Avalanche danger will be highest late in the day as new snow accumulates.
A surface hoar/crust layer, down 40-80 cm has become reactive with the loading of new storm snow. This layer is most likely found in sheltered openings around treeline and below.
Storm slabs will develop through Friday as snowfall accumulates around the region, adding to snow from early this week. Expect new storm slabs to develop, and be wary of recently developed slabs hiding under fresh snow.
Thursday night: Scattered flurries, 5-10 cm. Alpine temperature -5 C, southwest wind 25-40 km/hr.
Friday: Snow, 10-20 cm. Alpine temperature -3 C, southwest wind 25-35 km/hr.
Saturday: More snow, 10-20 cm. Alpine temperature -4, southwest wind 20-30, gusting to 45 km/hr.
Sunday: Sunny with cloudy periods. Alpine temperature -10 C, north wind 10-20 km/h.
On Wednesday, storm snow continued to be reactive to skier traffic, including triggering slab avalanches to size 2 and cracking on small, supported slopes. A couple of field observations reported slab avalanches failing on a layer of surface hoar (down 60-80 cm) at treeline elevations.
On Tuesday, a natural avalanche cycle was observed in Glacier National Park. Numerous size 2 storm slab avalanches were observed on all aspects at 2200 m and above. Additionally, 2 size 3 storm slab avalanches were observed on a north aspect at 2165 m and a northwest aspect at 2400 m. Near Revelstoke, storm slab avalanches to size 2 were reacting easily to explosives, many occurring on north and northeast aspects from 1800-2300 m.
Storm snow totals reached 30-50 cm early this week along with moderate westerly winds. Slabs have formed in areas exposed to wind.
The storm snow covered a faceted upper snowpack and previously wind-affected surfaces, and surface hoar in sheltered areas around treeline and below.
Down 40-80 cm, a layer of surface hoar (feathery crystals) may be found in sheltered areas around treeline. In these areas old, stubborn wind slabs may still be reactive where they overly the weak surface hoar on a crust.
A variety of crusts from late October are buried deeper in the snowpack. Total snow depths range from 100-170 cm around tree line.
