Avalanche Forecast

The intense winter storm will ease off Friday night. A weak ridge of high pressure will strengthen over the Interior and generate strong outflow winds along with residual flurries for the weekend. A warm front is expected to invade the region Monday night, with widespread snow and significantly warmer temperatures. 

FRIDAY NIGHT: Flurries / Freezing level at valley bottom / Moderate west wind / Low of -18

SATURDAY: Flurries / 10-15 cm overnight / Freezing level at valley bottom / Moderate southwest wind peaking to 60 km/h at night / High of -12

SUNDAY: Cloudy / Freezing level at valley bottom / Moderate south wind / High of -8

MONDAY: Snow / Freezing level rising to 500 m / Moderate south wind / High of -5

A very large storm slab avalanche (size 3) ran naturally in Mount Revelstoke National Park on Friday afternoon. This avalanche path rarely affects the road, but debris piled up to 3 m on the highway just outside Revelstoke. 

Thursday, riders released multiple small storm slab avalanches on small terrain features as the storm snow accumulated. Few natural loose dry avalanches were also observed on steep terrain features at treeline and below treeline. 

The limited visibility in the alpine restricted observations on Thursday and Friday, but we suspect that a natural avalanche cycle occurred at night Thursday or early morning Friday. 

Although the persistent Dec crust/facets layer has seen more activity in the south and east region corner of BC (details and photos here) it remains a serious concern for the North Columbias region, particularly as the current storm is bringing more snow.

The region received 40 to 50 cm low-density snow and constant 50 km/h southerly wind since the start of the storm Thursday. This new snow is falling on a variety of surfaces, thin sun crust on solar aspects, isolated surface hoar at treeline on sheltered slopes, fresh wind slabs in lee alpine features at treeline and above or even previous storm snow (20-60 cm) from the last weekend's storm.

We're actively monitoring the early December crust. In some places, it's scoured and on the surface, while in wind-loaded terrain features it can be found as deep as 150 cm below the surface. It consists of faceted grains above a bulletproof crust formed by the Atmospheric Rivers of early December. There has been isolated avalanche activity on this crust in the last week that seems to be confined to complex alpine terrain. 

• Don't be too cavalier with decision making, storm slabs may remain sensitive to human triggering.
• Be aware of the potential for human triggerable storm slabs at lower elevations, even on small features.
• Storm slabs in motion may step down to deeper layers resulting in large avalanches.