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Avalanche: Cottonwood Canyon

Observer Name
Nate H-S
Observation Date
Saturday, February 1, 2014
Avalanche Date
Saturday, February 1, 2014
Region
Logan » Logan River » Cottonwood Canyon
Location Name or Route
Logan Cottonwood Canyon - Sisters Ridge
Elevation
8,800'
Aspect
North
Slope Angle
47°
Trigger
Natural
Trigger: additional info
Repeater
Avalanche Type
Hard Slab
Avalanche Problem
Persistent Weak Layer
Weak Layer
Depth Hoar
Depth
Unknown
Width
250'
Vertical
Unknown
Comments
Several slabs failed Saturday on the Sisters sub-ridges north of Mt. Elmer in Logan Cottonwood Canyon. The most subtle was a steep, north-facing rock band that released. We skinned up across the bowl and saw a small crown. The next skin up, the crown had more than tripled in size to several hundred feet in width. We postulate that it failed on a depth hoar layer that we had identified on similar slopes/aspects near rocks and logs. It failed as a large hard slab first, running a couple hundred feet, and then failing again, as the crown propagated further along the sub-ridge. Images were poor quality as it was snowing hard. We didn't approach this avalanche or any others due to unsafe conditions. Also apparent in Cottonwood Canyon were several repeater hard slabs that released on steep, east-facing slopes. These all failed in storm slabs over the early-season facets. Some of these extended across existing crowns, some were in steep micro-features below the initial crowns. Steep, north-facing and east-facing aspects with a touch of wind deposition were all suspect, all weekend. South and west aspects skied clean and fast, and had more complex melt-freeze and sun crusts bridging old layers to the well-bonded late-week (30-31 JAN) storm snow. Not enough loose storm snow to cause much commotion on these aspects. With more snow or big wind, the aspects where we observed natural slide could all load up for another natural persistent slab avalanche cycle.
Coordinates