Researchers are trying to unravel the mystery of snow that falls but never shows up in the Colorado river

In the East River watershed, located at the highest reaches of the Colorado River Basin, a group of researchers at Gothic’s Rocky Mountain Biological Laboratory (RMBL) are trying to solve the mystery by focusing on a process called sublimation. Snow in the high country sometimes skips the liquid phase entirely, turning straight from a solid into a vapor. The phenomenon is responsible for anywhere between 10% to 90% of snow loss. This margin of error is a major source of uncertainty for the water managers trying to predict how much water will enter the system once the snow begins to melt.

Although scientists can measure how much snow falls onto the ground and how quickly it melts, they have no precise way to calculate how much is lost to the atmosphere, said Jessica Lundquist, a researcher focused on spatial patterns of snow and weather in the mountains. ...

The snow that melts off Gothic will eventually refill the streams and rivers that flow into the Colorado River. When runoff is lower than expected, it stresses a system already strained because of persistent drought, the changing climate and a growing demand. In 2021, for example, snowpack levels near the region’s headwaters weren’t too far below the historical average— not bad for a winter in the West these days. But the snowmelt that filled the Colorado River’s tributaries was only 30% of average.

It's pretty unsettling to hear that snow can skip melting into water, and how little we understand the process. That's going to throw off all sorts of prediction models, especially with how rapidly things seem to be changing in recent years. So hopefully they can make some good progress towards understanding this soon!