Avalanche: Turnagain

Location: Seattle Ridge

Route & General Observations

Quick trip up Seattle Ridge this afternoon to take a look at some recent avalanches and search for buried surface hoar/ near-surface facets. We found large surface hoar on the bed surface of the avalanche that failed at the top of Main Bowl, as well as in multiple pits in Warmup Bowl and Triangle Bowl. The only place we couldn’t find it was in a pit down by Seattle Creek near the headwall.

We also saw debris from a very large recent avalanche on the southwest end of Warmup Bowl that ran to the bottom of the bowl. All of the signs we saw from the snowpack were concerning, especially with another round of snow on the horizon.



Avalanche Details
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Trigger NaturalRemote Trigger No
Avalanche Type Hard SlabAspect Northwest
Elevation 2800ftSlope Angleunknown
Crown DepthunknownWidth 3000ft
Vertical Run 1500ft  
Avalanche Details

The avalanche on the southwest end of Warmup Bowl was big. It left a big debris pile that ran all the way to the bottom of the bowl and a little ways down a gulley heading towards Seattle Creek. We couldn't get a look at the crown, but based on what we saw in pits and at the crown of another avalanche in Main Bowl, it is most likely this avalanche was a thick wind slab on top of surface hoar.

We also saw multiple smaller wind slabs just below the cornices in Warmup Bowl and Triangle Bowl.

Red Flags
Red flags are simple visual clues that are a sign of potential avalanche danger. Please record any sign of red flags below.
Obvious signs of instability
Recent Avalanches?Yes
Collapsing (Whumphing)?No
Cracking (Shooting cracks)?No
Weather & Snow Characteristics
Please provide details to help us determine the weather and snowpack during the time this observation took place.

Partly cloudy skies with light easterly winds along the ridge. It was 38F in the parking lot at 2:00 p.m., but it was cold enough on the ridge to keep the snow dry.

Snow surface

Some of the terrain near the ridgeline had gotten hit by the winds, but there was still around 6" soft snow on the surface up high, with 8-12" at lower elevations on the back side.


There is a widespread layer of buried surface hoar about 8-10" deep on average, especially at the mid and upper elevations. In most places this layer is sitting on a firm surface and capped by a stiff (4F+ hardness) slab. This was the setup for the avalanche at the top of Main Bowl reported yesterday, and was giving us propagating test results in snowpits. We dug in 5 different places and found this layer in 4 of the pits.

It was a little surprising to not see more activity given all of the tracks up there. This is going to be a concerning layer as we are looking at getting more snow in the middle of the week.

Photos & Video
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