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Many signs of Instability Castle Peak

Location Name: Castle Peak Region: Donner Summit Area Observation Date & Time: Saturday, December 1, 2018 - 07:45
Location: 39.344819, -120.349765 See map: CalTopo	Is this an Avalanche Observation?: Yes Conditions Alerts: Avalanche Activity Other Signs of Instability (cracking, whumpfing, collapsing) Other Signs of Instability (cracking, whumpfing, collapsing)›Shooting Cracks Recent Loading Recent Loading›Blowing Snow Recent Loading›Snowfall Rates of More Than 1 in/hr Terrain Alerts: Slopes Steeper than 30 degrees Terrain Matches the Advisory

Observation made by: Public

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Observation

Description of Snow, Weather, and Avalanche Conditions:

Touring around Castle Peak our party stayed in below treeline and near treeline terrain. We saw mulitple signs of instability below & near treeline including shooting cracks from skis, test slopes failing in the new storm snow, and we saw the crown from a natural slide. The small windslab slide occured on the northeast aspect of a large boulder in below treeline terrain.

Avalanche Details

Avalanche Type:

Wind Slab

Failure Plane/Weak Layer:

New/old snow interface

Trigger

Trigger:

Natural

Terrain

Start Zone Slope Angle:

38degrees

Aspect:

Northeast

Starting Elevation:

below-treeline

Size

Destructive Size:

D1 Relatively harmless to people.

Relative Size:

R1 Very Small

Crown Height:

1 ft

Avalanche Width (Average width):

10ft.

Avalanche Length (Vertical Run):

20ft.

Weather Details

Elevation of Observation:

7000 - 8000 ft.

Blowing Snow:

Moderate

Wind Direction:

Southwest

Wind Speed:

Moderate

Sky Cover:

Overcast - Cloudy - 8/8 covered

Highest Precipitation Rate:

Moderate Snowfall (S2 = 2 cm /~1 in per hour)

Precipitation:

Snow

Air temperature:

Below Freezing

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Many signs of Instability Castle Peak

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Many signs of Instability Castle Peak

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