A snowboarder on the Park City ridgeline reported an avalanche on Murdock Peak Dec. 21.
They told the Utah Avalanche Center they triggered it remotely, meaning a crack deep in the snowpack traveled and caused a slide somewhere else.
In this case, the snowboarder said they and one other person were riding the low-angle north face of Murdock Peak and saw the steeper northeast bowl avalanche. The slide was 12 inches deep, 50 inches wide but didn’t catch or carry anyone.
UAC forecaster Greg Gagne said the incident is important to keep in mind as a Christmastime storm system rolls into the Wasatch Mountains.
“It's kind of an indication that that buried weak layer that we have down near the ground on those northerly facing slopes will become a problem as we add more of a load,” he said on KPCW’s “Local News Hour” Dec. 22.
The weak layer he referenced is a group of sugary, crystalline facets that don’t stick together. Facets form because the ground is warmer than the snow surface, and it’s easier for them to form in shallow snowpacks.
There are actually two persistent weak layers in the cetnral Wasatch, according to forecaster Nikki Champion.
“We've got that weak snow on the ground from October, November, and then we've got another weak layer about 2 to 6 inches down,” she said. “Doesn't really matter if you find the weak layer at the ground or mid-snowpack. Either way, we've still got that same issue: strong snow over weak snow.”
Avalanche experts say remotely triggered avalanches are why backcountry enthusiasts should be mindful of hiking underneath avalanche terrain — slopes 30 degrees or steeper.
Pressure spreads outward when applied to snow. So especially when there’s a weak layer extending from a flat area into a steeper area, it can travel and cause a slide on a connected slope.
Murdock Peak is located in the backcountry behind Park City Mountain’s Super Condor Express lift, out the back of Murdock Bowl.
Utah Avalanche Center staff were headed out to the debris field to assess the slide Dec. 23. Click here for the observer’s report.
With Utah’s light snowpack and unusually warm temperatures, forecasters say not many people are getting out into the backcountry. They remind anyone who does to report any avalanches they observe online at utahavalanchecenter.org.
