Avalanche: Portage / Placer

Location: Placer Valley - above Spencer Glacier

Date:
Observer:
Route & General Observations

Rode into and above the Placer Valley, Spencer Glacier and Skookum Glacier to see the extent of the northwest wind event.

Avalanche Details
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Trigger SnowmachinerAvalanche Type Soft Slab
Aspect SouthwestElevation 1000ft
Slope Angle 40degCrown Depth 8in
Width 50ftVertical Run 80ft
Avalanche Details

Small snowmachine triggered wind slab avalanche.

*Additionally - we had a report of a skier triggered persistent slab avalanche nearby in more treed terrain at 800' in elevation, W aspect. That photo is below and from another party, no one caught. This avalanche was 12-16" deep at the maximum and failed on buried surface hoar. It was small terrain so not a big avalanche.

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)?Yes
Observer Comments

Strong northwest wind transporting snow off the high terrain all day.
One small wind slab triggered, mentioned earlier.
Some cracking in new wind blown snow, but we did not venture into steep suspect terrain.

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

Clear skies and cold, single digits.
Strong NW winds.

Snow surface

Variable. Wind scoured, anti-tracks to soft settled powder in sheltered areas. In general however, most places are wind damaged.
It appeared that 6-8" of new snow fell last Tues/Wed (Feb 16-17). This was not enough to cover old tracks.

Snowpack

We dug one pit at 3,400' on a sheltered West aspect. Snow depth deeper than probe.
ECTN down 10" on a layer of decomposing particles and old graupel of all things.
Surface was 4 finger hardness becoming pencil hard 16" down. Right side up in top 2.5 feet that we tested.
*We were looking for weak layers of buried surface hoar and facets, but found none - likely do to the area seeing too much wind over the past month.

Photos & Video
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