Study quantifies how 2021’s extreme spring heat waves shriveled Western snowpack
A new study shows that extreme spring heat waves can wipe out mountain snowpack at alarming rates, with big consequences for the West’s water supplies.
Researchers at the Desert Research Institute examined data from 626 Snow Telemetry (SNOTEL) monitoring stations across the region from April 2021, when two record heat waves baked the West. Much of the Rocky Mountains experienced a seven-day period during which maximum temperatures reached up to 6 degrees Celsius above average. Temps were even higher in the Pacific Northwest’s Cascade Range.
That heat drove snowpack to melt at unprecedented rates at 24% of the SNOTEL sites that month, the researchers found.
Dan McEvoy, a climatologist at the Desert Research Institute and co-author of the study, said its findings are a sign of a warming world, with such extreme weather events and rapid snowmelt boding ill for a region gripped by a historic drought.
“You had more time exposed to drying without snow cover than in a normal year, and so that dries out the soils,” McEvoy said.
As a result, dried-out soils soaked up more snowmelt in 2021 before it could run off into streams and reservoirs or recharge groundwater, McEvoy said. In fact, water provided by snow was below average at every Western basin that April, the study found. The biggest drops were in the Great Basin, Rio Grande Basin, and upper and lower Colorado basins.
This story was produced by the Mountain West News Bureau, a collaboration between Wyoming Public Media, Nevada Public Radio, Boise State Public Radio in Idaho, KUNR in Nevada, the O'Connor Center for the Rocky Mountain West in Montana, KUNC in Colorado, KUNM in New Mexico, with support from affiliate stations across the region. Funding for the Mountain West News Bureau is provided in part by the Corporation for Public Broadcasting.