Cascade Mountains’ snowpack: This week’s weather won’t reverse snow drought in Pacific Northwest

This week’s snowfall likely won’t be enough to pull the Pacific Northwest out of its snow drought.

Snowpacks were at a record low across the Western U.S. in early January, the National Integrated Drought Information System reported last week.

Snowy mountaintops serve as water storage for the region. Melting snow provides drinking water to millions of Washingtonians, irrigates crops and sustains healthy freshwater habitats, according to the National Oceanic and Atmospheric Administration’s Climate Prediction Center.

The Cascade Mountains’ snowpack is 40 percent to 60 percent of normal. Record lows also extend to California, Colorado, Idaho, Montana, Nevada, Oregon and Wyoming, with the northern Rocky Mountains facing the brunt of the snow drought.

“It is kind of striking that the pattern here is so widespread,” said Luke Gilbert Reyes, a doctoral student at Washington State University Vancouver who studies snowpack.

Multiple atmospheric rivers dumped snow atop mountains in early December. However, temperatures increased and light flakes turned to heavy rain, resulting in little mountaintop snow accumulation across the West. A dry wave lingered for the rest of the month, worsening the snow drought.

If winter precipitation is constant and temperatures remain cool through March, the snowpack might rebound, Reyes said. However, the current El Niño winter — abnormally warm and dry — will ultimately lead to below-average snow accumulation, he said.

Yet this seasonal weather pattern isn’t the only contributing factor hindering snow levels.

The Pacific Northwest’s mountain snow, typically kept frozen in high elevations, has experienced warming trends since the mid-1990s, according to a study published in December co-authored by Reyes.

On a global level, river basins are experiencing a steady shrinkage in snowpack, according to a study published this month in the scientific journal Nature. Researchers found that climate change is the leading culprit.

The report outlines a 40-year downward trend in 70 of the 169 observed river basins in the Northern Hemisphere. A dozen of the basins experienced an upward trend, while the others experienced no change.

The Columbia River basin is expected to see a sharp decline in spring runoff, according to the study.

“Our results emphasize that human-forced snow losses and their water consequences are attributable and will accelerate and homogenize with near term warming, posing risks to water resources in the absence of substantial climate mitigation,” according to the article.