Avalanche on I-80

Location Name: 
Cisco Grove
Region: 
Donner Summit Area
Date and time of avalanche (best estimate if unknown): 
Fri, 02/25/2011 - 09:15
Location Map: 
United States
39° 18' 55.2276" N, 120° 33' 30.9168" W
See map: Google Maps
US


Red Flags: 
Obvious avalanche path
Observation made by: Public
Avalanche Observations
Avalanche Type: 
dry,slab,
Slope: 
35degrees
Trigger type: 
Natural
Aspect: 
Northeast
Avalanche Width: 
300ft.
Terrain: 
Near Treeline
Avalanche Length: 
100ft.
Number of similar avalanches: 
1
More detailed information about the avalanche: 

Avalanche over I-80 stopped eastbound traffic for approximately one hour on Friday morning. The snow underneath a cornice on a NE aspect (unknown slope angle) failed, with a 12" crown propogating nearly the entire length of the slope. Snow covered the interstate, traffic was stopped until caltrans removed all the debris. No people or cars were caught in the slide. While waiting for the plow truck to do his duty, I jumped up on the slope and dug a quick test pit, noticing approximately 2 feet of new, unconsolidated snow on an ice crust. A quick compression test revealed CTE 1 Q1.

 

 

 

Weather Observations
Blowing Snow: 
Yes
Cloud Cover: 
100% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Strong
Precipitation: 
Snow
Air temperature trend: 
Warming
Wind Direction: 
West
Accumulation rate: 
Greater than 1 in. per hour
More detailed information about the weather: