Avalanche Forecast

Moderate - Uncertainty is due to the limited number of field observations. Uncertainty is due to the speed, direction, or duration of the wind and its effect on the snowpack.

Monday night: Clearing, flurries tapering to trace amounts.Moderate wind switching southwest to southeast. Alpine low -4 C. Freezing level around 800 m.

Tuesday: Increasing cloud with isolated flurries bringing up to 10 cm of new snow. Light wind from the south to southeast. Alpine high -3 C. Freezing level around 600 m.

Wednesday: Mostly cloudy with isolated flurries bringing 5-10 cm of snow. Strong southwest winds. Alpine high -3 C. Freezing level around 600 m.

Thursday: Mostly cloudy with heavy snowfall bringing 30-50 cm of snow, concentrated in the south of the region. Strong southwest winds, approaching extreme at ridgetop. Alpine high -3 C. Freezing level around 1000 m.

A few natural and skier triggered storm slab avalanches up to size 1.5 were reported over the weekend. Avalanche observations have likely been hindered by limited visibility through the storm, so we expect details of storm slab activity to come in after it clears up.

Reports of deep persistent slab avalanches have been trickling in throughout the month. They are associated with a November crust layer near the base of the snowpack which has produced very large avalanches (size 3+) with crown depths of around 2 m. Observations are typically in alpine terrain, on lee or cross-loaded slopes. 

Storm totals in the south of the region are in the range of 60-90 cm. Windslabs formed in the alpine may now be hidden by newly fallen snow due to strong southerly winds dying down towards the tail of the storm. 

The new snow rests on extensively wind affected surfaces at upper elevations, and a thick layer of weak facets in sheltered areas treeline and below.

A deep crust from mid November lurks at the base of the snowpack. A couple of recent large avalanches have run on this layer on lee and cross-loaded features high in the alpine. As this storm applies significant new snow loads to the snowpack, these deep layers will feel the stress and we may see some very large avalanches in high places.

• Continue to make conservative terrain choices while the storm snow settles and stabilizes.
• Don't let the desire for deep powder pull you into high consequence terrain.
• Avoid freshly wind loaded terrain features.
• Be aware of the potential for large avalanches due to the presence of a deep persistent slab.