South Columbia

Avalanche hazard will rise with incoming snow and increased winds. In areas that accumulate more than 30cm snow, bump the avalanche danger to HIGH.

Moderate - Intensity of incoming weather systems is uncertain.

WEDNESDAY NIGHT: Flurries, accumulating 5-10cm. Moderate south wind. Freezing level 1000m. THURSDAY: Snow, accumulating 10-30cm, increasing through the day. Moderate southwest wind with strong gusts. Freezing level rising to 1500m. FRIDAY: Cloudy with isolated flurries, up to 5 cm snow. Light to moderate west-northwest wind. Freezing level valley bottom. SATURDAY: Cloudy with isolated flurries, up to 5cm snow. Light south wind. Freezing level valley bottom.

The storm snow is still reactive, especially in wind-loaded areas. Explosives and skier activity have triggered avalanches to size 2, and natural avalanches failing within the storm snow continue to be reported. Numerous natural and explosives triggered avalanches to size 3.5 and human triggered avalanches to size 2 have been reported in the region daily since Wednesday, December 12. Many of these avalanches were triggered from a distance (remote triggered) and two remote triggered avalanches (size 1.5-2) were reported on Monday. A skier was caught in an avalanche on Sunday on a west aspect at around 2000 m on a small slope, which released at a depth of 50 cm on buried surface hoar.

Approximately 70-120cm of recent storm snow sits on a weak layer of facets (sugary snow), surface hoar (feathery crystals) and a sun crust (on south aspects). Strong winds have promoted widespread slab formation, particularly with the most recent new snow available for transport. Another weak layer of surface hoar and sun crust that formed in mid November is up to 120cm below the surface. This layer is most likely to be a problem in areas where the surface hoar sits on the sun crust. This combination is most likely found on steep, south facing slopes at treeline. The potential may exist for smaller avalanches to step down and trigger this deeper layer, resulting in large avalanches. At the base of the snowpack is a crust that formed near the end of October. Concern for this layer is dwindling but it may still be worth considering in places such as steep, rocky, alpine terrain, especially where the snowpack is shallow. It would likely take a large trigger such as a cornice fall to produce an avalanche on this layer.