Professional Observation

Observation Details

Signs of Unstable Snow

Key Points

I wanted to get a look at wind transport and monitor the persistent slab structure at the north end of the forecast area.

• We got localized collapses and cracking on basal facets above about 9000 feet. Below that elevation the facets seemed anchored and broken up by sage. Between 9000 and our high point of 9800 feet (near treeline in this area), the weak layer was continuous, but the overlying slab was highly variable thanks to wind scouring and deposition. We dug a snow pit near some of our collapses and got propagating resulting in the facets (see profile).
• We found thin, stiff wind slabs on cross-loaded features near and below treeline. These cracked around us at kick turns and on small test slopes, especially when we undercut the slope first.
• There were periods of moderate to intense blowing snow above about 8500 feet all day. Transport was more intense at upper elevations and while we did not get to that terrain, I would expect wind slabs there to be a little bigger and a little more sensitive.
• The snowpack is generally thin in this drainage and we hit a number of rocks on our descent.