Wind Slab Instability On Castle Peak

Location Name: Castle Peak/Andesite Peak Region: Donner Summit Area Observation Date & Time: Wednesday, March 14, 2018 - 12:00
Location: 39.364620, -120.361083 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 Obvious Slide Path Trigger Points Terrain Traps Terrain Matches the Advisory

Location Name:

Castle Peak/Andesite Peak

Region:

Donner Summit Area

Observation Date & Time:

Wednesday, March 14, 2018 - 12:00

Location:

39.364620, -120.361083

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

Obvious Slide Path

Trigger Points

Terrain Traps

Terrain Matches the Advisory

Observation made by: Forecaster

Tabs

Observation

Description of Snow, Weather, and Avalanche Conditions:

12 to 15'' of new snow in Castle Valley with an additional 4'' accumulating during our ski tour. Snowing up to 1'' per hour at times with consistent snowfall throughout the day. Moderate SW winds were blowing snow above 8200' in wind exposed terrain. Shooting cracks were occurring in wind loaded terrain with reactive wind slabs up to 2' deep that would fail with a ski kick above slope. Rain soaked snow layer 4-6'' thick was found below the new storm snow. Minimal storm slab cracking observed in below treeline terrain.

Shooting cracks with wind slab release on E aspect, 8000', on Castle Ridge.

1.5 to 2' deep wind slab on NW aspect, 8250', 35 degree slope.

Natural wind slab/cornice release partially covered by additional snow.

Weather Details

Elevation of Observation:

7000 - 8000 ft.

8000 - 9000 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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Wind Slab Instability On Castle Peak

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Wind Slab Instability On Castle Peak

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