Avalanche Forecast

Moderate - Timing, track, or intensity of incoming weather system is uncertain

The ridge of high pressure that has been producing cold, dry conditions is breaking down and allowing active weather systems into the region starting Saturday. Around 5 cm of snowfall is expected on Saturday with strong northwest winds and treeline temperatures around -10C. Heavy snowfall is forecast to start Saturday night and up to 40 cm is possible by Sunday afternoon. Alpine winds should remain strong on Sunday but are forecast to shift to the southwest. Freezing levels are forecast to rise to around 800 m on Sunday. Another period of heavy snowfall with strong winds is currently forecast for Sunday overnight and into Monday.

No recent avalanches have been reported in this region. Ongoing strong winds have formed hard wind slabs in exposed terrain which may still be reactive to human triggering in isolated areas. Touchy new winds slabs are expected to form on Saturday with the forecast for light snowfall and strong alpine winds. As the storm ramps up Saturday night and Sunday, a widespread storm slab problem is expected to develop. The surface hoar layer from mid-November may still be reactive in isolated areas and is creating a low probability, high consequence problem. As new load accumulates over the weekend, this layer is expected to increase in reactivity where is still exists.

Clear skies and strong outflow winds have created a variety of snow surfaces including scouring and hard wind slabs in exposed areas. Faceting of the upper snowpack and surface hoar up to 12 mm has in reported in sheltered areas. The new snow is expected to bond poorly to this interface. A layer of surface hoar which was buried mid-November is down 60-120 cm in many parts of the region. This layer has been dormant recently but may increase in reactivity as the storm adds new load to the snowpack. Treeline snow depths are around 140-200 cm in the Terrace and Stewart areas, but substantially less further north. Concerns in the north are basal weaknesses that may exist in the shallower snowpack areas especially on smooth alpine features like glaciers.