Cornice collapse over Railway tunnels at Donner Summit

Location Name: Sugar Bowl Drive and Railway Tunnel Region: Donner Summit Area Observation Date & Time: Sunday, April 16, 2023 - 12:45
Location: 39.316675, -120.329761 See map: CalTopo	Is this an Avalanche Observation?: Yes Conditions Alerts: Other Signs of Instability (cracking, whumpfing, collapsing) Terrain Alerts: Terrain Traps

Observation made by: Public

Tabs

Observation

Description of Snow, Weather, and Avalanche Conditions:

Sunny day at the summit. Driving to Sugarbowl was east going up 40. I noticed while driving that the tunnel had been blocked by a cornice collapse.

Snowpack Details

Persistent Weak Layers:

Not observed

Terrain Details

Terrain: elevations:

Below Treeline

Avalanche Details

Avalanche Type:

Cornice

Failure Plane/Weak Layer:

Old Snow

Trigger

Trigger:

Unknown

Size

Destructive Size:

D2 Could bury, injure, or kill a person.

Relative Size:

R3 Medium

Crown Height:

More than 10 ft

Avalanche Width (Average width):

30ft.

Avalanche Length (Vertical Run):

20ft.

People Involved

Number of people caught:

0

Number of partial burials:

0

Number of full burials:

0

Weather Details

Elevation of Observation:

6000-7000 ft.

Blowing Snow:

None

Wind Direction:

Northwest

Wind Speed:

Moderate

Sky Cover:

Clear

Precipitation:

None

Air temperature:

Above Freezing

Sponsors:

CA OHMVR

Heavenly Mountain Resort

Mammut

Mt. Rose Ski Tahoe

Kirkwood Mountain Resort

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