Avalanche Forecast
Issued: Apr 7th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Cornices.
astclair,
Avalanche Canada
Watch for isolated pockets of wind slab at upper elevations and minimize your exposure to cornices.
Summary
Confidence
Weather Forecast
Wednesday night: Clearing overnight, moderate northwest wind, treeline temperatures around -8 C and freezing level dropping to valley bottom.
Thursday: Increasing cloud, flurries arriving late in the day, winds becoming southwest and increasing to strong, treeline temperatures rising to -3 C, freezing level rising to 500 m.
Friday: Overcast, 15-25 cm of snow, strong southwest wind, treeline temperatures -2 C, freezing level rising to 700 m and dropping to valley bottom overnight.
Saturday: Mix of sun and cloud, isolated light flurries, moderate west wind, treeline temperatures -3 C, freezing level rising to 500 m and dropping to valley bottom overnight.
Avalanche Summary
In the aftermath of the weekend storm, there have been reports of several natural and explosive-triggered avalanches (size 1.5-2) in the recent snow triggered by incremental loading, warming, and wind-loading. Below 600 m, there have been observations of loose wet avalanches and one instance of a large (size 2) wet slab that failed to the ground from a steep, shallow feature.
Large natural and explosive triggered glide slab avalanche activity has been ongoing for the past few weeks. Glide cracks releasing as full depth glide slab avalanches are extremely difficult to predict. Best practice is to avoid slopes with glide cracks.
Snowpack Summary
Moderate winds at upper elevations may continue to build wind slabs in lee features, especially where the wind is redistributing dry snow. Below 1000 m, the snow surface will likely refreeze and form a crust.
Over the past week, 40-60 cm of snow has fallen at upper elevations. Sun crusts may be found on sun-exposed slopes. Cornices are large, looming, and capable of triggering large avalanches when they fail. Previous weak layers are now deeply buried and have not resulted in any recent avalanches.
At lower elevations, the recent snow has mixed with rain, forming a crust in the freezing temperatures overnight.
Terrain and Travel
- Expect slab conditions to change drastically as you move into wind exposed terrain.
- Watch for wind-loaded pockets especially around ridgecrest and in extreme terrain.
- Avoid exposure to slopes that have cornices overhead.
- Stay off recently wind loaded slopes until they have had a chance to stabilize.
Problems
Wind Slabs
Moderate winds may continue to build reactive slabs in lee features, especially where the wind is redistributing dry snow.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Cornices
Cornices are large and looming along many ridgelines and have likely grown with the recent snow and wind.
Aspects: North, North East, East, West, North West.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Apr 8th, 2021 4:00PM
