Turnagain Pass

No new natural avalanches were seen or reported yesterday. Also, few folks were out in the backcountry yesterday and to our knowledge, people have stayed out of avalanche terrain and slopes have not been tested. However, artillery was able to trigger large slabs during AKDOT & PF’s avalanche hazard reduction work along the Seward Highway. Below are few more photos of the natural avalanche cycle that occurred Tuesday through Thursday (Feb 18-20).

A zoomed in look into Davis creek (between Magnum and Cornbiscuit) and the Superbowl area with Goldpan peak in the far distance. Note the multiple slab avalanches. These most likely released Wednesday night or very early Thursday morning (Feb 19 or 20). Photo taken on Feb 20 by Travis Smith.

Natural slab avalanche on Sunburst’s SW face. Note the debris further up valley in the shade. It appears that earlier in the storm a few additional sections of Sunburst avalanched as well. 2.20.20. Photo: Travis Smith

Various pockets of slab avalanches that occurred on Cornbiscuit’s west face. 2.20.20. Photo: Travis Smith

With a clearing trend on the door step and 6-8″ of new snow from yesterday (on top of the 3-5 feet of new snow from Tues-Thur), the mountains will be quite enticing to powder lovers for the next few days. This is worrisome. Not only because the storm snow is still adjusting, but under all that amazing snow are weak layers that are proving to be reactive.

The natural cycle we had a glimpse of Thursday afternoon proves that the snowpack isn’t stable. Many of the avalanches had crowns 5-8′ thick, were rated ‘very large’ and stepped down into buried weak snow. Can someone charge up and onto slopes and trigger one of these monsters? Can a person be cautious traveling along a ridge and trigger one? What about triggering from below a slope? Everything we have seen so far points to YES, we can. We are in a ‘tip-toe’ situation because these types of avalanches are much too large to have any way of managing.

To avoid these issues, we can play in the powder in the flats or on slopes 30 degrees or less with nothing steeper above us.

If you are headed out into avalanche terrain today, things to remember:

• Between 3-6′ below your snowmachine or feet sits various layers of weak sugary faceted snow
• Very large avalanches could be triggered that take out the entire slope
• Yes, many slopes have already slid, but these could have portions still intact and waiting for a trigger
• There is no way to know how close a slope is to avalanching. It could be the first person or the 15th person that hits the trigger point.
• Remote triggering is possible (initiating a collapse in the weak layer from the top, side or bottom on the slope resulting in an avalanche)

The photo above shows the weak facets around 3 feet deep. The image also shows a failure in the slab from a storm snow interface that is still bonding. Either way, unfortunately there is bad news in our snowpack.

Close up view of the Motorized up-track on Seattle Ridge and a portion of the Repeat Offender slide path has not slid. Another big thanks to Travis Smith for his photos.

Video Link HERE.

Storm snow avalanche issues exist in the top couple feet of the snowpack. Keep in mind, one of these types of avalanches could ‘step down’ and trigger a much larger slide.

Wind slabs:  The wind picked up last night, blowing 15-20mph with gusts near 40mph from the east. With all this fresh snow, we can expect to find new touchy wind slabs around a foot thick. Additionally, older wind slabs from last week’s storm could be triggered, these would be several feet thick and very dangerous.

Storm slabs:  The storm snow from the past week is still bonding to the old snow underneath. Triggering a slab composed of the storm snow is still possible. The snow has settled just over a foot and these storm slabs are now in the 1-3′ thick range.

Cornices:  These have grown substantially over the past week and could easily be triggered. If making it to the ridgelines, be sure to give these features a very wide berth.

Loose Snow avalanches:  Sluffs in the loose surface snow are likely. If getting on slopes this steep, there are much larger avalanche problems to deal with.