Up to 2 feet of snow by late Friday in favored mountain zones; winter-like avalanche conditions in the backcountry and a new dust layer in the snowpack
SUMMIT COUNTY — A chilly, wet storm started dumping snow on the north-central Colorado mountains early Thursday morning. The storm started with rain and another layer of desert dust that could be a factor in backcountry avalanches when spring conditions return.
Up to 10 inches expected on favored northwest-facing slopes. According to the Colorado Avalanche Information Center, up to two feet of snow can be expected on some of the higher mountain slopes in the most favored zones, from Aspen up through the Flattops and into the Gore Range.
Arapahoe Basin reported two inches of snow early in the day, but at least four inches had piled up in Frisco by 9 a.m. The snow may taper off during the day but will intensify again Friday.
Mountain areas from the San Juans up through the center of the state, the Front Range and the Steamboat zone are under a winter weather advisory. The Gore and Elk Mountains are under a winter storm warning through 6 p.m. Thursday evening.
High temps are forecast to remain near or below freezing through the weekend before a warmup Monday. Lows Thursday night could dip into the single digits, with teens expected for lows through the weekend — in short, winter weather.
Those winter-like conditions will also contribute to a complex avalanche hazard situation in the Colorado mountains. Before the storm rolled in, wet, loose-snow slides were reported around the Front Range in the James Peak area, starting “like clockwork” at 11 a.m., according to the avalanche center.
Here’s the center’s recent bulletin on avalanche activity:
“Activity followed the sun around for a few hours, then spread to all aspects below treeline. Large, loose avalanches were running on northerly aspects by mid-afternoon.”
The CAIC also reported slides from the A-Basin area earlier this week, with the recent storm snow running on the dusty. old-snow layer from an earlier storm that started with a deposition of desert dust. In Chihuahua Gulch, a backcountry rider took a short tumble in a slide on an east-facing slope above treeline.
The current storm also started with another layer of thick red dust and rain, so look for similar scenarios when spring conditions return.
But for the next few days, backcountry travelers will face more winter-like conditions, with fresh snow slabs sitting on the surface of a funky snowpack that was in mid-transition to spring conditions. Slides in the storm layers are possible across most of the backcountry the next few days, with big drifts, new slabs and cornices expected to form across the higher terrain where significant snows are falling.
Get the latest info from the CAIC online, with updates posted Friday, Sunday and Wednesday afternoon.
Dust transport across long distances is nothing new. Scientists have long traced desert dusts from Asia moving eastward across the Pacific, as well as from North Africa, moving west across the Atlantic all the way to South America. When the dust falls into the ocean, it actually fertilizes large areas of phytoplankton, which important biomass at the base of the marine food chain.
Dispersal by wind also helps pollinate forests and other other plants, spreading genetic material across huge distances to increase biodiversity.
What is new is the frequency and intensity of dust events affecting the Colorado mountains. Each year, researchers find more conclusively that the increase can be traced to human activity in the desert southwest, from off-road use, to development of housing and even oil and gas drilling activities. The dust darkens the snow and can speed up the pace of snowmelt by days and even weeks.
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