Hard Slabs Above Treeline

Location Name: 
Lake Fork
Region: 
Williams Lake Area
Date and time of observation: 
Wed, 11/27/2019 - 13:05
Location Map: 
United States
36° 33' 1.1808" N, 105° 26' 43.4544" W
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: 

Took advantage of the lull inbetween storms to get to the ridgetops to see what was happening above treeline.  We made it to the top of Lake Fork Peak.  We found that strong winds from 11/25 transported snow into 1 finger to pencil hard wind slabs above treeline.  Depths of snow varied greatly with leeward slopes and cross loaded gullies holding the most snow (3 to 4') and windward slopes stripped to bare ground.  We continued to get whumpfing and shooting cracks on north aspects above 10,500' where we have a poor snowpack structure with weak basal facets on the ground.  Extended Column Test did not produce any results where the basal facets did not exist.

Photo 1: Hard slabs formed 11/25 from strong winds.  We did not find weak basal facets on the ground in this snowpack.

Photo 2: Moderate SW winds during the day were transporting snow at ridgetops from the 6" low density snow that fell 11/26

Photo 3: Most windward slopes were stripped and transported to leeward aspects. 

Snowpack photos: 
Weather Observations
Blowing Snow: 
Yes
Cloud Cover: 
50% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Moderate
Precipitation: 
None
Air temperature trend: 
Warming
Wind Direction: 
Southwest
Accumulation rate: 
None
More detailed information about the weather: 

Below freezing temperatures throughout the day with SW winds in the 20 to 30 mph range at ridgetops. Clouds starting rolling in afternoon as the storm approached from the south.