Avalanche Forecast
Regions: Boundary, East Stikine, Howson, Kitimat, Nass, Ningunsaw, Northwest Coastal, Rupert, Seven Sisters, Shames, Stewart, West Stikine.
Heavy precipitation and warm temperatures may overload weak layers in the snowpack. Higher precipitation amounts may drive hazard to HIGH near Stewart and Ningunsaw.
Confidence
Moderate
Avalanche Summary
Friday: Several small loose wet avalanches were observed in the Shames Mountain backcountry.
Thursday: Two small natural and rider triggered wet slabs were observed.
Wednesday: Several naturally-triggered large (size 2) avalanches were observed in the Bear Pass area.
The potential for both natural and human-triggered avalanches is set to increase as the incoming storm affects the snowpack.
Snowpack Summary
The upper snowpack is moist or wet at treeline elevations and below. 10-15 cm of precipitation has fallen south of the Nass Valley and around Terrace. 30-50 cm has fallen near Stewart and Ningunsaw. There is potential for this accumulated storm snow and rain to overload buried weak layers
A layer of surface hoar and facets has been found around 30 cm deep at treeline and below in isolated areas. A 15 cm thick hard crust is 30-50 cm deep at treeline elevations. These layers have become unlikely to trigger, but there is potential for the warm temperatures and new precipitation to overload these deeper layers triggering large avalanches.
Weather Summary
Friday Night
Cloudy with 5-10 cm of new snow / moderate rain near Terrace, 10-20 cm near Stewart and Ningusaw / heavy rain, southwest alpine wind 30-40 km/h, treeline low 0 °C, freezing level 1100-1500 m
Saturday
Cloudy with 7-15 cm of snow in the alpine / moderate to heavy rain below, southwest alpine wind 55-75 km/h, treeline high of 1 °C, freezing level 1500m
Sunday
Cloudy with 15-30 cm snow / moderate to heavy rain, southerly alpine wind 75-80 km/h, treeline high of 3 °C, freezing level 1500-1800 m.
Monday
Cloudy with 5-10 cm of new snow / moderate to heavy rain, southerly alpine wind 70-80 km/h, treeline high of 3 °C, freezing level between 1500-1800 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Minimize exposure during periods of heavy loading from new snow and wind.
- Storm slabs in motion may step down to deeper layers resulting in large avalanches.
- As surface loses cohesion due to melting, loose wet avalanches become common in steeper terrain.
Avalanche Problems
Storm Slabs
These slabs will be most reactive at or near ridge crests, especially during periods when snow is being moved by wind onto lee slopes.
Aspects: All aspects.
Elevations: Alpine.
Likelihood: Likely
Expected Size: 1 - 2.5
Wet Slabs
Be especially cautious during periods of heavy rain as it may trigger underlying weak layers.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood: Likely
Expected Size: 1 - 2.5
Loose Wet
Use caution when encountering moist or wet snow in steep areas or gully features.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood: Very Likely
Expected Size: 1 - 1.5