Professional Observer:   Kevin Wright

Location:   Turnagain   -   Tincan

Date:   Dec 9th, 2012

Sunday was an interesting day to be in the mountains. Not much natural avalanche activity was
obvious, but any steep roll above treeline wanted to slide. We got half a dozen slabs to move
with ski cuts, staying in lower consequence terrain features.

Pit data showed a very loose layer of new snow ~10 inches below treeline where wind did not
affect it. Despite having almost no stiffness, this layer would break on the old weak layer
(surface facets and buried surface hoar). ECTP 6 Sudden Collapse Q1

Above treeline the new snow was either scoured clean on the windward side or piled deep on
the leeward side. Wind slabs were over 2 feet deep at the ridgetops, 1 finger to pencil hard,
and showed a hard slab reaction to ski cuts (supported the skier until it broke above them).
The very weak facets at the new snow/old snow interface were again the interface where the
slab broke.

Photo 1. Small roll just above treeline, storm snow avalanche, skier triggered
Photo 2. Tincan ridge, skier triggered, over 2 feet deep windslab
Lat: 60.7872 Long: -149.1631


Professional observers are employees of organizations specializing in avalanche forecasting, mitigation and/or education. Some examples include: CNFAIC staff, AKDOT and AKRR avalanche program employees, AAS/AAI/AIARE level 2 and above avalanche instructors.

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