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Observation: Turnagain

Location: Twin Peaks

Date:
Observer:
Route & General Observations

Skinned up the Eastern face of Twin Peaks to treeline ~2800′.

Red Flags
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Observer Comments

No obvious signs observed

Weather & Snow Characteristics
Please provide details to help us determine the weather and snowpack during the time this observation took place.
Weather

Broken to overcast skies
-7F at the car at 10am and 12F when we returned at 3pm
Calm winds
Light precip, no noticeable accumulation

Snow surface

*Near surface facets and surface hoar of varying sizes the entire route

700' - 1000' - 1cm of NSF and SH were on a supportable Melt-Freeze crust
1000' - 1300' - two breakable MF crusts could be felt in the top 20cm of the snowpack and disappear around 1300'.
Above 1300' - 6-10" of settled powder on firmer snow below

Found a thin (3mm) rime crust capping 3mm surface hoar. This was 5cm below the surface sandwiched between wind hardened snow at 2800'. See last photo.

Old avalanche debris was seen in the prominent gully between the two twin peaks on East aspect. It was covered with new snow likely from New Years and ran to around 2000'.

Snowpack

The height of snow at 2000' on ENE aspect varied from 90cm to 120cm. We dug two pits side by side and found similar structure. The weak layer was ~40cm below the surface, on decomposing fragments on a 1/2 step density change. One small 2mm piece of buried surface hoar was found on this layer, but couldn't find anymore. Compression tests failed with Moderate force with a clean sheer Q1. Extended Column tests did not propagate. There was a crust near the ground with moist rounding facets in one pit and moist crust in the other. No test results on basal layers.

The height of snow at 2800' NE aspect varied from 100cm to 170cm. We dug two pits near each other. One pit in a deep area (160cm) and the other in a shallow area (100cm.) Several weak layers were found in the top 45cm of the snowpack, on density changes between 1F and Pencil hard decomposing fragments. Compression tests failed with moderate to strong force on several of these density changes and Extended Column tests did not propagate, but failed under the blade similar to CT's.

*We did notice that the decomposing fragments in both locations were starting to form edges (slight faceting), and were .25-.5mm in size.

Photos & Video
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