Purcells

Conditions are changing. Avalanches will become more likely and more dangerous as forecast new snow amounts gradually accumulate.

Poor - Intensity of incoming weather is uncertain

Tuesday: A Pacific frontal system arrives bringing around 5 cm new snow and strong westerly winds, which at ridge top could reach 100 km/h. Freezing levels will rise to around 1500 m in the afternoon. Wednesday: the cold front associated with the system moves through, bringing around 10 cm additional snow and bringing freezing levels down later in the day to around 1000 m. Winds should become moderate northwesterly. Thursday: Dry, with light northwesterly winds and freezing levels around 800 m.

On Sunday, a size 2.5 avalanche was triggered remotely from 20m away. It ran on surface hoar buried 45cm below the surface on an east aspect at 2500 m. Elsewhere (and more typically), small avalanches could be triggered in the top 20 cm of snow by ski cutting. As we get incremental amounts of new snow above this interface, we inch closer to the tipping point, when more widespread and dangerous avalanches start to occur. This concept is discussed in more detail in the latest Forecaster Blog post.

Widespread surface hoar has been buried by around 15-20cm of new snow in most of the region. The exception is terrain closer to the Bugaboos, where the interface is down 30-40cm. A melt-freeze is also associated with this weak interface on southerly aspects at all elevations. North and east aspects continue to have dry snow and some surface sloughing in steep terrain. Basal facets have not been reactive, but operators continue to monitor this layer in tests. Triggering this deep persistent weak layer is unlikely, but shallow snowpack areas or shallow weak areas adjacent to deeper wind loaded slopes are suspect locations.