Northwest Mountains

It is unlikely that you will trigger a slab avalanche, but not impossible.  Avalanche conditions have quieted down greatly since last week's major storm.  The most suspect terrain is found at upper elevations facing the compass's north half, which don't show signs of recent avalanche activity and extreme terrain.  Although suspect slopes are isolated across the landscape, a large avalanche could be triggered.  If you find yourself in doubt, southerly aspects and low-elevation slopes offer lower-risk options.

In the Northwest Mountains, the persistent slab problem has become unlikely to trigger, and the features of concern are isolated across the landscape.  Many steep slopes, highlighted by the Persistent Slab distribution rose, avalanched naturally during last week's widespread cycle; most of these slopes now lack a slab.  Observations and stability tests on intact snowpacks (no previous avalanche activity) show notable improvements in basal weak layer hardness with clear signs of rounding (1,2).  Lingering concern for a triggered avalanche is a product of variability in alpine terrain due to previous winds.  There could be outlier slopes that are just shallow enough to prevent weak layers from gaining strength.  Even though avalanche conditions have greatly improved in the 10 days since the major Thanksgiving storm, evaluate slopes where you expect to encounter Persistent Slab structure before you enter steep and consequential terrain.

In the Southeast Mountains, the Persistent slab problem has become harder to trigger but more problematic than in the Northwest Mountains. The natural avalanche cycle during the Thanksgiving storm was less impressive and released fewer slopes. Due to less snow during the Thanksgiving Storm, slabs are generally thinner, and the snowpack shallower, which we suspect makes basal weak layers slower to heal.  These two factors make a triggered slab avalanche more likely in the Southeast Mountains.

As the upper snowpack continues to facet and lose strength, stay alert for small loose dry avalanches on sustained, steep terrain.  The snow on top of old bed surfaces is losing strength rather quickly, as shown in this video from Mt. Axtell earlier this week. 

Events: Avalanche Awareness Night is at the Center for the Arts this Saturday. Doors open at 6, show starts at 7. We will have presentations for the first half and live music for the second half of the night. The Beacon Brush Up is then behind the Crested Butte Community School on Sunday from 9 a.m.- 2 p.m.  Details are here.