Observation: Turnagain

Location: Seattle Ridge (south side)

Date:
Observer:
Route & General Observations

Rode back along the Seattle Ridge (to the south from the uptrack), to checkout the snowpack and reassess all the avalanche activity from a week prior. Kept slope angles low and traveled cautiously.

Red Flags
Red flags are simple visual clues that are a sign of potential avalanche danger. Please record any sign of red flags below.
Observer Comments

We did not see any obvious signs of instability. However, this is normal for a deep persistent slab avalanche problem.

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

Overcast to obscure skies.
Temps in the 20'sF.
Winds light from the east.

Snow surface

4" of light snow on a crust at the parking lot.
Around 1,500' soft settled powder with around 4-5" of new snow from the day before.

Snowpack

Deep snowpack issues: We dug in one spot, SE face at 2,800'. This was just off Seattle Ridge and between a series of 5 slab avalanches that were triggered a week prior on the SE face (road side). Of note, 5 more were triggered on the same day on the westerly side. We wanted to take a better look at the snowpack structure at this site (along the ridge) as we know there were up to 10 large avalanches triggered from this ridge by 2 riders on 1/5.

We found the Thanksgiving crust anywhere from a couple inches to 18" above the ground. It was a melt-freeze complex around 3" thick. Weak facets were below. A lot of wind blows in this area but the crust seemed to be fairly uniform across the ridge. The snow (slab) above the crust was anywhere from non-existant to many (10+) feet deep. We dug in an area where the slab was around 3' deep. Results were a deep tap test in the 20's and ECTX, meaning we could not get a failure from a regular ECT test but isolating the deep layer we could get it to pop. Again, this is typical for deep slab issues - stability tests do not work in these cases. Our main goal was simply to confirm the structure of the snowpack and existence of the Thanksgiving crust with facets around it.

Surface snow issues: The new snow from 1/11 (4-5") fell on buried surface hoar and near surface facets. Despite this, the new snow seemed to be wanting to bond to the underlying snow in areas we traveled. This was not the case the day prior according to reports.

Photos & Video
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