Negro Canyon

Location Name: 
East Fork Negro Canyon
Region: 
Donner Summit Area
Date and time of avalanche (best estimate if unknown): 
Fri, 02/05/2010 - 11:00
Location Map: 
United States
39° 20' 44.4552" N, 120° 17' 39.426" W
See map: Google Maps
US


Red Flags: 
Recent avalanche activity
Whumphing noises, shooting cracks, or collapsing
Recent loading by new snow, wind, or rain
Observation made by: Professional Observer
Avalanche Observations
Avalanche Type: 
dry,slab,
Slope: 
36degrees
Trigger type: 
Natural
Crown Height: 
1 ft
Aspect: 
Northeast
Weak Layer: 
Other
Avalanche Width: 
100ft.
Terrain: 
Below Treeline
Elevation: 
7 300ft.
Bed Surface: 
Old Snow
Avalanche Length: 
200ft.
Number of similar avalanches: 
3
More detailed information about the avalanche: 
Observations were made in Negro Canyon on an exposed ridge that had lots of wind loading overnight.  45-55cm of new snow at this location.  All failures were at a density change just above the old snow/new snow interface.  Cornices are very tender and built out being the trigger of most of the slide activity I saw today.    Photo#1: Natural avalanche partially covered up by new snow.  3 similiar slides occuring on E-NE aspects 7200-7500', all seemed to occur with a cornice failure as the trigger.  Photo#2: From a small sub ridge, a small ski kick released the cornice which fractured around this small bowl about 150' wide and ran downhill about 150' where the slope angle decreased.
Snowpit or crown profile photo or graph: 
Avalanche Photos: 
Avalanche observation video: 

ECTP-12

Weather Observations
Blowing Snow: 
Yes
Cloud Cover: 
75% of the sky covered by clouds
Air temperature: 
Above Freezing
Wind Speed: 
Moderate
Precipitation: 
Snow
Air temperature trend: 
Static
Wind Direction: 
Southwest
Accumulation rate: 
Less than 1 in. per hour
More detailed information about the weather: