Increasing instability and slab formation in the Blue Lakes area

Location Name: 
Peak 8520
Region: 
Carson Pass Area
Date and time of observation: 
Thu, 02/16/2012 - 13:45
Location Map: 
United States
38° 39' 31.464" N, 119° 55' 25.392" 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
Obvious avalanche path
Observation made by: Forecaster
Snowpit Observations
More detailed information about the snowpack: 

Snowpit data in this area showed that the Jan. rain crust and the facets underneath it continue to lose strength. As this weakening is continuing, the new snow has started to consolidate and has become more slab-like. By this afternoon extended column tests showed that moderate force can cause a break in the facet layer under the crust and that the resulting fracture can now travel through that layer in some areas. See snowpit and video attached to this observation. Click here for a video on how to do an extended column test. Even though the weak facets would collapse under the weight of either a skier or snowmobiler on most slopes today, ski and snowmobile cuts on steep northerly test slopes did not result in any failures other than some loose snow sluffing. By late afternoon a thin sun crust had started to refreeze on the lower elevation sun exposed southerly slopes.

 

Snowpit or crown profile photo or graph: 
Snowpit videos (tests, etc): 

Increasing instability and slab formation on some northerly slopes near Blue Lakes

Weather Observations
Blowing Snow: 
No
Cloud Cover: 
25% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Light
Precipitation: 
Air temperature trend: 
Cooling
Wind Direction: 
East
Accumulation rate: 
More detailed information about the weather: