Avalanche Forecast
Regions: Boundary, East Stikine, Howson, Kitimat, Nass, Ningunsaw, Northwest Coastal, Rupert, Seven Sisters, Shames, Stewart, West Stikine.
Avoid all avalanche terrain.
Unseasonable warm weather will likely result in a widespread natural avalanche cycle.
Confidence
High
Avalanche Summary
Widespread natural avalanche activity occurred across the region on Thursday. Several very large persistent slabs and wet avalanches (loose and slabs) were reported at all elevations. With this forecasted warming, we expect a widespread avalanche cycle on slopes that did not avalanche yet.
Snowpack Summary
Thursday, the region received 15 to 20 cm of wet snow (or rain at lower elevations). This warm snow was redistributed by southerly winds at upper elevations. This overlies the settled 40 to 80 cm of storm snow. Several persistent weak layers are now buried between 90 and 180 cm deep, including hard crusts with overlying weak facets and surface hoar. These weak layers have been responsible for continued avalanche activities over the last week. At lower elevations, the upper snowpack is wet.
Weather Summary
Thursday Night
Cloudy with 5 mm of rain expected or wet snow in alpine. 50 to 70 km/h southwest ridgetop wind. Treeline temperatures around +3 °C. Freezing level rising to 2500 m.
Friday
Cloudy with no precipitation. 30 to 50 km/h southwest ridgetop wind. Treeline temperatures around +6 °C. Freezing level rising to 3000 m.
Saturday
Mainly cloudy and sunny periods with no precipitation. 30 to 40 km/h southwest ridgetop wind. Treeline temperatures around +8 °C. Freezing level around 3500 m.
Sunday
Mix of sun and clouds with no precipitation. 50 to 60 km/h southwest ridgetop wind. Treeline temperatures around +5 °C. Freezing level rising to 2500 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Avoid exposure to overhead avalanche terrain as temperatures increase.
- Persistent slabs have potential to pull back to lower angle terrain.
- Cornice failure may trigger large avalanches.
- Very large and destructive avalanches could reach valley bottom.
Avalanche Problems
Persistent Slabs
The likelihood of persistent slab avalanches will increase with each day of warm weather. A widespread avalanche cycle is expected on slopes that did not avalanche yet.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Very Likely
Expected Size: 2 - 3.5
Loose Wet
Intense warming will likely trigger numerous wet loose and wet slab avalanches. These may step down to deeper weak layers resulting in larger-than-expected avalanches.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Very Likely
Expected Size: 1 - 2