Turnagain Pass

Winner Creek: Skiers triggered avalanches failing on a layer of buried facets sitting on top of a crust. The slabs were 1′ deep on average, with some pockets as deep as 3′. Some of the slabs pulled out on slope angles less than 30 degrees. Nobody was caught.

Skier-triggered avalanches failing on buried facets in the Winner Creek drainage yesterday. Photo: Mike Welch

We are in the midst of another northwest wind event as high pressure moves into the area. Strong winds are expected to continue through today, with sustained ridgetop speeds of 25-40 mph and the strongest winds towards the south end of Turnagain Pass. These winds will be blowing snow into sensitive slabs up to a foot deep, making it easy to trigger an avalanche on wind-loaded slopes today. These northwesterly winds often get channeled up the Sixmile creek drainage near Hope, and get funneled around the south end of Turnagain pass, resulting in strong southerly winds at mid- and lower elevations on the skier side of the pass. This makes it tricky to identify a consistent loading pattern during these wind events, since wind directions will usually change drastically with elevation.

Today it will be important to pay attention to how winds are redistributing snow. Some signs may be obvious from a distance, like wind blowing off ridgelines or across slopes, or fresh avalanche activity. Others may be more obvious immediately around you, like cracks shooting out from your machine or skis, or the feeling of a stiff, punchy slab at the surface. We saw avalanche activity during a similar wind event last Thursday (details here and here), and can expect to see more of the same today.

Multiple weak layers in the upper 3 feet of the snowpack continue to produce avalanches and show warning signs in our area. Strong winds today will place an additional load on these weak layers while building a stiffer slab on top of them,  increasing the likelihood of a person triggering an avalanche. These persistent weak layers are tricky, because they have become stubborn enough that they are not always giving us direct feedback like cracking and collapsing before avalanching. But with multiple avalanches failing on these weak layers in the past few days, they are clearly still cause for concern.

These layers are widespread through our area, so navigating avalanche terrain right now requires elevated caution. If you are trying to access steep terrain (after assessing the wind slab problem mentioned above), consider the consequences of getting dragged down a slope in an avalanche. Give yourself and your partners an extra safety margin by avoiding consequential terrain above rocks, cliffs and trees, or features that will collect avalanche debris and pile it up deep. Be diligent with safe travel protocol by only exposing one person at a time to steep terrain, and watching your partners from safe locations out of the potential avalanche path and runout zones. These problems are not easy to deal with, and now is not a great time to be pushing the needle into big terrain.

Poor stability test results on a layer of buried facets from a test pit on Raggedtop yesterday.