had to wait for their fields and their nuts to dry.
And California apple growers are seeing a lighter crop this fall because of a freeze that occurred in late May, said Ann Wofford, executive director of the Apple Hill Growers Association in Camino, Calif.
"It's going to be a lighter crop than years that there isn't snow right before Memorial Day. That's the kiss of death right there," she said. "Apples ripen at different times -- anywhere from mid-August through mid-November. So what you lose sometimes are the earlier ripening apples. When people say there are no apples, there are. They're just coming along."
The past year's abundance of rain and snow pushed much of California and the West out of a prolonged drought, according to the U.S. Drought Monitor.
With La NiÃ±a, a persistent trough has remained over the Northwest for much of the summer, bringing below-average sea surface temperatures along the West Coast, Halpert said.
"It's something you expect to see during the winter but not necessarily the summer," he said of the low-pressure system.
The climate center's three-month outlook predicts cooler-than-normal temperatures along the coast and at least an even chance of cooler temperatures inland.
As for precipitation, the outlook projects above-normal rain and snow throughout the Pacific Northwest and Northern California over the next three months, and well above normal precipitation along the coasts of Washington and northern Oregon.
The southern half of California and much of the southern United States will be drier than normal, according to the climate center.
U.S. Climate Prediction Center: http:// www.cpc.ncep.noaa.gov/