Avalanche Forecast
Issued: Dec 29th, 2024 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs and Wind Slabs.
Avalanche Canada,
Avalanche Canada
A problematic weak layer has been producing large, hair-triggered avalanches north of Terrace. Careful snowpack evaluation and conservative decision-making are critical.
Summary
Confidence
Moderate
Avalanche Summary
Avalanche activity near Shames was limited to small (size 1-1.5) rider-triggered wind slabs on Saturday.
Between Terrace and Ningunsaw, large (size 2-3) natural and remotely-triggered persistent slab avalanches have been reported in recent days. These avalanches have been triggered from hundreds of meters away, failing on the early December weak layers and running on the early December crust. Check out these sobering MIN reports (1, 2) near Rosswood on Saturday.
Snowpack Summary
Extensively wind-affected surfaces exist in the alpine. Soft snow can be found in sheltered and lower elevation terrain. Below 1000 m, surface snow is moist and/or crusty.
50 to 100 cm of snow settles over a significant weak layer. The layer involves weak grains of surface hoar and facets sitting over a hard crust formed in early December. While this structure is an active problem north of Terrace, including in the Ashman and Douglas areas, observations have been less conclusive near Shames and to the south.
The remainder of the snowpack is well settled and bonded. Treeline snow depth range from 200-280 cm.
Weather Summary
Sunday night
Partly cloudy. <15 km/h variable ridgetop wind. Treeline temperature around -5 °C
Monday
A mix of sun and cloud. 10 to 15 km/h variable ridgetop wind. Treeline high temperature -5 °C.
Tuesday
Mainly cloudy. Isolated flurries with minimal accumulations. 30 to 40 km east or southeast ridgetop wind, increasing. Treeline high temperature -7 °C.
Wednesday
Mainly cloudy. Isolated flurries with minimal accumulations. 20 to 40 km east or southeast ridgetop wind. Treeline high temperature -10 °C.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Be aware of the potential for large avalanches due to buried weak layers.
- Remote triggering is a concern; avoid terrain where triggering overhead slopes is possible.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
- In times of uncertainty, conservative terrain choices are our best defense.
Problems
Persistent Slabs
Weak grains over a buried crust presents a serious problem in the north of the region. Slabs have been easily triggered by riders on this interface, producing large and destructive avalanches.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Wind Slabs
Recent steady snowfall and elevated winds have been forming fresh wind slabs in open, leeward terrain. Surface avalanches have potential to step down to buried weak layers, resulting in large avalanches.
Aspects: North, North East, East, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 30th, 2024 4:00PM
