Avalanche: Turnagain

Location: Seattle Ridge

Route & General Observations

We rode up Seattle Ridge to check out the avalanche that was remotely triggered by a snowmachiner yesterday. We wanted to see if it failed within the storm snow or if there is a weak layer it failed on, and we found that it had failed on a layer of surface hoar that was buried last week. We also saw multiple avalanches that had failed during and right after last weekends storm, with big avalanches in Zero bowl as well as the front side of Seattle Ridge. The snow was soft and deep in the flats as well as up high where it was not wind affected.

After we got a look at the crown, we moved on down the ridge to do some repairs to the weather station. Wind speeds should be more reliable now after we replaced some parts on the anemometer.

Avalanche Details
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Trigger SnowmachinerRemote Trigger Yes
Avalanche Type Soft SlabAspect Northwest
Elevation 2300ftSlope Angle 32deg
Crown Depth3ftWidth 300ft
Vertical Run 500ft  
Avalanche Details

We got up to the crown of an avalanche that was triggered remotely yesterday. The avalanche had failed on a layer of buried surface hoar, and parts of the start zone were as low as 31 degrees.

Weather & Snow Characteristics
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Mostly sunny skies and mild winds down low with stronger winds from the west on Seattle Ridge.

Snow surface

Soft fresh snow from the parking lot to the just below the ridge. Surface hoar was found in the flats and higher up sporadically in isolated areas. On the ridge the snow was wind affected.


We took a look at the crown face on the backside of Seattle Ridge. We found a weak layer of buried surface hoar on the bed surface. These are concerning findings because it means this weak layer was preserved well enough to become a persistent problem.

The soft slab avalanche was at 2300' on a 31-degree northwest slope. The crown averaged 2-4' deep and 300' wide.

See attached photos for detailed snowpack information from the crown profile.

Photos & Video
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