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Observation: Turnagain

Location: Tincan

Date:
Observer:
Route & General Observations

Toured to ~3300′ to see how well the 1/26 snow was bonding to the old snow and to see if we could find any locations where the 1/26 snow was forming a slab.

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?Yes
Collapsing (Whumphing)?No
Cracking (Shooting cracks)?No
Observer Comments

Small slab avalanche in God's Country on Seattle Ridge, possibly remote triggered over the weekend. There are nearby tracks on the ridge. Small natural soft slab below CFR that looked to be triggered by cornice fall/recent wind loading overnight (see photo below). See separate road observation for photos of Seattle Ridge.

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

-1F at the Tincan pullout at 1145, 4F at 1630. Noticeable inversion (sweating in the sun!). Bask-worthy sunshine up high. Wind calm to light from the north.

Snow surface

The 1/26 snow has settled quite a bit, but is still quite deep for skiing and skinning. 5mm+ surface hoar observed at all elevations, except near ridgelines where it has been knocked over by wind. Surface snow was still very soft, we found little or no wind effect except within +/- 100 ft of CFR ridge, where it has been more scoured on Northerly aspects and loaded on Southerly aspects. Ski tracks in Hippie Bowl were partially filled in from the wind.

Snowpack

The 1/26 snow appears to bonding well to the old snow, as indicated by many hand pits where it was impossible to initiate a planar failure as no slab existed. The surface snow was only remotely cohesive or slab-like in limited areas, i.e., leeward features. In these areas pole probing, unpleasant ski turns, and visual clues of the wind affect were indicators of the slab formation.

Dug two test pits at ~3300 ft, SW aspect (Skiers left of the ridge that separates Common Bowl from Hippie Bowl):

Pit 1: Intentionally dug in a wind loaded area where the surface was obvious wind slab, to see if we could still find the 1/21 BSH, and if it was reactive. HS=210cm. TD=100cm. Found 1/21 BSH below 50cm of 1F wind slab. 1F+ wind slab to 100cm below BSH. Was able to get moderate CT failures in wind slab density changes above the BSH, but CTNx3 on the BSH. ECTN15 down 25 on stellars between wind slabs, ECTX on BSH. PST 40/100 END down 50 on BSH.

Pit 2: Intentionally dug in a wind loaded area, about 20 feet below Pit 1. This location had more of a thin wind crust instead of a wind slab, and contained the Jan. 21 BSH intact about a foot down. Results: CTN, ECTX, shovel shear moderate and easy on the Jan. 21 BSH layer. The thin wind crust was about 1/2" thick and contained 4F hard snow beneath.

Photos & Video
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