Cracked Ice

Decided to go up Cracked Ice to try to target the 1/26 BSH layer and whether warm temps have decomposed the layer or not.  Dug at 2500' on a north aspect where this layer is expected to be most prevelant.  Found the layer in question to be well intact but no propagation in ECT or PST.  ECTN11 down 35 cms and PST SF (28/100).  Both of these scores indicated that a problem existed, but the slab was still not cohesive enough in this location to be sensitive.  Problem was stubborn.  A couple of small natural avalanches were observed on the Python buttress at a similar elevation that appeared to have happened in the last 36 hours.  There was a thin rain crust at the surface up to 2600'.

Above 3000', where surface hoar had not been observed prior to new snow we found an upper snowpack that had no wind effect at the surface, hand shears ranged from moderate to hard and pole probing showed a right side up snowpack.  In other words we had no signs of instability or cause for concern.  We skinned to the summit ridge on cracked ice which has a short slope that exceeds 40° for a short portion.  We continued to find no signs of instability, and a right side up snowpack.  

We skied skiers right at the top into a slightly steeper slope probably 37° (prime avalanche terrain).  I skied first off the top to a spot where I could watch Skier 2 go down the steeper roll (~400 vertical feet). Skier 2 skied first down the slope without incident and stopped at the bottom to watch.  I followed and triggered a D2.5 avalanche immediately when I rolled onto the slope.  I straight lined through the slab, when I hit the stauchwall. (bottom fracture of the avalanche) I was overtaken by the flow and enveloped.  I fought hard and pulled my air bag which deployed, but did not inflate.  when the slide came to a stop I was fully buried with snow packed in my airway.  I cleared snow from my face as the slide stopped and worked my hand upward and found that i could raise my arm out of the snow and was shallowly buried.  I worked snow from my face with my one free hand and was dug out by my partner.  I was very lucky and had no injuries

Slab avalanche was on a slope that could be loaded by north wind, however snow was unaffected by wind and long fracture character indicated a faceted grain at the interface.  We have been talking about surface hoar below 3000' as a concern, but it is now clear that there is faceted snow at the interface of the new snow that has fallen since 1/26 at upper elevations as well.  The previous week of clear weather from 1/26 is an issue at upper elevations as well as below 3000' where large buried surface hoar exists.

Triggered a D2.5 avalanche on a W/NW aspect was caught, carried, and fully buried. Crown width estimated at 500'/depth 2'. ARu-SS-R4-D2.5