Professional Observation

Observation Details

Signs of Unstable Snow

Key Points

Went out looking for the isolated poor structure in the upper snowpack in Virgina Lakes. We were able to access the shoulder of Mt. Olsen from Lundy canyon parking by ascending south facing bowls above the road.

• Steep south-facing snow below 10000′ has gone through enough melt-freeze cycles to be supportable and provided for efficient travel on the up and down.
• Once over the ridge into north-facing terrain in the Virginia Lakes drainage we found dry surface snow in a variety of forms including knife-hard wind slab, sastrugi, breakable wind crust, boot-top settled snow, and loose near surface facets.
• Variation in surface layers every few meters means there is not much continuity in the structure of the upper snowpack.
• We were able to find good expamples of poor structure (see photos) within pockets of sheltered, steep, NE facing snow near treeline.
• This structure is mainly concerning for the future. At present it amounts to stubborn x isolated and small, but in the event of a significant new load the structure will begin to connect terrain features and it is worth starting to track and think about it now as we move into a week of unsettled winter weather.