Accident: Twin Lakes Pass 4/27/2011

Observer Name:

Bruce Tremper

Observation Date:

04/27/2011

Occurrence Date:

04/27/2011

Occurrence Time:

Unknown

Region:

Salt Lake
Big Cottonwood Canyon
Twin Lakes Pass

Location Name:

Twin Lakes Pass - (between Alta and Brighton)

Location

40° 35' 38.0904" N, 111° 36' 28.5084" W

Avalanche Characteristics

Elevation:

10000'

Aspect:

Northeast

Slope Angle:

Trigger:

Unknown

Trigger: additional info:

Unintentionally Triggered

Avalanche Type:

Soft Slab

Weak Layer:

New Snow

Depth (avg):

18"

Width:

150'

Vertical:

200'

People Involved

Caught:

Carried:

Partly Buried:

Accident & Rescue Info

Accident & Rescue Summary:

Two skiers triggered an avalanche, were caught, carried and partly buried on the east side of Twin Lakes Pass. They were returning from Wolverine Cirque and there is one short section of steep slope you have to cross before you get to Twin Lakes Pass unless you loose 100 vertical feet to go around the steep section. This is the same slope that produced a fatality in similar circumstances several years ago.

The upper fracture of the fresh soft slab broke out about 70 feet above them and carried them about 40 feet into a dense stand of trees where they were partly buried. The looker's left hand lobe continued to travel downslope much farther, perhaps 200 vertical feet.

They were both OK but had to recover some of their equipment and they skied out on their own power.

The photo below shows where one of them appeared to be partially buried and you can see the fracture at the top of the photo. They were crossing mid slope between the burial site and the fracture.

A friend of mine saw the accident occur and reported it to Alta Central and made sure they could get all their equipment together and travel on their own.

Rescue Photos:

Terrain Summary:

The fracture was about 1.5 feet deep and was the new snow sliding on the slick crust from before the storm. I could not tell if it had a culprit weak layer or if it was just a weak interface. There was some graupel at the base of the slab and I thought I could see very small surface hoar as well.

Terrain Photos:

Weather & Avalanche History:

A view looking down the looker's left lobe that traveled farther downslope. The skiers were carried into a stand of trees to the left of this photo, which stopped them from traveling very far down the slope.

Weather Photos:

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