Avalanche Forecast

Tuesday night: Cloudy with continuing flurries bringing 5-10 cm of new snow. Light to moderate south winds shifting southwest. 

Wednesday: Cloudy with continuing flurries bringing 5-15 cm of new snow and 2-day snow totals to 20-40 cm, continuing overnight. Moderate to strong west winds. Alpine high temperatures around -5.

Thursday: A mix of sun and cloud with 3-day snow totals of 25-45 cm. Light to moderate west winds easing over the day. Alpine high temperatures around -14.

Friday: Cloudy with snowfall bringing 15-25 cm of new snow, continuing overnight. Moderate to strong southeast or south winds. Alpine high temperatures around -9.

Reports from the weekend included several notable MIN reports from the Barkerville area, where shooting cracks, whumphing, and both natural and machine triggered storm slabs were observed failing on a 20 cm-deep surface hoar layer. (This layer is being buried increasingly deeply by ongoing snowfall.) 

One of these reports included a large (apparently older) persistent slab release near a large glide crack. 

Reports from the interior of the region on Saturday included other observations of several recent small (size 1.5) natural wind slab releases. These occurred between 1800-2300 metres on steeper northeast aspects and featured crown depths of up to 40 cm.

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

A variable 10-30 cm of new snow has buried a new layer of large surface hoar that was observed on the surface in sheltered areas of the region in advance of the storm. This interface may instead present as a thin sun crust on steep, sun exposed aspects.

The new snow adds to 15-30 cm of recent storm snow which was either blown into soft wind slabs in alpine lees or remains low density. The interface below this snow may present as surface hoar on sheltered, shaded aspects, as a sun crust on steep sun-exposed aspects or as a more widespread melt-freeze crust below about 1700 metres. Reactivity at this layer has been noted in recent MIN reports and in some places it may continue to behave as a primary storm slab interface.

A widespread layer of large, feathery, surface hoar from mid-December can likely now be found 80-150 cm deep. Activity on this interface has tapered off, but there is concern for loading from forecast snowfall to reinvigorate avalanche activity at this depth.

A weak layer formed in late November is now buried around 1 m or more below the surface. Concern for this layer is limited to variable snowpack depth areas in the high alpine where it most likely exists as a combination of facets and crust.

• Use conservative route selection. Choose simple, low-angle, well-supported terrain with no overhead hazard.
• Storm slab size and sensitivity to triggering will likely increase through the day.
• Be aware of the potential for large, destructive avalanches due to the presence of deeply buried weak layers.