Avalanche: Hatcher Pass

Location: Arkose Ridge, Mile 10, south side of the Little Su

Date:
Observer:
Allie Barker Forecaster
Route & General Observations

Observed a skier triggered avalanche at approximately 2:30 pm today. We saw the powder cloud from Marmot and were able to watch the skier descend safely down the ridge. Skier performed a ski cut which resulted in a large avalanche ,SS-ASc-D2.5-I on a SW aspect . This avalanche wrapped the ridge to a NE aspect and stepped down into old weak facets. The majority of the slab failed on facets on the sun/drizzle crust.

Avalanche Details
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Trigger SkierRemote Trigger No
Avalanche Type Soft SlabAspect Southwest
Elevation 3800ftSlope Angleunknown
Crown Depth 12inWidth 500ft
Vertical Run 2000ft  
Avalanche Details

Observed skier triggered avalanche while performing a ski cut. The avalanche wrapped the ridge from SW to NE approx 500 ft wide and ran approx 2000'. The avalanche failed on facets on the sun crust/drizzle crust and stepped down into older weaker facets and depth hoar in specific locations. The powder cloud could been seen from the top of Marmot.

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)?No
Observer Comments

Whumping felt on uptrack on SW ridge of Marmot today. Instability tests clearly showed propagation and slab failing in facets on sun crust/drizzle crust layer at 125 cm in the snowpack. Recent remotely triggered avalanche on punk spines 4/1 (see obs) and another human triggered near miss on the exit of gold chord lake 4/2(see obs).

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

No new snow today.
Significant warm up today, felt hot on the skin track. Intense solar radiation today.
Temps reported at IM averaged 15deg F but felt like Hawaii.

Snow surface

2-4" thick stout sun crusts on southerlies and westerly today. By 11:30 am crusts had softened on southerlies but not west aspects. Rimed stellars and graupel was observed on the surface.

Snowpack

4200' W aspect 34deg slope
CT 13 SP
CT 14 SP
ECTX
PST 20/100 end
*All tests failed in facets on sun crust/drizzle crust at 125 cm (50"), approx 60 cm deep (24")
This is the culprit weak layer from all the recent avalanches this week.

Photos & Video
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Powdercloud from avalanche  

Large human triggered avalanche that wrapped the ridge from SW to NE and stepped down into old facets and depth hoar.  

Large human triggered avalanche that wrapped the ridge from SW to NE  

Location
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