‘Dust on peak snowpack can be a menace’
Research shows dust-on-snow events increasing since early 1990s
Many people in the Yampa Valley make important decisions about everything from recreation to business plans based on the numbers for rain and snowfall, snow pack, cubic feet per second, wind speeds and temperatures.
Colorado researchers who monitor 11 mountain pass sites, including Rabbit Ears Pass, say another important metric to add to the mix should be dust on snow.
Studies show an increase in dust storms in Colorado since the early 1990s, said Snow Hydrologist Jeff Derry, executive director of the Colorado Dust-on-Snow program, or CODOS, which started in 2004.
“Mountains are considered a bellwether for regional and local climate change, and dust on snow has a major impact on how the snow melts,” Derry said.
The dust storm that hit Routt County and the majority of Colorado on May 8 was “a massive event,” Derry said, following a significant dust event that reached Routt County on April 19.
“Dust severity on snow is getting worse in Colorado in the last 30 years, with a lot of variability from years,” Derry said.
Derry said the dust that affects Colorado usually comes from the Four Corners area from northern New Mexico and Arizona and southern Utah. Poor soil health caused by a combination of contributing factors, including oil and gas exploration, off-road vehicle use, overgrazing and high winds in the springtime, leads to the dust storms.
Other factors stem from the warming and drying effects of climate change such as increased stress on vegetation coverage and reduced soil moisture, Derry said.
“A typical dust event from the Four Corners hits the San Juan Mountains worst and then goes northeast into the rest of Colorado,” Derry explained.
Researchers are documenting that Wolf Creek Pass and Red Mountain Pass regions in southwestern Colorado experience the brunt of the dust. Derry classified the San Juan Mountains region as currently experiencing a “severe” dust year. The last year rated severe was 2013.
CODOS is an applied science effort conducted and funded on behalf of Colorado and regional water management agencies with its primary study site at Red Mountain Pass between Ouray and Silverton. CODOS is part of the nonprofit Center for Snow and Avalanche Studies research entity in Silverton, where Derry is the executive director.
On the south side of the west summit of Rabbit Ears Pass, on a sunny and warm morning on May 16, Derry and volunteers dug a large pit in the dusty snow, where the snow depth measured just below average at 1.42 meters. Derry chose a site in a clearing surrounded by trees to protect the dust deposit from winds but not affected by blowing pine needles.
The researcher has monitored and sampled dust on snow at the Rabbit Ears site from mid-April to May since 2005. Derry carefully scraped the top of undisturbed dusty snow into containers to be sent to the U.S. Geological Survey to determine the mineral content and source of origin.
The researcher said dust-on-snow events can translate to earlier and faster spring runoff in local rivers and tributaries within one to two days of a significant dust deposit on the snowpack. Experts say 70-80% of surface water in the western U.S. comes from snowmelt.
“The snowpack is a natural reservoir, so just imagine if you release that reservoir earlier in the season the whole array of impacts and repercussions,” he explained.
The darker snow attracts more sun and heat for faster melting. Spring dust events can increase spring snow melt thus impacting late summer water flows and water quality.
“By tracking the dust layer, it gives an albedo forecast, or the absorption level of the snow surface,” Derry said. “You can get albedo numbers from satellite, but the snow profile tells what we can expect in the days ahead. To get the timing and rate of snow melt, you got to know the albedo. If you have more dust, it absorbs more solar radiation.”
Following the dust storm on May 8, Routt County stayed largely warmer and dry until May 20. Dust remaining on the snow surface from May 8 to 20 ramped up local snowmelt rates, Derry said.
Representatives from the sustainability program at Colorado Mountain College in Steamboat Springs and nonprofit Yampa Valley Sustainability Council joined Derry for the recent local dust monitoring and sampling.
CMC Biology Professor Becky Edmiston said she hopes the college will be able to train students to help CODOS with future sampling.
Madison Muxworthy, YVSC soil moisture, water and snow program manager, said learning more about dust on snow impacts will help YVSC educate valley residents about water resources and water conservation efforts.
Using the dust-on-snow observations, weather forecasts and data from nearby SNOTEL, or snowpack telemetry sites, the CODOS program issues a series of regular analyses posted online at CODOS.org of how dust is likely to influence snowmelt timing and rates. Derry said the combined metrics can help regional water managers improve forecasting, as opposed to reacting.
The researcher was happy snow hit Routt County on May 19 to help cover up the dust storm and provide an “albedo reset.” Dust storms late in spring can cause the most impact if dust remains on the snow surface longer.
“Dust on peak snowpack can be a menace,” he said.
To reach Suzie Romig, call 970-871-4205 or email sromig@SteamboatPilot.com.
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