Wind Slabs and Cracking on Hidden Peak

Location Name: Hidden Peak Region: West Shore Area Date and time of observation: Tue, 02/21/2017 - 14:00
Location Map: United States 38° 58' 31.0008" N, 120° 7' 27.3144" W See map: Google Maps US	Red Flags: 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:

Below 7000 ft, 6+ inches of new snow rested on top of a refreezing rain crust. Hand pits and probing found wet snow below the crust. Above 7000 ft, the new snow grew deeper and the rain crust became less prevalent. A quick snowpit on a sheltered NE aspect at 8200 found some density changes in the storm snow but fractures on these layers did not propagate across the column in Extended Column Tests. Storm snow depth at this elevation measured 2 to 3 ft. Near the summit of Hidden Peak in wind loaded terrain ski cuts and kicks triggered shooting cracks in wind slabs.

Photo 1: Shooting cracks on a wind-loaded test slope @ 8600 ft.

Photo 2 and 3: ECTN 15 and ECTN 21 at the upper and lower density changes in the storm snow @ 8200 ft.

Snowpack photos:

Shooting cracks on a wind-<a href="/avalanche-terms/loading" title="The addition of weight on top of a snowpack, usually from precipitation, wind drifting, or a person." class="lexicon-term">loaded</a> test slope @ 8600 ft.

Shooting cracks on a wind-loaded test slope @ 8600 ft. ECTN 15 at the upper <a href="/avalanche-terms/snow-density" title="The mass of snow per unit volume, but often expressed as a percent water content. New fallen powder has a low density (3-10%), while heavy or wet snow is more dense (10-20%)." class="lexicon-term">density</a> change in the storm snow

ECTN 15 at the upper <a href="/avalanche-terms/snow-density" title="The mass of snow per unit volume, but often expressed as a percent water content. New fallen powder has a low density (3-10%), while heavy or wet snow is more dense (10-20%)." class="lexicon-term">density</a> change in the storm snow

ECTN 15 at the upper density change in the storm snow ECTN 21 at the lower <a href="/avalanche-terms/snow-density" title="The mass of snow per unit volume, but often expressed as a percent water content. New fallen powder has a low density (3-10%), while heavy or wet snow is more dense (10-20%)." class="lexicon-term">density</a> change in the storm snow

ECTN 21 at the lower <a href="/avalanche-terms/snow-density" title="The mass of snow per unit volume, but often expressed as a percent water content. New fallen powder has a low density (3-10%), while heavy or wet snow is more dense (10-20%)." class="lexicon-term">density</a> change in the storm snow

ECTN 21 at the lower density change in the storm snow

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:

Cooling

Wind Direction:

Southwest

Accumulation rate:

Greater than 1 in. per hour

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Wind Slabs and Cracking on Hidden Peak

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Wind Slabs and Cracking on Hidden Peak

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