The Evolution of the 2014 'Damalanche' Facet Layer in South-Central and SouthEast Alaska

The 2014 mid to late season snowpack in the Eastern Chugach Range of Alaska presented challenges and learning for the heli-ski operations around Thompson Pass, and in the bigger picture the entire Chugach Range and mountains of SE Alaska. The rain event that triggered the widespread avalanche cycle on January 24 and 25, 2014 was known as the “Damalanche” cycle for the Dam that it created on the Lowe River at the mouth of Keystone Canyon. This event, by itself, was not a serious problem further into the winter, but the saturated snowpack that resulted fostered the growth of near-surface facets (via melt-layer recrystallization or “DW faceting”) that grew to the size of 5mm depth hoar grains in ‘favored’ locations. This layer, dubbed the “Damalanche Facets” went through a fascinating period of building, dormancy, activity, dormancy and reactivation. A similar layer formed in SE Alaska and some of the similarities will be addressed. Through more than two months of direct observation we saw varying degrees of strength, propagation and friction; universally poor structure; and widespread continuity of the weak layer. This paper addresses the formation and evolution of the dam facets, lessons learned for forecasting and guiding, and thoughts for tracking similar layers into the future.