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Observations

Region: Turnagain
Location: Tincan to 3200'
Observer:
Date:

Route & General Observations

Standard route along SW ridge of Tincan to 3200′ on ridge above Common Bowl. We toured along South facing slopes the entire way monitoring surface conditions with afternoon warming. The snow was wettest and weakest below 2500′ on steep South aspects. In shady areas on North and West aspects the crust remained firm and supportable. In the upper elevations South aspects had 3-5″ of wet pushable surface snow, but it wasn’t breaking down like the lower elevation areas.

Red Flags

Observer Comments

Wet punchy snow on South aspects below 2500' in the afternoons with warming.

Weather

Weather

Sunny and clear
Temps mid 40F's
Winds were light from the West
No new precip

Snow Characteristics

Snow surface

Below 2000' South aspects were wet and punchy. Ski pen was 6-10" in some places and boot pen was up to mid thigh at 2:30pm. A stout supportable crust was found on shaded aspects. Surface crust were softening on lower angle oblique SW aspects. As we ascended to 2500' South aspects started becoming less punchy and more supportable with boot pen only 8-10" on steep South aspects. On shaded aspects above 2500' 1cm of loose snow was found on a firm surface crust. This crust was becoming breakable by 2800' and disappeared by 3000'. South aspects between 2500' to the ridge above Common bowl (3200') there was about 2-3" of loose wet surface snow that was easy to start pushing, but did not entrain deeper into the snowpack.

Sun cups were present below 1800' and old rain runnels were seen between 1800' to 2500'.

Firnspiegal was found on SE aspects in the alpine. The avalanche glossary definition: "An ice crust formed on the snow surface on sunny, cold days. The sun's heat penetrates the surface snow layers and causes melt around the grains beneath the surface but meltwater at the surface is refrozen forming a thin layer of ice. This requires just the right heat balance."

Snowpack

Dug two pits at 3200' on Tincan. One on Southeast aspect and the other on North aspect.

Pit 1 - SE aspect, 3200', 22*slope, HS=305cm, Pit HS=100cm, Boot pen=15cm of wet surface snow. See photo diagram. Several melt/free crusts (old sun crusts) were found within the top 18" of the snowpack. Compression Test failed with moderate force just below these crusts, but ECT's had no failure. In both places the weak layer was a density change, no persistent grain types were found.

Pit 2 - North aspect, 3200', 31* slope, HS=275cm, Pit HS=120cm. See pit diagram. Stability tests failed inconsistently between three weak layers in this pit. 2 compression tests failed on a layer of rime particles 30cm below the surface with moderate force. One compression test failed with moderate force on a density change from Pencil to 1 Finger 40cm below the surface on intact stellar. An Extended Column Test also propagated on this layer, but was resistant planar. One compression test failed with moderate force 105cm below the surface on the Jan.21 buried surface hoar and facet layer. This layer was not visible in the pit wall and the hardness difference was 1F- to P above and below.

Photos & Video

Photos



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