Turnagain Pass

The potential for skiers, riders and snowmachiners to trigger avalanches within layers of the new snow is very high today.  Terrain above treeline harbors large areas of slab, including wind slabs, that will be very sensitive to human triggers.  The steady and often rapid loading of this week has created unstable conditions in the upper layers of the snowpack.  Those of you who have ventured out into the mountains this week have witnessed this firsthand, getting machines stuck in the weak snow and enduring arduous trail breaking.  This new snow is dense and unsupported in many areas, making travel slow and challenging.  Below 1000 feet we have wet snow due to rain falling over the past 24 hours.  It all boils down to the fact that we have a lot of new snow sitting on multiple weak layers.  While we have limited info from the upper elevations, we know that the snow is very unstable, as both AKDOT & Alyeska resort have been able to trigger avalanches on a variety of aspects and elevations.  Large natural avalanches as recent as yesterday morning have been observed in the region.  The recent observations from the backcountry that we do have paint the picture of instability well.

While deep slabs are a secondary concern to storm snow/wind slabs, do not underestimate the potential destructive force of this type of problem.  Large, dense slabs that have formed over the past four days sit on a base of weak snow.  Triggering avalanches that break into these deeper layers could have dire consequences.  If caught in a deep slab avalanche, the chances of surviving are low.  I like to think of this problem as one that is unmanageable.  As such, it is important to keep terrain choices very conservative.  An avalanche triggered even in seemingly “small” terrain could have serious consequences given the large volume of snow.  While storm snow instabilities will diminish within days of the end of a storm, this deep slab problem will be with us for an extended period of time.