Avalanche Forecast

Heavy snowfall and strong winds are expected to impact the north of the region

Thursday night: 

North: Overcast, 5-10 cm of snow, moderate to strong south winds, freezing level dropping to 1400 m. 

South: Mostly cloudy, a trace of snow, moderate south winds, freezing level dropping to 1700 m.

Friday: 

North: Overcast, 10-15 cm of snow, moderate to strong south winds, freezing level rising to 1500 m then falling to 500 m. 

South: Mostly cloudy, a trace of snow, moderate south winds, freezing level rising to 2000 m then falling to 500 m. 

Saturday: Mostly cloudy, isolated flurries with trace accumulations, light southwest winds, freezing level near 1300 m.

Sunday: Mostly cloudy, isolated flurries with trace accumulations, light southwest winds, freezing level near 1200 m.

In the north of the region, natural and human-triggered avalanches from new snow and wind are likely on Friday. 

There are still concerns about the reactivity of persistent weak layers in these areas. Over the past week, observers near Duffey Lake reported a large (size 2.5) avalanche on a north aspect at 1750 m that was thought to have released 1 m deep on a persistent weak layer. On Sunday, a size 1.5 skier accidental was reported on a northwest aspect in the alpine, also near Duffey Lake. The slab is thought to have failed on a thin layer of facets, sandwiched between two wind-stiffened layers. 

In the south of the region, an observer submitted this MIN report of large wet avalanche activity near Manning Park on Tuesday. In the Coquihalla area, several natural glide slab avalanches size 2-2.5 have been observed. Glide slabs are notoriously difficult to forecast but with the sustained warming, we may see continued activity. Glide slabs are most likely in areas of smooth ground cover such as rock slabs at lower elevations experiencing prolonged warm temperatures with limited overnight refreeze. These avalanches will be large, involving the full depth of the snowpack. Carefully consider your access/egress routes where they cross under large paths. 

The focus for avalanche hazard in the region shifts to the north with an incoming storm. Above freezing temperatures remain a concern in the south of the region on Friday, but danger ratings are a full step lower (Considerable, Considerable, Moderate). 

In the north of the region, an incoming storm is forecast to bring 15-25 cm of snow by midday on Friday. Strong south winds will contribute to rapid slab formation, making natural avalanches likely. The combination of wind and snow has the potential to weaken cornices, which can act as triggers on slopes below. 

The rapid load from new snow and wind has the potential to wake up buried weak layers. A layer of facets from mid-February has shown reactivity on north aspects near treeline and is primarily a concern where it separates wind-stiffened snow above and below. A deeper persistent weak layer buried in late January composed of a crust, facets or surface hoar also has the potential to re-awaken with large triggers, such as an avalanche in motion, cornice fall, or intense loading from snow/ wind. The lower snowpack is well settled and strong in most areas.

In the south of the region, the snowpack is generally well consolidated with no concerns of buried weak layers.

• Watch for fresh storm slabs building throughout the day.
• Dial back your terrain choices if you are seeing more than 20 cm of new snow.
• Use conservative route selection. Choose simple, low-angle, well-supported terrain with no overhead hazard.
• Storm slabs in motion may step down to deeper layers resulting in large avalanches.
• Avoid steep slopes when air temperatures are warm, or solar radiation is strong.