The recent snow has helped the ski quality, but strong alpine winds have created new wind slabs in lee alpine areas. While the wind slabs may seem manageable, the primary concern is the threat of superficial slabs stepping down to the deep persistent weakness resulting in full-depth avalanches.
Moderate to strong south through west winds continue to build slabs in lee features in the alpine and down into treeline. The new snow with continued winds on Monday will promote further slab development. This is a particular concern where wind slab failures could step down to deeper facet layers.
Weak facets and depth hoar associated with crusts near the base of the snowpack continue to produce slab avalanches 60-100 cm deep. Any area with a stiffer slab over the mid-pack and deep facets has the potential to generate an avalanche that steps down to the deep layers and end up being quite large.
Becoming cloudy overnight on Sunday with moderate to strong SW winds at ridgetops that continue into Monday. A mix of sun and cloud on Monday with more cloud to the west, and treeline temperatures steady around -6°C.
The ski hills continued to trigger deep persistent slabs with explosives on Saturday and Sunday, up to size 2.5, failing on the basal facets/crust.
On flights and field trips we have observed failures at both the new wind slab interface and the deep persistent problem since the latest storm on Dec 18, but natural avalanche activity has slowed down in the past couple days.
4-8 cm of snow on Sunday over ~20 cm of storm snow from last week. This snow, combined with strong W/SW winds, created wind slabs in alpine lee areas and down into treeline.
The mid and lower snowpack is faceted and weak, with facet/crust interfaces near the ground. This is more pronounced east of the divide, while western regions display a deeper snowpack with fewer facets.
Snowpack depths at tree-line are about 60 cm in eastern areas and closer to 100 cm west of the divide.
