Avalanche Forecast
Regions: Northwest Coastal.
Warming and solar radiation could weaken the snowpack, perhaps increasing the chance of triggering slab avalanches on steep open slopes.
Confidence
Moderate - Uncertainty is due to how the snowpack will react to the forecast weather.
Weather Forecast
WEDNESDAY NIGHT: Clear skies, moderate wind from the southwest, mild temperatures with above freezing temperatures between 1000 and 2000 m.
THURSDAY: Clear skies, moderate wind from the southwest, freezing level drops from 2000 to 1000 m throughout the day.
FRIDAY: Storm arrives with cloudy skies and 5-15 cm of snow, strong wind from the south, freezing level fluctuates between 500 m and 1000 m with treeline temperatures around -2 C.
SATURDAY: Stormy weather continues with another 15-25 cm of snow, strong wind from the south, freezing level fluctuates between 500 m and 1000 m with treeline temperatures around -2 C.
Avalanche Summary
Warm sunny weather since Monday has resulted in a few loose wet and glide slab avalanches. The most concerning avalanche activity has been a string of persistent slab avalanches over the past week. These have occurred on a 30-50 cm deep layer of surface hoar in southern parts of the region around Terrace and Stewart. This has included both natural avalanches (last report from Tuesday) and human-triggered avalanches (last report from Sunday). The photos of the avalanche in this MIN report at Clague are good examples of the type of treeline elevation terrain where this problem can be found. We are uncertain whether the persistent slab problem will remain reactive throughout the current melt-freeze cycle and into the weekend.
Snowpack Summary
The snow surface is undergoing a spring-like melt-refreeze pattern. Warm sunny weather will likely melt the surface in most places except high north-facing terrain. The snowpack is likely capped by a hard crust in most areas, which has helped create a strong settled snowpack. The exception is a 30-50 cm deep surface hoar layer that could still be reactive, especially at treeline elevations in the Terrace and Stewart areas.
Terrain and Travel
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
- Back off slopes as the surface becomes moist or wet with rising temperatures.
- When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.
Avalanche Problems
Persistent Slabs
It's possible to trigger avalanches on a 30-50 cm deep surface hoar layer that has recently been reactive near Terrace and Stewart. Most avalanche activity has been at treeline elevations, but we are still uncertain about the spatial distribution of this problem.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible - Likely
Expected Size: 1.5 - 2
Loose Wet
Warm sunny weather will likely trigger small loose wet avalanches on steep south-facing slopes.
Aspects: South East, South, South West.
Elevations: All elevations.
Likelihood: Possible
Expected Size: 1 - 1.5