SAN LUIS VALLEY —A feather duster probably won't help in the mountains.

Dust is a problem in the high country and it could affect Valley water.

According to the Center for Snow and Avalanche Studies, dust from the April storm event was observed at all CODOS sites across the entire state.

Snowpack in every part of Colorado’s high country is sporting layers of dust, according to a new statewide survey of the state’s winter accumulation.

“This is a low frequency dust season,” wrote Jeff Derry, head of the Colorado Dust on Snow (CODOS)program, in a post about the survey results. “But may be a high consequence snowmelt season.”
He explained dust is darker than snow. Just like a black T-shirt on a sunny day, it absorbs more sunlight, causing what’s underneath it to heat up more rapidly.

“It’s like holding a magnifying glass up to the snowpack,” Derry said.

Each year Derry and his colleagues from Silverton’s Center for Snow and Avalanche Studies dig snow pits throughout the state to check on the layers of dust.

This winter, he found two distinct stripes close to the surface.

A dust storm in early March left one of those layers and another storm in the first week of April blanketed dust throughout the state’s high country.

At each of the 11 sites Derry visited, dust was present somewhere in the snowpack.

Snow melts from the top down. The layers closest to the surface melt through the snowpack, exposing those underneath.

Once dust layers are exposed, they have the potential to speed up snow melt.

Depending on the severity of the dust deposition and where the layers lie within the snowpack, dust can shorten the runoff season by a couple weeks to a month.

In a heavy snow year, like the winter of 2019, that could mean rapid melt in watersheds across the state, making water management much more difficult.

Wolf Creek
Wolf Creek sample site at Wolf Creek Pass was a bear to dig and cost a measurement worker four hours at this site digging the wet, heavy, dense 7.8-foot snow profile with a spade shovel.

The severity of the dust layer nearest the surface is on the upper end of moderate. On May 2, it was 16.5 inches below new snow accumulation and 3.5 inches of new water from the April 30-May 1 storm.
Wolf Creek has dust layers not observed at any other CODOS sample site including Senator Beck. There is a dust layer at snow depth 41 inches at snow depth 35.5 inches and at snow depth 28 inches.
One of the bottom layers is not visible at SASP but nonetheless likely present and the other dust event is unique to the Rio Grande.

 The two lowest layers are light/moderate severity and the other is light. As mentioned the snowpack is isothermal and wet. From April 15-21 the Wolf Creek Summit SNOTEL lost nearly  one inch each day, so when conditions have permitted snowmelt has been healthy, currently it is 126 percent of median.

Spring Creek
Spring Creek snow profile showed 3.4’ snow depth equating to 15.3” of water.
Typically, CODOS found Spring Creek shows the same dust events but of less severity as locations to the south.

This is essentially the case this week. Having a much shallower snowpack dust layers were merged 9” below the recent storm accumulation and is of light/moderate severity. Note that judging severity depends much on weather and light conditions as well as melt water leaching dust down a few inches making it more diffuse and difficult to see. So there are occasions when a site is classified as to severity.