Thursday, Sept. 16, 2004 | 10:59 a.m.
Five consecutive winters of disappointing snowfall in the Rocky Mountains have left the Colorado River and Lake Mead high and dry, but some climatologists say the coming winter could be better.
One of the factors that climatologists believe portends an increase in precipitation in the southern Rocky Mountains is El Nino, the irregular warming of the Pacific Ocean off the South American coast. Climatologists at the federal government's National Oceanic and Atmospheric Administration say they have detected the start of an El Nino.
"With the El Nino, you generally get more rain and snow in the Southwest," said Tim Barnett, a climatologist with Scripps Institution of Oceanography in La Jolla, Calif. Barnett said a related factor called the North Pacific Oscillation, a measure of the pool of colder water in the ocean, also seems to encourage more precipitation in the region.
The direction "that it appears to be going in right now appears to favor increased precipitation," he said.
Barnett said computer models in his laboratory have pointed to the climate factors emerging for about a year now. But even if they exist, it doesn't mean that tons of much-needed snow will fall in the mountains.
"The thing that concerns me about it is that it will be weak," he said of the El Nino. "Will it have enough juice to do something for us? We can't really answer that question.
"We have a couple of chances, but we don't know what's going to happen," said Barnett, who is in Montana doing climate research. "The odds are certainly more in our favor now."
Jan Null, president of the private Golden Gate Weather Services in San Francisco, agreed with his colleague's assessment.
"It does look like there's going to be an El Nino this winter, but not all El Ninos are the same," Null said. "This is not forecast to be a strong event, so the bottom line ends up that you're taking the same odds you have in any year."
Over the course of the last month, the U.S. Department of Agriculture, in connection with regional climatic observers, has seen some signs that the drought in Colorado and in particular in the mountains has eased up, although "extreme drought," the worst level, still grips much of the West.
Pat Mulroy, water authority general manager, said any easing of drought conditions in the Rocky Mountains would be "wonderful."
However, she noted, Lake Powell, Lake Mead's upper reservoir, has less than 38 percent of its capacity.
"It's going to take several years of heavy snowfall for Lake Powell to recover," Mulroy said.
Mulroy said increases in precipitation could help the demand on Lake Powell.
"If we just have a normal year it would help stabilize Lake Powell," she said.
Ken Albright, water authority resources director, said seasonal precipitation already appears to have eased drought conditions in the Rocky Mountains.
"The drought outlook does appear a little better," he said. "We're hoping this is a sign of relief but Mother Nature is her own little animal, so we'll see."
The drought that has parched the West has led to what many hope will be long-term changes in the way water is used in the desert. Water officials in Las Vegas have instituted water-saving measures that have trimmed 22 percent off the 1987 per capita usage rates in a so-far successful effort to stay within the federal limit of how much water Southern Nevada can take from Lake Mead.
The drought also has accelerated the Southern Nevada Water Authority's drive to bring in more water from other sources than Lake Mead, which now provides 90 percent of the region's drinking supply. Within a few years water authority planners hope to begin bringing ground water into the local system, an effort that within a decade could double the available supply.
Vince Alberta, water authority spokesman, said that despite the work, the agency would like to have a few good snowfalls in the Rockies.
"It's encouraging," he said of the climate estimates. "It would be a welcome sight."
But he cautioned that after years of below-average snowfall, it would take more than just an average or even one above-average snowfall to correct the slide.
"It will take a number of years for us to recover from this worst drought on record and for reservoirs to be restored, but it leaves room for optimism," he said. "In the coming years we, as a community going forward, are still going to have to be very conscious of our water use and remain 'water smart' so we become a sustainable community.
"We've made a lot of progress over the last several years. We've benefited from that, but we need to continue with that vigor, that enthusiasm," he said. "There's no question that the drought has reinforced the importance of having multiple sources to draw from, which helps insulate you from what we've been experiencing."
archive
