Avalanche Forecast

Poor - Intensity of incoming weather is uncertain

Overnight Tuesday: 5-15cm new snow expected with freezing levels around 1500 m and strong to extreme westerly ridge top winds. Wednesday: a cold front moving through will bring only light snowfall, say 2-4 cm. Temperatures will drop in the afternoon, with freezing levels lowering to around 800 m. Windy--expect ridge top winds up to 70 km/h. Thursday: lingering flurries, winds diminishing to moderate northwesterly, and freezing level lowering to around 500 m. Friday: Cloudy with a chance of flurries.

On Tuesday, a size 1.5 skier-triggered avalanche was reported on a north aspect at 2400 m with a fracure depth of 45 cm. This avalanche, along with a number of similar naturally-triggered avalanches that also occurred, was triggered on a layer of surface hoar buried 45 cm deep. On Monday, natural and human triggered avalanches up to size 2 were reported from the Bugaboos, also running on a layer of surface hoar buried 20-60 cm deep. On Sunday, a size 2.5 avalanche was triggered remotely from 20m away. It too ran on surface hoar buried 45cm below the surface on an east aspect at 2500 m.

Widespread surface hoar has been buried anywhere between 20 and 60cm of new snow. The places where this layer is buried by the most snow are those close to the Bugaboos and also areas where extensive wind transport has taken place. A melt-freeze is also associated with this weak interface on southerly aspects at all elevations. North and east aspects continue to have relatively low density snow near the surface and some surface sloughing in steep terrain--this may change with anticipated warm temperatures and high winds. 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 the most suspect locations.