Avalanche: Summit

Location: Colorado

Route & General Observations

Went on a short bushwhack to conduct a detailed analysis of a shallow snowpack. We only made it halfway up the ridge before the we began to run out of sunlight and snacks and decided to return to the truck. We had some great breaks in the alders that made for awesome skiing on the way down.

Avalanche Details
If this is an avalanche observation, click yes below and fill in the form as best as you can. If people were involved, please provide details.
Trigger NaturalRemote Trigger No
Avalanche Type Hard SlabAspect Southwest
Elevation 3000ftSlope Angleunknown
Crown DepthunknownWidthunknown
Vertical Rununknown  
Avalanche Details

We did not get close enough to analyze so these observations are approximate.

We saw two avalanches from the NE ridge of Colorado. The first occurred in the Gulley between Colorado and Fresno. This avalanche was the product of wind effect and cross loading of snow into the Gully on Monday. We are not sure what the slope angle was but we can estimate it was about 35˚. The debris at the bottom of the slide was still in big chunks, the product of a hard slab avalanche.

The second slide occurred across the valley from where we were skiing on Colorado in big terrain features on Butch. This slide also was initiated by wind loading, it ran to the bottom of the couloir below it and fanned out. This slide could be considered a D2, large enough to bury a person.

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
Observer Comments

Cracking under our skis but nothing that was shooting.

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

Despite the forecast for incoming clouds we had sunny skies throughout the day and into the evening. There was a slight breeze but nothing noteworthy. We noticed an inversion from the car up and out of the valley where temps at the car were around 5˚ and higher elevation temps seemed to settle around 20˚.

Snow surface

Surface condition 1: Wind buffed. 1-4" wind crust on isolated micro-terrain features (convexities and gullies).

Surface condition 2: Consolidated/settled surface snow about 1-2" deep on top of a faceting crust layer.


A generally thin and weak snowpack structure exits in Summit Lake.

At lower elevations (1000'-2000') below the tree/alder line the snow depth was about 1 meter deep consistently. There was a stiff wind/facet layer that did not bond well to the new snow /wind loaded snow above it. About 20 cm deep we were able to identify a dual melt freeze crust layer with 2 cm of soft facets between them.

We dug a pit at a higher elevation site ( 2749') on a NE aspect. The snow above the alders was about 25 cm less than the snow at lower elevations. This was mainly due to increased wind effects and snow transport. At the wind slab and older snow interface we found large decomposing stellars and some small buried surface hoar that made the layer reactive when tested (CT1, ECTPV). Below that a facet interface saw no propagation on a small/fragile melt freeze crust about 1' deep (ECTN 17). At the ground we found well developed depth hoar that was forming cups and chains.

Photos & Video
Please upload photos below. Maximum of 5 megabytes per image. Click here for help on resizing images. If you are having trouble uploading please email images separately to staff.