Avalanche: Turnagain

Location: Cornbiscuit Avalanche Investigation

Date:
Observer:
Route & General Observations

We investigated the avalanche on Cornbisuit, collecting some data to fill in the gaps. Thank you to all of the groups involved for sharing so much info already. This observation has some of the more technical information. We will be publishing a full near-miss report within the next few days. In addition to the information in this observation, we have already posted multiple observations shared by the groups involved with firsthand accounts of the details leading to and following the event.

Avalanche Details
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Trigger SkierRemote Trigger No
Avalanche Type Hard SlabAspect Southwest
Elevation 2800ftSlope Angle 37deg
Crown Depth3ftWidth 900ft
Vertical Run 1000ft  
Avalanche Details

Crown height: 2.5-4' (80-120 cm). Deeper pockets were close to 6' deep.
Average width: 900'
Vertical fall: 1000'
Weak Layer: Facets between two crusts.
Crown elevation: 2800'
Aspect: SW
Start zone slope: 37 degrees
Alpha angle: 27 degrees

HS-ASu-R3-D3-O

The avalanche failed on a fist-hard layer of facets sandwiched between two melt-freeze crusts. This would be just below the uppermost crust of the Thanksgiving crust/facet layer. The avalanche also pulled out several pockets down to the ground as it ran. We found fist-hard 2mm facets on the ground at the crown. We did a quick ECT at the crown and got an ECTPV, with the column popping right out of the pit, failing on the same layer that the avalanche failed on.

Weather & Snow Characteristics
Please provide details to help us determine the weather and snowpack during the time this observation took place.
Weather

Mostly cloudy, with an inversion. Cold in the parking lot (-6F), felt like high teens to low 20's F later in the day. Not a breath of wind, increasing clouds through the day.

Snow surface

Surface hoar up to the ridge, sitting on a layer of faceting powder. Great skiing now, not going to be so great when it gets buried...

Snowpack

See details in photos and avalanche sections.

Photos & Video
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