Winds slabs remain a concern in the alpine and exposed areas at treeline. Persistent slab avalanches may still be possible in some areas with a heavy trigger or thin-spot triggering.
Summary
Confidence
Fair - Due to the number of field observations
Weather Forecast
A mix of sun and cloud is expected for Thursday and Friday with freezing levels around 1500m and moderate-to-strong alpine winds from the SW. Unsettled conditions are forecast for Saturday with a mix of sun and cloud, light flurries, strong SW winds in the alpine, and freezing levels climbing to over 2000m.
Avalanche Summary
On Tuesday, explosives triggered 3 persistent slabs up to size 2. These released on the mid-Dec layer down 40-60cm. They were all on east aspects around 2000m elevation. On Monday, explosives triggered a size 2.5 deep persistent slab on the early-Nov layer near the ground. This was on an east aspect at 1700m in the Harvey Pass area. Natural avalanche activity is generally not expected on Thursday. Human-triggering remains a concern, especially in wind loaded areas and steep unsupported terrain features.
Snowpack Summary
10-20cm of snow fell last weekend. Moderate-to-strong SW wind has and will continue to redistribute snow in the alpine and will continue to load leeward features. The storm snow buried a layer of surface hoar and/or a crust that exists in many places up to 1900m. At higher elevations the new slow fell on widely wind affected surfaces. The mid-December crust layer is down 40-80cm. In many places this crust is overlaid by facets and/or surface hoar. In areas where the overlying slab is thick and cohesive, large avalanches remain possible on this interface. Closer to the ground a crust/facet interface that formed in November is generally dormant.
rbuhler,
Avalanche Canada
