Avalanche on Tallac

Location Name: Tallac east Ridge Region: Desolation Wilderness Area (including Emerald Bay) Observation Date & Time: Wednesday, March 25, 2020 - 15:30
Location: 38.919829, -120.101095 See map: CalTopo	Is this an Avalanche Observation?: Yes Conditions Alerts: Avalanche Activity Other Signs of Instability (cracking, whumpfing, collapsing) Rapid or Prolonged Warming Rapid or Prolonged Warming›Warm Temperatures Recent Loading Recent Loading›Blowing Snow Recent Loading›More Than a Foot of New Snow Terrain Alerts: Terrain Matches the Advisory

Observation made by: Guide at Alpine Skills International (ASI)

Tabs

Observation

Description of Snow, Weather, and Avalanche Conditions:

Wind slabs, storm slabs forming with daytime highs and breaks of sun, ski triggered loose drys wide spread. We did not observe naturals but new snow very sensitve to skier trigger. I did not take the time to do a crown profile to check for surface hoar.

Update: Forecasters visited this site on 3/26 and found that this avalanche failed on a buried layer of surface hoar. Click here for more details.

Snowpack, Avalanche, Weather Videos:

avalanche on tallac north ridge, wind slab rider triggered

Terrain Details

Terrain: elevations:

Above Treeline

Near Treeline

Below Treeline

Terrain: aspects:

Avalanche Details

Avalanche Type:

Wind Slab

Failure Plane/Weak Layer:

New/old snow interface

Trigger

Trigger:

Snowboarder

Trigger Modifier:

Accidentally Triggered

Terrain

Start Zone Slope Angle:

34degrees

Aspect:

East

Starting Elevation:

above-treeline

Size

Destructive Size:

D2 Could bury, injure, or kill a person.

Relative Size:

R2 Small

Avalanche Width (Average width):

70ft.

Avalanche Length (Vertical Run):

100ft.

People Involved

Number of people caught:

Number of partial burials:

Number of full burials:

Weather Details

Elevation of Observation:

6000-7000 ft.

7000 - 8000 ft.

8000 - 9000 ft.

Blowing Snow:

Moderate

Wind Direction:

West

Wind Speed:

Moderate

Sky Cover:

Overcast - Cloudy - 8/8 covered

Highest Precipitation Rate:

Light Snowfall (S1 (S-1 = 1 cm /~.5 in per hour)

Precipitation:

Snow

Air temperature:

Below Freezing

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Avalanche on Tallac

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avalanche on tallac north ridge, wind slab rider triggered

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Avalanche on Tallac

Conditions Alerts:

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avalanche on tallac north ridge, wind slab rider triggered

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