Turnagain Pass

A high consequence, stubborn to trigger avalanche problem lurks above 3000’, where it will be easy to assume a false sense of stable conditions. A stout crust has stabilized the snowpack in the mid and lower elevations, and this crust disappears under the new snow somewhere around 3000’. In the Alpine several weak layers (buried surface hoar and facets) remain preserved deep within the snowpack, under 3-8+ feet of snow. Basically there is an invisible gray line between Treeline and the Alpine where the snowpack goes from stable to a Deep Persistent Slab problem without notice.

Several tracks may be on a slope before someone finds a trigger spot, a thinner area of the snowpack, that takes the whole slope. Because this problem is impossible to assess without x-ray vision, an element of luck will be involved if you ride/ski in big terrain without incident. You can manage this problem with your elevation by sticking to terrain below 3000’ or by choosing low-consequence terrain in the alpine. Don’t forget the bigger your objective, the bigger the size of a potential avalanche. 

Keep in mind:

• Obvious signs of instability like collapsing “whumpfing” may not be present until it’s too late
• Be aware of people above and below you, an avalanche from above could run much further than expected
• Remote triggering is possible from a thinner area of the snowpack
• Snow pits and stability tests may not be representative of the slope you are evaluating

A natural avalanche on Sunburst released mid-storm, likely Tuesday (1/16), and serves as a good reminder that slopes that have already avalanched, during one of the many storms this season, should not be considered safe. This recent avalanche was 3/4 of mile wide, ran 2000’, and filled up the entire drainage of Taylor Creek.

The 1st pit was dug just above the crown on Sunburst at 3400′ in a thinner area of the snowpack. The 2nd pit was a few hundred feet away in the bed surface. This is a good example of the poor structure that is buried 3-8+ deep in many places. 

Cornices have been growing over the last week and could be easy to trigger. Give these features a lot of space and remember they can break further back from a ridge than expected.  A cornice fall also has the potential to trigger a very large avalanche on the slope below.

Fast moving surface snow “sluff” was observed yesterday and it could knock a skier or rider down if you’re not expecting it. You can manage this problem by slowing down and letting the snow move past you. This of course will be more problematic in steep high consiquence terrain where falling would be undesirable and is a secondary risk to the bigger problem mentioned above.