Wind Slabs and Shooting Cracks on Tamarack Peak

Location Name: 
Tamarack Peak
Region: 
Mount Rose Area
Date and time of observation: 
Fri, 12/23/2016 - 13:30
Location Map: 
United States
39° 18' 47.7936" N, 119° 54' 46.1952" 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: 

4 to 6 inches of new snow had fallen by early afternoon in the Tamarack Peak area today. In sheltered areas, cracking around our skis while skinning, hand pits, and formal snowpit work indicated that the new snow was not bonding well to the old snow surfaces. In sheltered areas, new snow accumulation had not yet reached a point where storm slabs had become widespread, but observations did indicate that if enough new snow accumulates storm slabs could pose a problem today. In these areas, soft new snow rested on a more dense layer of new snow that all rested on top of the old loose weak snow (near surface facets).

In more exposed areas continuous and significant wind loading was occurring all day.  By 1 pm wind slabs up to 16 inches deep had formed in wind loaded areas. Ski cuts on wind loaded test slopes triggered small wind slab avalanches and shooting cracks up to 20 ft. in length. These wind slabs also failed on the old snow surface. 

Photo 1: Wind slab failure triggered by a skiers weight on a NE facing test slope at 9360 ft. 

Photo 2: Cracking on a wind loaded test slope.

Video: Wind slab failure on the same test slope as shown in photo 1.

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

Wind Slab Failure on a Wind Loaded Test Slope

MVI 3331

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: 
Cooling
Wind Direction: 
Southwest
Accumulation rate: 
Less than 1 in. per hour