BC Zone Observation Report
Friday, December 9, 2016 at 12:00 AM
Crested Butte Area
Snodgrass Mtn, NE aspects. 9,400-10,600 ft.
Overcast, S-1, calm winds below treeline with a few plumes and gusts observed up high, mild temps.
Below treeline, the structure remains shallow and faceted, but we are starting to see signs of instability with the new snow. A few shooting cracks and one collapse observed today on NE aspects below treeline. There is about 6-8" very soft slab over the Dec 6th near surface facet layer (1mm, F hard), with facets to the ground below that. In a few areas, there is some lingering 4F midpack, faceting slab, and we got one collapse where this was overlying ~2mm basal facets. This seemed to be a fairly isolated concern where we traveled, and saw no other signs of instability on various slopes up to 40 degrees in steepness. My biggest concern is when we put a real slab on our Dec 6th facet layer, which was widespread across every slope we traveled on.
We skier triggered one small soft slab, failing on Dec 6th facet layer, about 8" thick and 25 feet wide. Harmless in size, and managed like a storm slab. SS-ASc-R1-D1-I
AS / c
O - Within Old Snow
Failing on Dec 6th facet layer
12/9/16 Signs of Instability Below Treeline