A less predictable, weaker weather system predicted
By TIM HEARDEN
Don't get too hopeful that El NiÃ±o will rescue California from its three-year drought, weather forecasters warn.
For weeks, farmers have spoken wistfully about early predictions that the atmospheric phenomenon could bring a long-awaited wet winter to the Central Valley.
While computer weather models early this summer were bullish on the prospect, forecasters now believe that El NiÃ±o this year will be mild at best, and that the best chances for above-average rainfall are in Southern California.
"A few weeks ago, a lot of the indicators were that El NiÃ±o was robustly developing across the tropical Pacific," said Steve Goldstein, a forecaster for the National Weather Service in Sacramento. "Now, pretty much every sort of predictor indicates we will at least be in a weak El NiÃ±o this winter. The weaker the El NiÃ±o is, the more uncertain that forecasting is."
El NiÃ±o is an atmospheric change marked by the warming of surface waters in the tropical Pacific. Typically, a strong El NiÃ±o 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, said Maury Roos, chief hydrologist for the California Department of Water Resources' flood management division.
"The line from wet to dry is usually somewhere in California," Roos said. "It makes a big difference whether it's near the Oregon border or by, say, San Jose."
Any chance of a rainy winter would be welcome news for the Central Valley's farmers, who've faced drastic state and federal water cutbacks because of the drought. In many parts of the valley, water shortages prompted farmers to fallow ground and pull out orchards and vineyards, while others took emergency measures to help permanent crops survive until the water supply improves.
This week, the U.S. Department of Agriculture added Merced, Stanislaus and San Joaquin counties to its list of major drought disaster areas, bringing the number of counties to receive that declaration to 21. Twenty-nine counties adjacent to those counties have also been designated disaster areas.
Among those who are hoping for a strong El NiÃ±o are California's ranchers, considering that 85 percent of the state's grazing land is rated as poor or very poor.
"Wintertime is when the greatest degree of animal rangeland comes into fruition," said Matt Byrne, executive vice president of the California Cattlemen's Association. "If you can coincide wet weather with cattle out on the range, it would certainly be a positive thing."
Roos has reason to be optimistic. He said only three periods of drought in California in the past century have lasted longer than three years, albeit twice - from 1929-1934 and from 1987-1992 - they lingered for six years.
If the valley were to average even 110 percent to 120 percent of normal rainfall this winter, that would be enough to virtually fill the state's reservoirs, which are now at 79 percent of their normal volume and about 50 percent of capacity, he said.
More rain would be needed to begin to solve the problems south of the Sacramento-San Joaquin River Delta, he said. The protected status of the Delta smelt has contributed to Delta pumping restrictions, so water would have to overflow from the reservoirs on the east side of the San Joaquin Valley.
At Shasta Lake, the keystone of the federal water system known as the Central Valley Project, a wet year could fill the lake, Bureau of Reclamation spokeswoman Sheri Harral said.
The surface of the lake is now 121 feet below the rim and is expected to drop to 137 feet, but 70 or 80 inches of rainfall could bring the reservoir up to near capacity, she said. Seventy or 80 inches is a little above Shasta's average rainfall.
"The year that we were 230 feet down (in 1977), which is our historical low, we filled the very next year with 98 inches of rain," Harral said. "They were anticipating it would take a few years to fill."
As it is now, there's been a persistent area of warm water north of Hawaii, and the Arctic Ocean is warmer this year than it was last year, Goldstein said. Both factors can increase storminess in California, as can a body of warm water off the coast that could be developing as a result of the current heat spell, he said.
"Fall could get off to a decent start," he said. "We're just kind of waiting to see."