The last avalanche forecast for the 2023-2024 season will post on April 21st. Thank you to all who contributed to the avalanche center this season through observations, volunteer time, and/or financial contributions.

Avalanches in Negro Canyon

Location Name: Negro Canyon Region: Donner Summit Area Date and time of avalanche (best estimate if unknown): Tue, 01/10/2017 - 11:30
Location Map: United States 39° 20' 40.578" N, 120° 17' 38.886" W See map: Google Maps US	Red Flags: Recent avalanche activity Whumphing noises, shooting cracks, or collapsing Recent loading by new snow, wind, or rain

Observation made by: Forecaster

Avalanche Observations

Avalanche Type:

Dry

Slab

Slope:

40degrees

Trigger type:

Natural

Aspect:

East

Elevation:

7 200ft.

More detailed information about the avalanche:

Evidence of natural avalanche activity covered up by recent storm snow on steep wind loaded east aspects. Visibility was very poor with strong to gale force SW winds along ridgeline. On small test slopes below 7000', wind slabs were tender and failing easily up to 2' deep. These wind slabs were failing about 4-6'' above the old snow rain crust within the recent storm snow. Cornices were very large and built out along ridgelines.

Avalanche Photos:

$Intentially skier <a href="/avalanche-terms/trigger" title="A disturbance that initiates fracture within the weak layer causing an avalanche. In 90 percent of avalanche accidents, the victim or someone in the victims party triggers the avalanche." class="lexicon-term">trigger</a> <a href="/avalanche-terms/wind-slab" title="A cohesive layer of snow formed when wind deposits snow onto leeward terrain. Wind slabs are often smooth and rounded and sometimes sound hollow." class="lexicon-term">wind slab</a> on small test slope$
Intentially skier trigger wind slab on small test slope

<a href="/avalanche-terms/wind-slab" title="A cohesive layer of snow formed when wind deposits snow onto leeward terrain. Wind slabs are often smooth and rounded and sometimes sound hollow." class="lexicon-term">Wind slab</a> failing within storm snow about 4-6'' above the old snow <a href="/avalanche-terms/rain-crust" title="A clear layer of ice formed when rain falls on the snow surface then freezes." class="lexicon-term">rain crust</a> interface.

Wind slab failing within storm snow about 4-6'' above the old snow rain crust interface.

Weather Observations

Blowing Snow:

Yes

Cloud Cover:

100% of the sky covered by clouds

Air temperature:

Below Freezing

Wind Speed:

Strong

Precipitation:

Snow

Air temperature trend:

Static

Wind Direction:

Southwest

Accumulation rate:

Greater than 1 in. per hour

More detailed information about the weather:

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Avalanches in Negro Canyon

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Avalanches in Negro Canyon

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