Avalanche Forecast
Regions: Boundary, East Stikine, Kispiox, Ningunsaw, Northwest Coastal, Northwest Inland, Stewart, West Stikine.
Continued reports of human-triggered persistent slab avalanches show buried weak layers remain sensitive
Careful snowpack evaluation and conservative decision-making are essential
Confidence
Moderate
Avalanche Summary
On Friday, a size 1.5 and a size 2 human-triggered persistent slab avalanches were reported in open alpine features at 2000 m.
Reports from earlier this week observed both natural and human-triggered wind slab and persistent slab avalanche activity to size 3 in the alpine. These avalanches were 20 to 40 cm deep and were all suspected of running on a weak layer of surface hoar buried in early March.
Snowpack Summary
Southerly winds have redistributed 20 to 40 cm of recent snow into deep pockets on lee slopes. This snow buried a widespread layer of large surface hoar crystals, which sits on a crust on solar aspects and at low elevations. This layer has been reactive in recent days where a slab has consolidated above.
A layer of facets, surface hoar and/or a crust from mid-February is buried 50 to 100 cm deep. This layer produced large natural and human-triggered avalanches last week.
The remainder of the snowpack is well consolidated with no concerns at this time.
Weather Summary
Saturday Night
Cloudy with light flurries, 1 to 5 cm of snow. 20 to 30 km/h south ridgetop wind. Treeline temperature -10 °C.
Sunday
Cloudy with light flurries, 2 to 3 cm of snow. 15 to 25 km/h southwest ridgetop wind. Treeline temperature -8 °C.
Monday
A mix of sun and clouds. 15 to 30 km/h west ridgetop wind. Treeline temperature -11 °C.
Tuesday
Cloudy with light flurries, 1 to 5 cm of snow. 20 to 30 km/h southwest ridgetop wind. Treeline temperature -6 °C.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Be careful with wind-loaded pockets, especially near ridge crests and rollovers.
- Be aware of the potential for large avalanches due to buried weak layers.
- Keep in mind that human triggering may persist as natural avalanches taper off.
- In times of uncertainty, conservative terrain choices are our best defense.
Avalanche Problems
Wind Slabs
South winds have redistributed recent snow into alpine and treeline lee terrain features. Wind slabs may be more reactive where they overlie a buried weak layer of surface hoar.
Aspects: North, North East, East, West, North West.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1 - 1.5
Persistent Slabs
Two weak layers of facets and/or surface hoar that were buried mid-February and early March continue to be reactive to human triggering. Make conservative terrain choices and avoid exposure to overhead hazards.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1.5 - 3