Thick Melt Freeze crust. Strong overnight winds.

Location Name: 
Hard Slabs and Melt-Freeze Crust
Region: 
Williams Lake Area
Date and time of observation: 
Mon, 02/03/2020 - 12:00



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

Uncharacteristically warm weekend temperatures formed a significant melt-freeze crust on solar aspects at all elevations. Above treeline on Southern slopes this melt-freeze crust was supportable, knife hard, and thick. We found a poorly structured snowpack on these southern slopes, with multiple faceted crusts underlaying more cohesive slabs. In long column tests, these facet-crust layers fully propagated with small cut lengths.

Strong overnight Western winds, with gusts reaching the low 60's scoured all aspects above treeline and open terrain near treeline. While we did not observe wind slab formation, these winds laid down a hard surface slab on all slopes. The hard slab formed above near surface facets in some areas, and decomposing faceting slabs and weak layers in other terrain. We found these near surface facets failed under easy to moderate force, and fully propagated. Western slopes were stripped, with cross-loaded gullies the only terrain holding any snow.

We found a snowpack that is overall not strengthening, with combos of faceting crusts, and decomposing faceting slabs.   

The slick surfaces caused by the winds and melt-freeze crust made for difficult travel at higher elevations. Ski crampons would not have been a bad idea. Decent skiing was found in wind sheltered, shady terrain, where recycled powder formed. 

Temperatures reached the low to mid 50's below 9500 feet yesterday. Evidence of wet-loose avalanches was visible at all aspects, especially below treeline.

Photo 1: Strong winds overnight stripped Western slopes

Photo 2: Loose-wet slides at low elevations from extremely warm temperatures Sunday 

Snowpit or crown profile photo or graph: 
Snowpack photos: 
Weather Observations
Blowing Snow: 
No
Cloud Cover: 
75% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Moderate
Precipitation: 
None
Air temperature trend: 
Static
Wind Direction: 
West
Accumulation rate: 
None
More detailed information about the weather: 

A cold day in the teens with consistent moderate winds out of the West. Cloud cover most of the day. No precip observed.