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Newly Forming Wind Slabs on Castle Peak

Location Name: Castle Peak Region: Donner Summit Area Date and time of observation: Wed, 01/18/2017 - 11:00
Location Map: United States 39° 21' 52.4556" N, 120° 21' 37.116" 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

Snowpit Observations

More detailed information about the snowpack:

Snowfall and wind intensity was increasing throughout the morning. By 12pm , 2-4'' of new snow had fallen and strong SW winds were forming sensitive and reactive wind slabs with 6-8'' crowns along exposed ridgelines. New storm snow was high density and was bonding well to old snow surfaces we encountered.

Snowpack photos:

$Skier <a href="/avalanche-terms/trigger" title="A disturbance that initiates fracture within the weak layer causing an avalanche. In 90 percent of avalanche accidents, the victim or someone in the victims party triggers the avalanche." class="lexicon-term">triggered</a> <a href="/avalanche-terms/wind-slab" title="A cohesive layer of snow formed when wind deposits snow onto leeward terrain. Wind slabs are often smooth and rounded and sometimes sound hollow." class="lexicon-term">wind slab</a> @ 11am. 8300', N/NW <a href="/avalanche-terms/aspect" title="The compass direction a slope faces (i.e. North, South, East, or West.)" class="lexicon-term">aspect</a>, 6-8'' <a href="/avalanche-terms/crown-face" title="The top fracture surface of a slab avalanche. Usually smooth, clean cut, and angled 90 degrees to the bed surface." class="lexicon-term">crown</a> line.$
Skier triggered wind slab @ 11am. 8300', N/NW aspect, 6-8'' crown line. <a href="/avalanche-terms/cornice" title="A mass of snow deposited by the wind, often overhanging, and usually near a sharp terrain break such as a ridge. Cornices can break off unexpectedly and should be approached with caution." class="lexicon-term">Cornice</a> formation along ridge at 10:30am.

<a href="/avalanche-terms/cornice" title="A mass of snow deposited by the wind, often overhanging, and usually near a sharp terrain break such as a ridge. Cornices can break off unexpectedly and should be approached with caution." class="lexicon-term">Cornice</a> formation along ridge at 10:30am.

Cornice formation along ridge at 10:30am. Debris from small <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> failure.

Debris from small <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> failure.

Debris from small wind slab failure.

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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Newly Forming Wind Slabs on Castle Peak

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Newly Forming Wind Slabs on Castle Peak

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