Avalanche: Summit

Location: Palmer Creek

Date:
Observer:
Route & General Observations

We rode in from Hope to check out conditions in the Palmer Creek drainage. There were firm sun crusts on the south half of the compass, with dry snow under the crusts. All aspects had some kind of wind effect, with recent loading and avalanches on north, east, and west aspects. We made it up to a little higher than 4000′, stopping to dig a pit on a slope adjacent to a very recent natural avalanche on a N aspect at just over 3200′.

Avalanche Details
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Trigger NaturalAvalanche Type Hard Slab
Aspect North NortheastElevation 3800ft
Slope AngleunknownCrown Depth 18in
Width 150ftVertical Run 500ft
Avalanche Details

The avalanche looked to be less than a day old, on a wind-loaded slope. We dug a pit on a similar slope just below the avalanche and found a wind slab sitting on top of a layer of stellars. The runout was an abrupt transition to a flat slope, with debris piled up around 6' deep.
We saw a similar avalanche in an adjacent bowl on a similar terrain feature.

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

I noticed some shooting cracks when I was making a tight turn on a low-angle slope that had been recently wind-loaded.

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

Clear skies, with temperatures in the mid 20's to low 30's F on the road, and estimating they were in the upper teens to 20 F at higher elevations. Winds were light out of the north below about 3000', with strong westerly winds near ridgetops all day.

Snow surface

Anything on the south half of the compass had a sun crust, all the way up to our high point at 4000'. Northerly aspects still had dry snow, with some soft pockets out there but most of it had either been scoured or loaded by winds.

Snowpack

We saw multiple recent (past 24 hours) wind slab avalanches, as well as some wet loose activity.

Notes from our snowpit (N aspect, 3240'):
-Total snow depth 13 feet! This area has likely seen wind loading through the season.
-6" new/wind-loaded snow on the surface.
-A buried layer of stellars (6" deep) was failing, but not propagating in stability tests (ECTN12, CT12, CT13).
-A deeper layer of facets (18" deep) took more force to initiate, and was also not propagating in stability tests (ECTN24, CT24, CT24).

Recent avalanches and ongoing wind-loading through the day kept us conservative with our terrain choices today.

Photos & Video
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