Wind slabs and shooting cracks on Tamarack Peak

Location Name: 
Tamarack Peak
Region: 
Mount Rose Area
Date and time of observation: 
Thu, 04/12/2012 - 12:00
Location Map: 
United States
39° 18' 47.1024" N, 119° 54' 18.6156" 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: Forecaster
Snowpit Observations
More detailed information about the snowpack: 

An average of 4-8 inches of new snow existed on top of frozen supportable crusts in the Tamarack Peak area today. In more sheltered areas and in more wind scoured areas less than 3 inches of new snow existed on the snow surface. In wind loaded areas more new snow had piled up. Wind slabs up to 2 ft deep had formed on leeward slopes near ridgelines in above treeline terrain. Ski cuts on wind loaded test slopes produced shooting cracks up to 15 ft long. Slab failures up to 18 inches deep did occur on the most heavily wind loaded test slopes with either no support at the bottom of the slope or on slopes that had been previously undercut. The failure layer for the cracks and wind slabs was a density change near the base of the new snow.

Photo 1: Shooting crack on a NE facing wind loaded slope.

Photo 2: Wind slab failure on a small wind loaded test slope that ended in a creek.

 

Snowpack photos: 
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: 
Static
Wind Direction: 
Southwest
Accumulation rate: 
Less than 1 in. per hour
More detailed information about the weather: 

Several squaws blew through the area bringing heavy graupel and strong southwest winds at regular intervals. One of these convective storms even produced some thunder around 12:30 pm. In between the squaws the clouds thinned and patches of sunshine appeared.