Avalanche: Turnagain

Location: Cornbiscuit @ treeline

Route & General Observations

Alaska Pacific University Snow Science 1 class toured in storm conditions to observe how the new snow is bonding with old snow surface.

Avalanche Details
If this is an avalanche observation, click yes below and fill in the form as best as you can. If people were involved, please provide details.
Trigger NaturalRemote Trigger0
Avalanche Type UnknownAspect Unknown
ElevationunknownSlope Angleunknown
Crown DepthunknownWidthunknown
Vertical Rununknown  
Avalanche Details

On the way down to the pass, we happened to observe a natural avalanche running down to Turnagain Arm. This path is directly across the water from Girdwood Tesoro, off the peak 3849. The starting zone was in the clouds, so we have not that much data on avalanche specifics. There was no dirt in the new debris piling up & powder cloud was significant.

Red Flags
Red flags are simple visual clues that are a sign of potential avalanche danger. Please record any sign of red flags below.
Obvious signs of instability
Recent Avalanches?No
Collapsing (Whumphing)?No
Cracking (Shooting cracks)?Yes
Observer Comments

Only localized cracking within new storm snow.

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

It snowed on us most of the day in the afternoon reaching rate up to 2 cm/hr. It was nice to see big fat flakes!
Visibility was poor most of the day so we ended up turning around at 2000'.
Temperature was hovering below freezing. North wind was moderate & making the snow move horizontally in the air.

Snow surface

Moist new snow on the surface, 5-10 cm depending on elevation. Old snow surface was quite supportable. At 2000', surface snow started feeling more windpacked, but we did not reach any ridgelines to assess full wind impact.
We observed small roller balls on steeper slopes below our skin track - makes sense with the moist, warm, storm snow.


Hand shear test showed some cohesiveness within the new storm snow. Small test slopes did not show expected storm slab releases, but this could be different on steeper (>35) slopes.
We were tracking several crusts within the top 50 cm of the snowpack with poletests on our skin up.

We dug a test pit at 2000' on a 28deg NW facing slope just above the last tree island. HS 265cm.
While snowpack seemed stable, we did get interesting results that concentrated below crust 65 cm below the surface. Upon taking a closer look, we found some faceted forms below the knife hard crust that kept acting as a layer of concern on all of our tests
Test results (all on the same layer): CT17RP, CT20RP, ECTP31RP, ECTP w Boot Crusher, PST64/100RP.

Photos & Video
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