Turnagain Pass

A beautiful day is on tap with clear skies, temperatures in the teens to twenties, and light winds. Unfortunately, the warm temperatures and rain earlier this week have created a variable melt/rain crust on the surface throughout the forecast zone. The crust makes skiing and riding conditions challenging, especially at lower elevations. Below 1500′ yesterday  we found a thin breakable crust over soft snow combined with marginal snow cover over alders. At higher elevations and in areas that had been exposed to strong winds from late last week the crust is supportable and travel conditions are a bit easier. The travel conditions are likely the biggest hazard of heading into the backcountry today, but remember that low danger does not mean no danger.

Strong winds at higher elevations yesterday were transporting what little snow was still available into fresh wind slabs. Since most of the snow surface is covered in shiny rain crust the fresh wind slabs stand out like a sore thumb, with a more matte appearance from very fine wind transported snow grains. On the few test rolls we found yesterday these wind slabs were fairly stubborn, but in steep terrain at higher elevations it will be possible to trigger a wind slab up to 1′ deep.

The warm temperatures also appear to have reactivated some of the glide cracks in the area (e.g. Seattle ridge) so be on the lookout for fresh glide activity. Identifying active versus inactive glide cracks can be tricky but you can look for visible dark ground surface in the cracks as an indication of recent activity. This is harder to do in areas with a thinner snowpack where older glide cracks have not been filled in as much, like on the southern end of the forecast area. If in doubt try to avoid spending time underneath these unpredictable hazards.

Melt/rain crust from 2000′ on Lipps. This was the most common snow surface we found yesterday and it provided relatively consistent supportable ski conditions. Photo 12.29.21

In some areas the melt/rain layers penetrated deeper into the snowpack creating multiple layers of melt freeze within the upper snowpack. Photo 12.29.21

Where we found fresh wind deposited snow we were able to get some short shooting cracks. Photo 12.29.21

It has been over a month since we started talking about a weak layer of buried facets and it is now very unlikely for a person to trigger an avalanche 2-5+’ deep on this layer, but not impossible. In areas with a thinner overall snowpack, such as the southern end of the forecast area near Lynx Creek, Silvertip Drainage, and Johnson Pass, there is a higher likelihood because it is easier for the weight of a skier or rider to penetrate into the weak layer. The same is true for thin spots in the snowpack like near rocks or partially buried trees. One benefit of the melt/rain crust is that it should make triggering a deep persistent avalanche even more difficult. The amount of strength the crust added to the upper snowpack depends on it’s thickness. Lower elevation areas where there is a very thin crust over dry snow will have a gained less strength. We hope that the refreeze after a few days of warm and wet weather has put this weak layer to bed, but it is still on our radar due to the high consequences of triggering a deep persistent avalanche.