Turnagain Pass

As mentioned in the Bottom Line, there was an avalanche triggered along the Crow Pass summer hiking trail yesterday. A backcountry rescue response was initiated and all parties were located and ok. We will update this link with details as they become available.

One more clear sky day and cold temperatures are in store before clouds head in along with some snow flurries possible tomorrow. The snowpack remains in its holding pattern of sorts with various weak layers sitting 1-3′ below the surface, possibly deeper, while the surface snow continues to loosen and facet in many zones.

What this means for us today is the possibility of triggering a slab avalanche needs to remain on our radar. Although we don’t have details on yesterday’s avalanche yet, this only highlights that dangerous slab avalanches are still possible to trigger. Generally speaking, there are faceted weak layers and a layer of buried surface hoar that are responsible for not allowing the snowpack to completely stabilize. We’ve found these layers mostly 1-3 feet deep and showing signs that they are becoming harder to trigger with time. This is a tricky problem because the snowpack might ‘seem’ stable even if it is not. Signs of instability are not usually present before a slope releases in this case and many tracks can be on a slope before someone hits just the wrong spot. Thin areas in the snowpack are the most likely places to trigger a slide, they are often near rocks and on top of rollovers. Watching our partners, exposing only one person a time and being aware of consequences if the slope does slide are all good ways to help stack the odds in our favor.

Light to moderate northwesterly winds have been over the region for the past several days and bumped up into the moderate range yesterday morning. Although much of Turnagain Pass has been spared the wind, other areas such as the Girdwood Valley and Portage Valley have seen just enough wind to transport snow along the higher peaks, as can be seen in the photo below.

Winds have quieted down to 5-10mph, where they are expected to remain through the day. Due to the light winds, fresh wind slabs are not likely to form. However, finding and triggering an older wind slab is possible. These slabs could be sitting on weak faceted snow, which can make them easier to trigger. Watch for areas that have been loaded by the winds, these often have a smooth rounded shape. Also feel for stiffer snow over softer snow, hollow feeling snow and cracking around you in the snow surface. These are all signs of a wind slab.

Wind transport along the higher terrain on Goat Mountain in the Girdwood Valley yesterday morning. 1.10.20.

Loose snow sluffs:  On slopes out of the wind the surface snow is becoming looser and looser by the day with the cold temperatures. Sluffs are getting larger because of this and gaining volume in longer sustained slopes. Watch your sluff.

Despite the very cold temperatures, glide cracks continue to slowly open in certain areas around the region. Although none have released into avalanches for several weeks that we know of, it is still wise to limit exposure under them as they are unpredictable and could release at anytime.

Glide cracks that are oozing open in the Peterson Drainage. 1.10.20. Photo: Turner Pahl

Close up of cracks and how the snowpack is buckling as gravity pulls it down the slope in slow motion. 1.10.20. Photo: Turner Pahl

Cornices:  Cornices are looming along ridges. As always, be sure to give them plenty of space and limit your exposure when passing beneath them.