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Avalanche: Turnagain

Location: Tincan Common

Date:
Observer:
Route & General Observations

Toured the standard route to Tincan Common up-track. As we started up above treeline we noticed a snowpack change due to the wind effect from moderate sustained SW winds Thursday night into Friday. As we crested the first hill above treeline we ran into a party that had witnessed a skier triggered avalanche in Common Bowl. The skier was caught carried and lost a ski. That party also triggered the rolls riding back down the ski track. See more on this below.

Avalanche Details
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Trigger SkierAvalanche Type Soft Slab
Aspect SouthwestElevation 3000ft
Slope Angle 30degCrown Depth 10in
Width 100ftVertical Run 300ft
Avalanche Details

5+ Skier and snowboard triggered sensitive soft slabs that were fast moving and widely propagating in areas that had some wind effect above 2500'. Some of the crowns were on lower angle terrain, 18-15 degree slopes. Note: surface hoar is notorious for lower angle avalanches and wide propagation. The slab and the bed surface were both soft (4F) while the layer of buried surface hoar was just slightly softer. The avalanches were fast moving and a couple ran into the steep terrain below down towards Tincan Creek. One was large enough to knock a skier over and he lost his ski and pole.

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)?Yes
Observer Comments

Recent avalanches, cracking and remote triggering (propagation), recent snow, recent wind loading, another party in the area reported whumpfing on the way to the ridge
No cracking or whumpfing observed below 2500'.

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

Overcast to obscured skies
Light snow on and off throughout the day
NE winds 10-20 mph gusting into the 30 later in the day

Snow surface

1000'-1500'- 6-8" of new snow on a melt freeze crust, open creeks and swampy patches
1500'-2000' - 8-10" of new snow over 5 inches of moist melt freeze grains
2000-2500' - 10" of new over 15-20" of older snow on moist melt freeze grains
2500'-3000' 10-15" of wind effected, new snow over 2-4 feet of older rounded snow/mixed with melt freeze crusts

Snowpack

See pit photo and avalanche photos. HS: 150 cm, HN: 30 cm. Notable 1 cm surface hoar buried below 10-15" of new snow. Smaller buried surface hoar found @ 1800' non-reactive.

Photos & Video
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