Skiers, snow scientists differ on what a great snowpack looks like
By Stephanie Lynn Gallatin River Task Force
Champagne powder, corduroy, corn snow, Sierra cement, crud.
Skiers have invented dozens of ways to describe snow conditions, which vary from bulletproof ice to effervescent powder.
Great skiing, according to Rich Chandler, environmental manager at the Yellowstone Club, arises from the serendipitous confluence of temperature, wind loading, snowfall intensity and total storm accumulation. “In a perfect world, it is a soft, but stable, underlying base with a storm that started warm and got colder, while depositing slightly less than an inch per hour with no wind for a couple of days,” Chandler said.
By contrast, scientists predicting summer water supply envision ideal snowpack quite differently. Across the arid West, snowmelt feeds the river system throughout the dry season. Deep, dense snow ensures adequate summer flow for many sectors, including agriculture, recreation, fisheries and household use.
The Montana Natural Resources Conservation Service began monitoring snow in the early 20th century to predict water supply for producers. Their extensive monitoring network includes the Lone Mountain SNOpack TELemetry (SNOTEL) station, which continuously measures snow depth, density and temperature.
While light, fluffy powder offers off-piste bliss, dense, packable snow stores more water. Fresh “cold smoke” at Big Sky Resort typically has a moisture content between 3-5 percent, which is better for recreation than water supply. “As a reference, the famed powder of the Wasatch usually falls between 6-7 percent and ‘Sierra cement’ is closer to 12 percent,” Chandler said.
Despite different density preferences, skiers and water forecasters do agree on their endorsement of deep snow. Winter conditions that merit a snorkel while you ski often drive above-average spring runoff. During a normal year, approximately 400 inches of snow pile up at Big Sky Resort while nearby Bridger Bowl receives around 350 inches.
Together, depth and density determine the amount of future water stored in the snowpack bank. This relationship, known as snow water equivalent (SWE), can be used to calculate how deep the water would be if you melted the entire snowpack at the same time. For example, at the time of writing, the Lone Mountain SNOTEL measured 32 inches of snow at 8,880 feet with a density of 25 percent to yield a SWE of 8 inches of water.
Across the Gallatin River watershed, the snowpack bank was average (108 percent of normal) on Jan. 1 according to the NRCS website. Time alone will determine whether or not snowmelt will provide sufficient runoff to satisfy anglers, paddlers and agricultural producers this summer.