Variable Snowpack Depths

Location Name: 
Lake Fork
Region: 
Williams Lake Area
Date and time of observation: 
Thu, 01/23/2020 - 12:00


Red Flags: 
Whumphing noises, shooting cracks, or collapsing

Observation made by: Professional Observer
Snowpit Observations
More detailed information about the snowpack: 

Went for a tour in the Williams Lake drainage. Moderate winds out of the northwest with gusts in the low 40s were transporting snow from ridgelines to leeward slopes. We did not observe wind slabs forming. While traveling, the snow surface varied between Tuesdays new snow to the hard slab which formed on 1/17. In open wind effected terrain, this hard slab made for difficult skinning at times. The hard slab was present on all aspects near and above treeline. Primarily underlying the new snow from Tuesday it sits atop various persistent weak layers, from small grained facets, faceted crusts and depth hoar. 

We have highly variable snowpack depths. On southern aspects we have deceivingly shallow slopes, with a poor overall snowpack structure. See Video The hard slab sits atop various faceted crusts, with large 5-6mm depth hoar at the base. We got these persistent weak layers to fail under light force. We got loud audible whumfs and shooting cracks on these slopes.  

Our Northern and Eastern slopes also have differing snow depths. Its hard to tell what slopes avalanched during our 1/17 avalanche cycle. In some spots that didn't slide, we found the snowpack to be over 3 meters deep. A much shallow snowpack was found near rock bands. Tuesdays 4-6" sit on top of a hard slab. This hard slab overlies small grained facets, which failed under moderate to hard force with full propagation.    

West aspects remain stripped, except for cross loaded gullies. Inverted tracks were noticeable.  

Photo 1: Winds scoured Western slopes, with only cross loaded gullies holding snow.

Photo 2: 5-6mm depth hoar, which underlies faceted crusts and a hard slab.

Snowpit or crown profile photo or graph: 
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: 
Static
Wind Direction: 
Northwest
Accumulation rate: 
None
More detailed information about the weather: 

Cold day with temps in the mid teens to low 20s. Consistent moderate winds out of the North Northwest, with gusts into the low 40's. Clouds covered around half of the sky. No precip.