Observation: Turnagain

Route:
Travel was from 900′ to 2,800′ on the West Sunburst ridge.

Weather:
Clouds and visibility were in and out with occasional snow squalls. Only a trace of accumulation. Temperature was in the 15-20F range and wind was calm.

Signs of instability:
Recent avalanches – No
Collapsing – Yes, one medium – but dramatic – collapse (30-40′ radius). This was initiated with boot penetration. Collapsing layer was either basal facets or facets above/below Dec drizzle crust. We dug our pit, detailed below, at this site.
Cracking – No

Snow Surface Conditions:
900-1500 – crusty
1500-1800 – thin 2mm soft crust below 2-3″ of low density snow
1800-2800 – 4-6″ low density snow over gradually harder snow

Snowpack Observations:
One pit at 2200′, West facing, 24 degrees (site of collapse)
ECTP 14 Sudden Collapse failing on facets above the Dec driz crust down 75cm
CTV (on isolation) Sudden Collapse – same failure layer as ECT
CT 7 Sudden Collapse – failed simultaneously above the drizzle crust and in the basal facets
PST 37/100 (end) down 75cm

*This is the first time in a week that I have seen the weakest layer in a pit located above the Dec drizzle crust. This ‘was’ the weakest layer 2 weeks ago but during the past week or more we have seen the crust bonding with the slab above. Also during this time we have seen a transition with the weakest layer becoming the facets below the drizzle crust and after that trending to the basal facets. This pit was definitely interesting. But, in the big picture we have weak snow near the ground – just several different layers to choose from….

On another note – we did not see any people stepping up the slope angles today – however, visibility was limited.