February 11, 2018

Avalanche Danger Update

Avalanche danger has increased due to wind loading that began late last week.  Avalanche danger is expected to increase further through Monday due to strong winds and the potential for a few to several inches of new snow.

The snowpack is generally very thin to non-existent below 2500′, and relatively thin in the upper elevations.  The snowpack, in general, is extremely weak and has very poor structure (basically a pile of varied facets with very large depth hoar at the ground).

Areas where dense, supportable wind slabs exist seem to be the “sketchiest,” and large whumphs and collapses were experienced in such areas middle of last week despite an extended period without significant weather.  Persistent slab danger exists, and will be exacerbated by additional stress from wind loading and new snow through Monday.

As of Saturday, fresh wind slabs were forming and reactive to human triggers down to ~2000′ elevation in some areas (Turnagain Arm) due to ample loose snow available for transport.  On Thursday, several pockets of reactive D1-D1.5 wind slabs were found along the Peak 3-4 ridge.  On Wednesday, large whumphs and collapses on buried persistent weak layers overlain by stout windboard were experienced on bigger terrain in the Arctic Valley backcountry.

Strong winds and new snow will stress the numerous and widespread existing instabilities, and create new instabilities in the form of even more widespread wind slabs through Monday.

Riding conditions have been variable, and Chugach State Park is rife with thin snowpack hazards (exposed or shallowly buried rocks, vegetation, etc).

Make sure you’re checking the AAC social media (Instagram and Facebook) for the latest updates.