Loose Dry on Andesite

Location Name: Andesite Peak Region: Donner Summit Area Observation Date & Time: Sunday, March 1, 2020 - 11:45
Location: 39.350746, -120.367533 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›More Than a Foot of New Snow Terrain Alerts: Slopes Steeper than 30 degrees Trigger Points Terrain Traps Terrain Matches the Advisory

Location Name:

Andesite Peak

Region:

Donner Summit Area

Observation Date & Time:

Sunday, March 1, 2020 - 11:45

Location:

39.350746, -120.367533

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›More Than a Foot of New Snow

Terrain Alerts:

Slopes Steeper than 30 degrees

Trigger Points

Terrain Traps

Terrain Matches the Advisory

Observation made by: Forecaster

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Observation

Description of Snow, Weather, and Avalanche Conditions:

A ski kick above a steep rollover pushed snow onto the steeper slope where it entrained the storm snow. The resulting loose dry avalanche continued downhill sliding into less steep terrain where it stopped. The sliding snow did pick up some speed as it moved downhill and could have knocked a person over. It did not involve enough snow to bury a person. This loose dry avalanche occurred on a slope that was more sheltered from the intense NE winds.

Loose dry avalanche on a steep slope sheltered from the wind that entrained the new snow

Avalanche Details

Avalanche Type:

Loose Dry/ Sluff

Failure Plane/Weak Layer:

Storm Snow

Trigger

Trigger:

Snowboarder

Trigger Modifier:

Intentionally Triggered

Terrain

Start Zone Slope Angle:

40degrees

Aspect:

West

Starting Elevation:

below-treeline

Size

Destructive Size:

D1 Relatively harmless to people.

Relative Size:

R1 Very Small

Crown Height:

Less than 1 ft

Avalanche Width (Average width):

6ft.

Avalanche Length (Vertical Run):

40ft.

Weather Details

Elevation of Observation:

6000-7000 ft.

7000 - 8000 ft.

Blowing Snow:

Intense

Wind Direction:

Northeast

Wind Speed:

Strong

Sky Cover:

Overcast - Cloudy - 8/8 covered

Precipitation:

Snow

Air temperature:

Below Freezing

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Loose Dry on Andesite

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Loose Dry on Andesite

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