Avalanche Forecast

Tuesday night: Cloudy with continuing snowfall bringing 25-40 cm of new snow. Moderate southwest winds becoming strong at ridgetop.

Wednesday: Cloudy with continuing snowfall bringing 15-25 cm of new snow and 2-day snow totals to 50-90 cm, continuing overnight. Light to moderate southwest winds. Alpine high temperatures around -5.

Thursday: Mainly cloudy. 3-day snow totals of 60-100 cm and flurries beginning overnight. Light west winds. Alpine high temperatures around -10.

Friday: Cloudy with flurries bringing 5-10 cm of new snow, totaling 15-20 cm with overnight accumulations. Flurries continuing overnight. Moderate south winds, becoming strong at ridgetop. Alpine high temperatures around -4.

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 in the neighbouring 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. 

Looking forward, continuing snowfall is expected to maintain dangerous avalanche conditions, with storm slabs and persistent slabs becoming increasingly likely to trigger.

A variable 10-30 cm of new snow has buried 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. Snowfall is forecast to continue through Wednesday night.

The new snow adds to 10-30 cm of low density snow we received late last week. This older storm snow has been blown into wind slabs in some exposed areas, but in most places it 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. In some places it may begin to behave as a primary storm slab interface below our new snow accumulations.

110 to 180 cm of snow is now resting on a widespread layer of large, feathery, surface hoar from mid-December. 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. 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.

• Be aware of the potential for large avalanches due to the presence of buried persistent weak layers.
• Storm slab size and sensitivity to triggering will likely increase through the day.