Avalanche Forecast

 

THURSDAY NIGHT: Lingering flurries overnight with 5-10 cm of snow, strong wind from the south, freezing level rapidly dropping, alpine temperatures drop to -15°c. FRIDAY: Isolated flurries in the morning then clearing in the afternoon, moderate wind from the west, alpine temperatures around -12°c. SATURDAY: Increasing cloud, light wind from the south, alpine high temperatures around -10°c. SUNDAY: Mostly cloudy with isolated flurries, moderate wind from the south, alpine high temperatures around -7°c.

Large natural and human triggered avalanches (size 2-3) have been reported regularly over the past week. Many avalanches reported were triggered remotely (from a distance). A notable human triggered size 2.5 avalanche occurred in Allan Creek on Saturday. The avalanche was triggered on a northeast facing alpine slope. A report of this avalanche can be found on the Mountain Information Network here. A size 4 natural avalanche was reported to have run full path, burying a road on the west side of Kinbasket Lake. This avalanche occurred in the North Columbia region, but it is a significant event and is very close to the boundary between the North Columbia and Cariboo regions. These full path avalanches can catch people by surprise, especially when there is little to no snow in the valley bottoms. A report of this avalanche can be found on the MIN here.

Recent storms have deposited 80-120 cm of new snow. This new 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. A weak layer from mid-November is now buried up to 150 cm and consists of surface hoar in shady locations, and a sun crust on steep south facing slopes. The potential may exist for smaller avalanches to step down and trigger this deeper layer, resulting in very large avalanches. The most likely place for this layer to be a problem is on steep, south facing slopes at treeline where the surface hoar sits on the sun crust. At the base of the snowpack is a crust that formed in late October. The probability of triggering this layer is low, but the most suspect areas would be large, steep, rocky alpine features with a shallow snowpack.