Avalanche: Turnagain

Location: Tincan Trees

Date:
Observer:
Route & General Observations

Tincan to treeline

Avalanche Details
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Trigger SkierAvalanche Type Soft Slab
Aspect NorthwestElevation 2000ft
Slope Angle 38degCrown Depth 20in
Width 50ftVertical Run 50ft
Avalanche Details

Multiple skier triggered and a few natural soft slab avalanches below and at treeline today in Tincan Trees, mainly D1-1.5s on steep rollovers, though some folks spoke of larger ones more to the north of where we skied (we stuck to the skin track route). These ran on buried facets/surface hoar that was covered by new snow in the past 24 hours. Slide depth was = to storm depth of ~16-20", with some variation due to wind transport. See photos below for examples. At least two naturals at or below treeline as well, which appeared to have run this AM as they were only covered by a few inches of snow.

Other than some sluffing off the steeps of CFR ridge, NO natural avalanche activity observed above treeline, with a mid-day broken skies giving a good look at the north aspect of sunburst, common, and sunnyside as well.

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

On top of recent avalanche activity, whumphing was frequent above 1500' whenever stepping off the skin track. Whumphs were of two qualities - many quieter ones that seemed more localized. At treeline near the beaded stream station, one whumph sounded deeper, and seemed to travel 100+ yards.

Cracking occurred on slopes as low angle as in the high-20s, as well as on slopes in the 30s that did not slide.

Weather & Snow Characteristics
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Weather

SNOW! Almost 1"/hr in the AM, slowing down and broken skies by 1 PM.
Storm Totals: @ 1000' - 16" of new! (12" of moist topped with 4" of dry snow)
1500 to 2000' - 20" of new dry snow from this storm, with some variation of depth due to wind affect
Temps in the 20's - low 30s, light occasional winds from the north midday.

Snow surface

Lots of soft snow, with ski penetration of 12 - 16" above 1500'

Snowpack

Two quick pits/profiles were dug at sites of slides:

Pit #1 Crown Profile (triggered this roll from above, see photo below)
2000', NW aspect, 38 degrees, HS=130
surface -> down 90cm: Fist to 1 finger hard new snow
(wind loaded location) over 4 finger buried facets to the ground

Pit #2 Test Results (adjacent to skier triggered D1.5, see photo below)
2200', NW, 20 degrees, HS=100cm
CT 12, 15 SP and ECTN 7 down 50cm in BSH
*failure also occurred at CT 27 SC below the crust, but the test had destroyed nearly all the block at this point
Surface -> down 50cm: Fist to 1 finger hard new snow
@ 50cm down: Buried Surface Hoar
50cm - 85cm down: 4 finger facets
85cm - ground: first hard facets w/ thin melt freeze crust in the middle of layer

Photos & Video
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