Avalanche on Sisters Near Round Top

Location Name:

Sister's

Region:

Carson Pass Area

Location

United States

38° 39' 51.0048" N, 120° 0' 41.7204" W

See map: Google Maps

Position:

Public

Date and time of avalanche (best estimate if unknown):

Sat, 11/21/2009 - 11:55am

Red Flags:

Whumphing noises, shooting cracks, or collapsing

Recent loading by new snow, wind, or rain

Obvious avalanche path

Avalanche Observations

Avalanche Type:

Dry

Avalanche Type:

Slab

Trigger type:

Skier

Aspect:

North

Elevation:

9800ft.

Bed Surface:

Old Snow

Crown Height:

2 ft

Avalanche Width:

200ft.

Avalanche Length:

1000ft.

Terrain:

Above Treeline

Avalanche Photos:

More detailed information about the avalanche:

This slide was reported by three different observers. The avalanche seems to have been remotely triggered by a party on a nearby skin track.

Observer 1's comments: "It happened thirty seconds before we hit the small saddle. Propagated all the way across the slope...The facets failed and the slide slid on the ice layer below. [We did two test pits.] Test pit 1 failed before first strike dug on a North-northwest aspect. Test pit 2 west-north-west, failed on 3rd tap."

Observer 2's comments: "Avalanche ran full path from just under the peak to round top lake. It appeared to be skier triggered by a group of four, but could have already been there (doubt it because you can see it from the trail up and I doubt they would have skied there if they saw the slide first)... We also experienced significant whumpfing in our area which was 2 bowls toward round top."

Weather Observations

Blowing Snow:

Wind Speed:

Calm

Air temperature:

Below Freezing

Air temperature trend:

Static

Cloud Cover:

Clear

Precipitation:

None