Backcountry Conditions Update
Issued 7:15 am, November 20, 2017, by Evan Ross
A large winter storm on November 17th has kicked off our winter season. This storm left the area with a Persistent Slab avalanche problem and numerous skier triggered avalanches over the weekend as seen on the Observation Page. This dangerous avalanche activity was reported from both our area and around the state. Between this avalanche problem and all the recently buried rocks, backcountry travelers need to stay heads up this week.
The November 17th storm deposited over 20” of snow at Schofield Pass in the northwest portion of our forecast area, and 9” of snow at the more centrally located Crested Butte Mountain Resort. These numbers help highlight where the mountains received enough snow to create the current Persistent Slab avalanche problem. There are two ingredients necessary for this avalanche problem: a) More than 10” of new snow on the 17th, and b) that storm snow buried old weak layers from October. These conditions primarily line up in the Paradise Divide and Kebler Pass portions of our forecast area, at near and above treeline elevations, on slopes facing northwest to northeast. West and east facing slopes have appeared less reactive, but could still harbor the Persistent Slab issue on shaded portions of the slope. Moving to aspects further south around the compass rose, there is only the November 17th snow on the ground, thus no current avalanche problem. Ground debris just under the snow surface would be the main hazard.
This video from before the November 17th storm highlights where old weak snow is at the bottom of the snowpack. While this video on November 18th highlights the current avalanche problem and the additional hazards of a small avalanche causing traumatic injuries as it pushes you into uncovered rocks or ground hazards.
Your ideal terrain should have one layer of snow on the ground with a smooth grassy ground surface like this:
Stay away from slopes over 32 degrees in steepness with old weak snow on the ground that look like this:
The Crested Butte Avalanche Center will post the next conditions update on Wednesday November 22nd. Full operations and daily avalanche advisories will begin after enough snow accumulates.