Avalanche: Summit

Location: Colorado

Date:
Observer:
Route & General Observations

We skinned up to 2900′ and dug on NE and SE aspects. We found reactive wind slabs 3-10″ deep as we got above treeline. We got shooting cracks, poor stability test results, and were able to get an old wind slab to release with a ski cut on a steep, wind-loaded rollover.

Avalanche Details
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Trigger SkierAvalanche Type Hard Slab
Aspect East SoutheastElevation 2800ft
Slope Angle 38degCrown Depth 8in
Width 20ftVertical Run 100ft
Avalanche Details

I ski cut a wind slab on a small but steep convexity. The wind slab failed on top of a layer of near-surface facets, which was about 6-10" deep.

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

There was an inversion all day, with temperatures near 0 F at the parking lot at 10:00, and around 15 F at 2900' at noon. Valley fog stuck around until around 2:00, and skies were clear above about 1800' all day. Winds were calm, with an occasional light southeasterly breeze.

Snow surface

There was 4-6" soft snow at the surface up to about 2700', where there was an abrupt transition to various wind textures and lots of very stiff slabs.

Snowpack

The snowpack is quite variable above treeline at Colorado. Here's what we found in our pits:

NE aspect, 2900' (total depth 3-4')
-6-10" thick, stiff wind slab on top of a thin layer of faceted snow. The bottom 2-3' of the snowpack was apparently all wind-packed, with 1-finger to pencil hard snow all the way down to the ground.
-ECTP18 failed on the near-surface facets, about 10" deep.

SE aspect, 2890' (total depth 8-9')
-A skiff of soft snow sitting on a thin, knife-hard wind slab. The wind slab was sitting on a layer of faceted snow.
-There was a layer of decomposing precip particles, with some facets, buried 1.5-2' deep. We got CT23 and CT19 on this layer, both tests were Q2 and PC.

Photos & Video
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