Avalanche Forecast

Moderate - Forecast snowfall amounts are uncertain

Friday night: Cloudy with increasing flurries bringing 10-20 cm of new snow by morning. Moderate to strong southwest winds.Saturday: Cloudy with continuing snowfall bringing another 15-20 cm of new snow over the day. Strong southwest winds. Alpine high temperatures around -4 as freezing levels rise to 1500 metres.Sunday: Cloudy with lingering light flurries and a trace of new snow. Light to moderate northwest winds, easing over the day. Alpine high temperatures around -10.Monday: A mix of sun and cloud. Light southwest winds. Alpine high temperatures around -12.

No new avalanche activity in the region to report from Tuesday through Thursday. On Monday a natural size 3 glide avalanche was reported from a steep south facing aspect at 1500 m. The avalanche likely failed on the ground running on what looked to be a grass slope from far away.A few large (size 2-3) natural persistent slab avalanches were reported on Sunday. These avalanches were reported on south aspects in the alpine. Last week numerous persistent slab avalanches (up to size 3) were reported on all aspects (a few that even destroyed mature trees). The persistent slabs were 50-150 cm thick and likely failed on the early December weak layer. The same layer was responsible for several large human triggered avalanches earlier this month (see this MIN report for an example).Looking forward, increasing snowfall, wind, and freezing levels are setting up conditions ideal for the formation of storm slabs and natural avalanche activity. Although the likelihood of storm slabs 'stepping down' to deeper persistent slab problems is in question, travel plans should account for very large avalanches as the possible result.

A building storm is now depositing new snow on the surface. Below the new snow, a new layer of surface hoar was recently observed growing on the snow surface at treeline and above. This covers a few centimeters of low density snow from the past few days, which itself sits above a layer of wind affected snow in the alpine and around treeline.A weak layer that formed during the dry spell in early December is now 90-160 cm deep. The layer is composed of weak facets, surface hoar, and a sun crust on steep south-facing slopes. VARDA has posted a video that provides a great visual on our snowpack. This layer was previously responsible for large persistent slab avalanches, but activity has greatly diminished over the last week. Saturday's storm may breathe some life into it, the places of greatest concern will be north and east facing slopes between 1900-2300 m and steep south-facing slopes in the alpine.A weak layer from mid-November and a crust that formed in late October are found near the bottom of the snowpack. The probability of triggering these deeper layers is low, but the most suspect areas would be shallow spots in steep rocky terrain.