Avalanche Forecast

Moderate - Forecast snowfall amounts are uncertain.

Monday night: Cloudy with flurries bringing 5-10 cm of new snow. Light to moderate southwest winds.

Tuesday: Cloudy with continuing flurries bringing 15-25 cm of new snow and new snow totals to 20-35 cm, continuing overnight. Moderate southwest winds. Alpine high temperatures around -5.

Wednesday: Cloudy with easing flurries bringing about 5 cm of new snow and 2-day snow totals to 40-60 cm, continuing overnight. Light to moderate southwest winds. Alpine high temperatures around -5.

Thursday: A mix of sun and cloud. 3-day snow totals of 45-70 cm. Light northwest winds. Alpine high temperatures around -11.

A large (size 2-2.5) persistent slab was triggered by a skier in the Selkirks near Revelstoke on Sunday. The avalanche occurred just below a convex roll situated above a rocky cliff band at 2300 metres and is suspected to have failed on one of our mid-December surface hoar layers. Its crown fracture was up to 60 cm deep.

Reports from Saturday were mainly limited to small (size 1-1.5) natural and skier triggered dry loose sluffs in steep terrain. One size 1 skier triggered wind slab was observed in the alpine in the Revelstoke area.

Observations from the North Columbias included some larger wind slab releases, including one which triggered a very large, 3 metre-deep persistent slab on a high alpine face. 

The spectacularly large and destructive natural avalanche cycle observed during last week's big storm has for the most part ended, however, persistent slabs have continued to react to explosives and other large triggers and have been reported up to size 3.

Previous snow surfaces that are now being buried across the region are a mix of large surface hoar from below treeline into the alpine, in places either combined with rime crust or replaced by sun crust on steep sun-exposed aspects.

In exposed areas at higher elevations, recent moderate southwest winds have formed some isolated wind slabs with the 10-30 cm of low density snow we received late last week. Elsewhere this recent snow remains unconsolidated. The interface below it may present as a sun crust on steep sun-exposed aspects, as surface hoar in more sheltered lower elevations, or as a more widespread melt-freeze crust below about 1700 metres.

100 to 160 cm of snow is now resting on a widespread layer of large, feathery, surface hoar from mid-December. This layer was the primary failure plane in a large natural avalanche cycle last week. Activity on this interface has tapered off, but there is some concern for loading from forecast snowfall to reinvigorate avalanche activity at this depth

Another weak layer formed in late November is now over 170 cm deep and is has become inactive. Concern for this layer is limited to rocky or variable snowpack depth areas in the alpine where it most likely exists as a combination of facets and crust.

• Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
• Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
• Carefully evaluate steep lines for wind slabs.