Snowpack at Snoqualmie Pass is deepest it’s been in 10 years, Washington officials say

It’s been a snowy winter on Washington’s primary East-West route across the Cascade Mountains, with snowpack so deep it broke a decade-long record, according to the Washington State Department of Transportation.

The snowpack at Snoqualmie Pass, which sits along I-90, hit a 10-year high for the 2020-21 snow season at more than 10 feet, the department said in a Facebook post. And as of Friday, the pass has measured 358 inches of snow, which is 14 inches short of exceeding the “10-year season average,” according to the department.

Last season’s snowfall totaled 345 between October 2019 and May 2020, data from the department shows. Ten years ago, there was 498 inches of snowfall.

Snowpack, also commonly referred to as snow-to-water equivalent (SWE), “is a measure of the snowfall in mountain regions … which calculates the amount of liquid water if all of the snow were to melt,” The Daily of the University of Washington reported in April.

Washington’s reservoirs do not have multi-year water capacity, so “much of the region’s water reserves are stored in the upper altitudes as snowfall, which slowly melts and replenishes the reservoirs throughout the summer,” according to the Daily.

“Seattle’s reservoirs, we have two of them, they hold a pretty good amount of water,” Cliff Mass, an atmospheric sciences professor at the University of Washington, told the Daily. “Enough maybe to get through one season, maybe, but the snowpack is an important addition to it. We can get by with what is in the reservoirs, but it’s just on the edge.”