Near Treeline Obs

CB Avalanche Center 2016-17 Observations

Location: Paradise Divide Area
Date of Observation: 11/27/2016
Name: Evan Ross
Subject: Near Treeline Obs
Aspect: North East, East, South East
Elevation: 11,000

Avalanches: Remote triggered one persistent slab from a couple hundred feet away. Shooting cracks spanning multiple aspects of a gully that pulled out a small avalanche on a steeper 40ish degree slope.
Weather: Snowfall rates in the S1-S5 range throughout the day. Gusty down valley winds blowing, swirling and drifting new snow about. Never made it to ridegline.
Snowpack: HS about 50-60 cm on East and Southeast Aspects. Generally fist hard snow consisting of the Thanksgiving and the current storm without an obvious or reactive interface between them. These storms where resting on a varying thickness and generally soft crust just above the ground. No signs of instability on the slopes traveled. This would have likely been a different story on slopes with additional wind loading.

HS about 65-70cm on Northeast aspects. The Thanksgiving storm had more slab structure 4f- and was sitting over about 10-15cm of 2mm faceted particles. Shooting cracks and collapses while traveling near these slopes. Persistent slab avalanches felt likely to trigger on convex terrain features or slopes over 35 degrees. Small NSF also looked to be present at the interface of the Thanksgiving and todays storm, though didn’t get much time to look into it more.

Below treeline slopes generally lacked enough snow for an avalanche problem, except for potentially a very isolated and wind effected terrain feature.

65cm crown of a small remotely triggered persistent slab.

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Flank profile dug into some shooting cracks.

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Shooting cracks ran down the middle (northeastern) and right (norther) slopes of this gully.

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