Sensitive wind slabs on Powderhouse

Location Name: Powderhouse Region: Luther Pass Area (including Job and Freel) Observation Date & Time: Wednesday, March 25, 2020 - 09:00
Location: 38.782750, -119.979791 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 Recent Loading›Snowfall Rates of More Than 1 in/hr Terrain Alerts: Slopes Steeper than 30 degrees Trigger Points Terrain Traps Terrain Matches the Advisory

Location Name:

Powderhouse

Region:

Luther Pass Area (including Job and Freel)

Observation Date & Time:

Wednesday, March 25, 2020 - 09:00

Location:

38.782750, -119.979791

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
Recent Loading›Snowfall Rates of More Than 1 in/hr

Terrain Alerts:

Slopes Steeper than 30 degrees

Trigger Points

Terrain Traps

Terrain Matches the Advisory

Observation made by: Public

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Observation

Description of Snow, Weather, and Avalanche Conditions:

We found 6-12" of cold unconsolidated snow in below treeline terrain. Loose dry sluffs were common on steeper terrain. No obvious storm slab.
On the ridgeline found 8-12" deep, very sensitive wind slabs that we could easily trigger. They didn't extend far down the slope but could easily take out the feet of a skier with trees below.

Snowpack Details

Persistent Weak Layers:

Not observed

Avalanche Details

Avalanche Type:

Wind Slab

Failure Plane/Weak Layer:

New/old snow interface

Trigger

Trigger:

Skier

Trigger Modifier:

Intentionally Triggered

Terrain

Start Zone Slope Angle:

37degrees

Aspect:

North

Starting Elevation:

near-treeline

Size

Destructive Size:

D1 Relatively harmless to people.

Relative Size:

R1 Very Small

Crown Height:

1 ft

Avalanche Width (Average width):

15ft.

Avalanche Length (Vertical Run):

25ft.

People Involved

Number of people caught:

Weather Details

Elevation of Observation:

8000 - 9000 ft.

Blowing Snow:

Moderate

Wind Direction:

Southwest

Wind Speed:

Moderate

Sky Cover:

Broken - Mostly Cloudy - more than 4/8 and less than 8/8

Highest Precipitation Rate:

Very Light Snowfall (S-1 = up to .5cm /~.25 in per hour)

Precipitation:

Snow

Air temperature:

Below Freezing

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Sensitive wind slabs on Powderhouse

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Sensitive wind slabs on Powderhouse

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