Turnagain Pass

There was no new avalanche activity reported yesterday. Though once again, few people are venturing into avalanche terrain, including myself. We did get some additional photos sent in of the natural cycle that occurred two days ago (see photo below as well as the link). These avalanches were breaking in the weak snow near the ground and taking the majority of the snowpack with them. Triggering a large slab that sits on the brink is the essence of our primary concern.

Without much change in the weather, it will take a person, group of people or a snowmachine to trigger one of these avalanches. After this last storm the slab is becoming thicker, up to 3’ in places. This can make it harder for your weight to impact the weak layer at the base of the pack and trigger a slide – but the consequences are high.

Below is South facing Lipps Ridge on Turnagain Pass. Avalanche occurred naturally late on 1/4 or early 1/5 (SSW, 3,400’)
 

A few words on snowpack assessment:
Information has been limited since the end of the weekend’s storm. With little visibility and very few people testing the steeper slopes our main clues for evaluating the snowpack continue to be snow pit data and collapsing.

Snow pit data: What we are finding is a slab between 2 and 3 feet thick composed of all the December and January snow (4.8” water equivalent at 1880ft). Under this is the well documented weak faceted snow above and below the December drizzle crust. Stability tests are showing that it’s getting harder to collapse the weak layer(s), but once failure occurs all bets are off and large dangerous avalanches are likely if the slope is steep enough. 

Collapsing: Several people, including our staff, continue to report collapsing while traveling. This means a person can trigger a failure in the weak faceted snow and subsequently an avalanche. What this tells me is that even though the pit data says it should be hard to trigger a slide, maybe it’s not that hard after all. These obvious signs of instability should always trump pit results.

Below 1,500’ a series of crusts and wet snow make up the snowpack and triggering an avalanche is unlikely.