Snowpack remains well below average
February 26, 2012
EAGLE COUNTY – Colorado’s snowpack needs to play catch-up throughout the rest of winter to put statewide water supplies at healthy levels.
The Colorado River Basin snowpack, Eagle County’s river basin, started February at 69 percent of average, slightly lower than the statewide 72 percent average, but managed to creep up a few percentage points to 74 percent due to a few snow storms here and there, said Mage Skordahl, the assistant snow survey supervisor at the National Resources Conservation Center’s Snow Survey Office in Denver.
Those percentages represent the snow water equivalent – the amount of moisture that’s in the snowpack.
“We finally started getting some snow storms on the western side of the (Continental) Divide, which we hadn’t had much of that,” Skordahl said. “Conditions are improving, but at this point in the season you really have to be well above average for the rest of the season to meet our April 1 average numbers. I would say at this point, that’s pretty unlikely.”
The forecast for stream flow volumes from April through July are all below average as of now, at about 70 percent for the state, she said. But luckily, this winter comes on the heels of a really good winter in 2010-11, so many of the reservoirs are full.
“Statewide, (water) storage is average or above average,” Skordahl said. “About 80 percent of spring and summer stream flow comes from mountain snowpack.”
Locally, reservoir storage is healthy, but reservoirs are less important to Eagle County than they are to other areas in the state. Diane Johnson, spokeswoman for the Eagle River Water and Sanitation District, said reservoirs here are “more strategic – they do not serve as a direct water supply.”
“Our reservoirs serve to replace our depletion in the streams,” Johnson said. “It’s still important for us to have them full – we expect them to fill this year.”
Stream flow is what matters most for Eagle County, though, and it’s still a little too early to know whether the below-average snowpack will have effects on the flows this spring and summer.
“The snow pack, for us, is one component of the picture,” Johnson said. “Another component is what the weather does in the late spring and early summer, in terms of how long does the snowpack last (how fast or slow is the snow melt cycle), and then what’s the summer weather like.”
Johnson said the water district uses 2002, an exceptionally dry year, as one example of what can happen. But then a year like 2009-10, which started out very dry, picked up in terms of snowfall late in the season before it all came crashing down with extremely hot June temperatures.
That was the year Eagle County had its 100-year flood event, proving that temperatures in the spring and summer play a huge role in determining summer stream flows.
Last winter, which broke records in terms of snowfall, is another example of the importance of temperature. A year that had the potential to cause floods throughout the valley turned out to be mellow, with cooler spring and early-summer temperatures keeping the snow melting at a steady, gradual pace. The result was a 2011 summer that was great for everyone – rafters, kayakers, fishermen and the water supply.
Johnson said it’s still February, though, and March is the month to look out for because it’s typically the snowiest month.
Johnson said that after the 2002 winter, the water district invested in its system to protect the community from dry years in the future.
“We feel a lot better about knowing we can do things to get through it better (than we could in 2002),” Johnson said.
Snowpack and winter recreation
As for the snowpack itself and what it means for snow sports enthusiasts for the rest of the winter, the weak, faceted base layers of snow will stay put until the spring, said John Snook, a snow scientist with the Colorado Avalanche Information Center.
“There’s no question about it,” Snook said of the weak snowpack
remaining across the state. “That’s really our concern for the long-term – there will be an elevated avalanche concern throughout the spring.”
The way that weak, rotten layer of sugary snow should end up dissipating, however, is during the melt-freeze cycle in spring, Snook said. That’s when surface snow melts in the afternoons and water percolates down into the snowpack, causing it to eventually lose its layered configuration, he said.
But, the snowpack could also still go through what Snook calls a wet slab cycle, meaning that when that water percolates down into the snowpack, the water can lubricate the layers causing it to lose the ability to hold together, which could create wet slab avalanches.
“That facet layer will be around at least through April, and possibly into May,” Snook said.
Assistant Managing Editor Lauren Glendenning can be reached at 970-748-2983 or firstname.lastname@example.org.