Avalanche: Turnagain

Location: Seattle Ridge

Date:
Observer:
Route & General Observations

Approached TT43 from Cornbiscuit lot. Crossed the bridge and headed up a scoured ridge to 3500′. Descended a leeward ridge just north of our uptrack.

Avalanche Details
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Trigger SkierAvalanche Type Hard Slab
Aspect SoutheastElevation 2800ft
Slope AngleunknownCrown Depth 6in
Width 20ftVertical Run 300ft
Avalanche Details

While descending a leeward ridge, my ski partner made several hard turns while traversing a windloaded slope. He was able to trigger two windslabs, both initiated from his sluff and stepped down, further down the slope. The debris combined and ran into a steep gully/slide path.

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)?Yes
Cracking (Shooting cracks)?Yes
Observer Comments

Near the top of the ascend ridge I walked onto a steep wind slab. The slab fractured and failed, but only shifted ~1" due to the terrain feature. The cracks propagated south out of sight roughly 150' into a steeper slope. We did not see any signs on a slide, from the ridge or the road. The pin on the map indicates the location of this event.

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

Very cold in the valley. Slightly less cold at elevation in the sun. Snow transport visible on Pastoral and the peaks above Lynx Creek. Miserable west wind on the bench at 3500' between TT43 and New World.

Snow surface

Impressive surface hoar in the valley. Very light sugary snow on crust up to ~2100'. Most snow was wind affected above alder line.

Snowpack

We investigated the snowpack at the site of the large shooting crack.
Pit location: 3500' SE
HS 80cm
Slab depth ranged from 30-45cm of Pencil to 1F wind deposited snow
The weak layer was 10cm of 4F facets sitting on Pencil hard snow

No formal stability test.

Photos & Video
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