Purcells

Fresh wind slabs will form at higher elevations on Thursday. Watch for conditions changing over the day.

Moderate - Intensity of incoming weather systems is uncertain

Thursday: An incoming storm wave will deliver 10-20cm of new snow. Winds moderate gusting to strong from the southwest. Freezing level rising to 1000 metres with alpine temperatures to -8.Friday: Mostly cloudy with isolated flurries and a trace of new snow. Winds light gusting to moderate from the west. Freezing level to 800 metres with alpine temperatures around -10.Saturday: A mix of sun and cloud with isolated flurries and a trace of new snow. Winds light from the west. Freezing level dropping to valley bottom with alpine temperatures to -12.

Several natural size 1.5 avalanches were observed in the region on Tuesday, with crown depths of up to 40cm. These occurred at high elevations and are attributed to wind slabs that have grown with recent wind and snow loading. An ACMG Mountain Conditions Report from Christmas day describes a slab avalanche failing on a steep, north facing slope at 2100m. This avalanche remains relevant for having stepped down 110cm to the November crust. The size of the avalanche is unknown, but this speaks to the touchy nature of persistent slabs in the area. On Christmas eve, a skier was partially buried in a size 2 slab avalanche while skinning up a northeast facing slope at about 2000m. The failure plane of this avalanche is unknown although the depth (40cm) suggests the mid-December weak layer may have been the culprit. Check out the Mountain Information Network post for more details.

Between 15-20cm of new snow has fallen in the past few days. Moderate southwest winds have been redistribute the loose surface snow into new wind slabs in exposed higher elevation terrain. A highly variable 20-80 cm of snow typically overlies the mid-December interface which consists of stiff wind affected snow, faceted (sugary) crystals, and surface hoar that formed in sheltered areas. The overlying slab appears to have a poor bond to these surfaces in some areas, especially in wind-affected terrain in the Dogtooth range and possibly Quartz Creek. In sheltered terrain, the overlying slab has remained soft. As it continues to settle and gain cohesion, we may start to see a more widespread persistent slab problem develop. The thick mid-November crust/ facet layer typically sits 70-140 cm down in the snowpack. Recent avalanche activity in the Dogtooth Range suggests this layer has woken up and has the potential for large avalanches. Check out this ACMG Mountain Conditions Report for more info: https://mountainconditions.com/reports/december-25th-dogtooth-range-november-crust-awakening