Avalanche: Tab Hollow 2/15/2010

Observer Name:

Erik Syrstad

Observation Date:

02/15/2010

Occurrence Date:

02/15/2010

Occurrence Time:

Morning

Region:

Tab Hollow
Logan River
Logan

Location

41° 47' 15.7092" N, 111° 41' 16.0224" W

Avalanche Characteristics

Elevation:

8200'

Aspect:

Northeast

Slope Angle:

Trigger:

Skier

Trigger: additional info:

Unintentionally Triggered

Avalanche Type:

Soft Slab

Weak Layer:

Surface Hoar

Depth (avg):

12"

Width:

150'

Width Range:

100' to

150'

Vertical:

200'

People Involved

Caught:

Snow Profile

Snow Profile Comments:

Some medium density new snow (a couple inches) on a foot or so of denser snow from the past few days.

No cracking, no collapsing, no whoomphs. The weak layer in both cases was extremely thin, which may have prevented obvious collapses or other signs of instability.

Moderate wind on the ridge. No wind elsewhere, and wind-deposited snow didn't seem to play a role in the second slide.

General Comments

After triggering the first avalanche, we decided to ski some mellow tree shots well away from the main slide path. We descended the

General Comments 2

The pocket in image #4 pulled out around the corner and well above me, perhaps 60-80 feet, and luckily I had good purchase in the bed surface as the debris washed past.

General Comments 3

The small pocket in image #5 also pulled out. The entire slab was probably 100-150’ wide, with debris running maybe 200’ vertical through dense trees – it could have been a nasty ride. The complex crown shape basically mapped out where surface hoar had grown in the openings between trees. This slab was triggered at 8200' on a NE aspect.

General Comments 4

Surface hoar is clearly the main issue here. I've never seen such a low-angle slope slide. That type of protected slope is normally what I look for on high danger days.

Good outcome here since Erik was able to self arrest in the bed surface and did not get carried into the forest below....

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