Avalanche: Turnagain

Location: Lynx Creek

Date:
Observer:
Route & General Observations

We observed a number of older natural avalanches. The avalanches where both point-release and around 2′ deep soft slabs. We are fairly certain that the soft slabs initiated on the buried surface hoar that has been causing us trouble for over a week. We observed these avalanche on mostly on south, north, west facing slopes with >35˚ slope angles.

 

Avalanche Details
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Trigger NaturalRemote Trigger Unknown
Avalanche Type Soft SlabAspect South
Elevation 3000ftSlope Angleunknown
Crown DepthunknownWidthunknown
Vertical Rununknown  
Avalanche Details

There where two types of older avalanches. One was the wet-loose point release avalanches running around size D1.5 -2 for the warm weather event on Tuesday. These could have been some triggers in the slab avalanches releasing on the buried surface hoar. We dug a pit at 2000' on a low angle north facing slope to test the reactivity of the BSH. Our ECT test provided no results and it took prying on the snow above to initiate a shear release.

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

Andrew was able to get shooting cracks (2 feet deep) while riding a small slope at 3,000'. Big red flag for the buried surface hoar reactivity.

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

Weather: Scattered clouds throughout the day with temperatures in the 20s˚ at mid elevations.
No wind in the drainage.

Snow surface

There was a breakable crust at the trailhead that eventually became thinner, then went away around 2000'. The snow was drier at with soft settled powder above 2,000',providing great riding.

Snowpack

Snow depth in our north pit at 2000' was 6 ft deep and the BSH layer was 2' deep and did not react during our stability test. We did not dig to the Christmas or Thanksgiving crust though we where able to feel them with our probes at 3.0' and 4.5' deep respectively.

Andrew did a pit at 3,000' and had an ECTP 14, this is near the shooting cracks he initiated. Clearly the snowpack was more reactive there than our lower pit at 2,000'.

Photos & Video
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