DENVER, CO - Dust blown in from the Southwest settled on snow over many of Colorado's mountains during this week's storm and will eventually affect how fast the snowpack melts and possibly how much water the state can hold onto.
Researchers say the dust kicked up from Arizona, New Mexico and Utah by southwesterly winds fell in Steamboat Springs, Summit County, Vail, Aspen and the San Juan mountains. Dust was also scattered in the snow that fell along the Front Range but it's likely that dust could have been carried by southeasterly winds from other areas too, including parched southeastern Colorado, the San Luis Valley and the Arkansas River Basin, state climatologist Nolan Doesken said.
Jeffrey Deems, a research scientist for NOAA in Boulder, said dust on top of snow can absorb up to twice as much sunlight as clean snow, speeding up melting. He compares the effect to wearing a dark T-shirt on sunny day.
This week's dust storm was the second widespread one in Colorado's mountains this season. Another storm on April 8th left a thick layer of dust in the state's snowpack, which has now been boosted to 79 percent of the peak average thanks to this week's storm.
"It's kind of a mixed blessing now," Deems said of the new, dusty snow.
More snow is in the forecast but whenever the dust layers from this week and earlier this month are eventually exposed, there will be a significant speed up in the melting of the snow at that time, said Chris Landry of the Center for Snow and Avalanche Studies in Silverton. The center is studying the impact of dust on snow for water providers across the state -- including Denver Water and the Bureau of Land Management -- and periodically checks sites at mountain passes across the High Country for dust.
If clean snow keeps falling the impact will be delayed, Landry said, helping farmers without storage who don't need irrigation water just yet and rafting companies hoping to attract customers to big flows later in the season.
Flows don't have as much of an impact on water providers with reservoirs, which have plenty of room after two straight years of drought, but Colorado's vast mountains can hold more water in the form of snow than reservoirs can.
An early snowmelt would help farmers in northeastern Colorado a bit. As the snow fell this week, crews for the Central Colorado Water Conservancy District worked in the mud to get its lined gravel storage pits ready for the flow. The water they collect will be used by 500 farm families in Weld, Adams and Morgan counties, district executive director Randy Ray said.
Like everyone, he'd prefer a slow, steady flow of water but, as a junior water rights holder, he said the district would take what it could get.
"We're ready to take water if it comes down fast," Ray said.