Avalanche on Sisters Near Round Top

Location Name: 
Sister's
Region: 
Carson Pass Area
Date and time of avalanche (best estimate if unknown): 
Sat, 11/21/2009 - 11:55
Location Map: 
United States
38° 39' 51.0048" N, 120° 0' 41.7204" W
See map: Google Maps
US


Red Flags: 
Whumphing noises, shooting cracks, or collapsing
Recent loading by new snow, wind, or rain
Obvious avalanche path
Observation made by: Public
Avalanche Observations
Avalanche Type: 
dry,slab,
Trigger type: 
Skier
Crown Height: 
2 ft
Aspect: 
North
Avalanche Width: 
200ft.
Terrain: 
Above Treeline
Elevation: 
9 800ft.
Bed Surface: 
Old Snow
Avalanche Length: 
1 000ft.
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."

Avalanche Photos: 
Weather Observations
Blowing Snow: 
No
Cloud Cover: 
Clear
Air temperature: 
Below Freezing
Wind Speed: 
Calm
Precipitation: 
None
Air temperature trend: 
Static
Wind Direction: 
Accumulation rate: 
None
More detailed information about the weather: