Avalanche Forecast
Issued: Dec 19th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs, Persistent Slabs and Loose Dry.
Mark Herbison,
Excellent snow quality throughout the region!
Uncertainty surrounds the Dec 1 persistent weak layer and when / if it will become reactive. Assess the snowpack before committing to larger avalanche terrain.
Summary
Weather Forecast
Mainly sunny skies with cloudy periods for Monday as an Arctic High brings cold temps and 20-30km/hr Westerly winds. Tuesday will also be mainly sunny but will have isolated flurries with small accumulations of snow. More snow, 10-15cm, in the forecast for Wednesday.
Snowpack Summary
Excellent snow quality can be found throughout the Park with 40cm of new snow from the recent storm. The Dec 1 crust is ~10cm thick, buried a ranging depth of 50-100cm, and can be found up to 2300m. Facets observed above and below this crust, particularly in shallow snowpack areas at and just below tree line.
Avalanche Summary
A widespread natural avalanche cycle, up to size 3.0, occurred Saturday night as the tail end of the storm brought strong winds. The main issue for the day was managing the dry loose avalanches, which were sluffing fast.
Snowpack tests continue to give sporadic sudden results on the Dec 1 crust, particularly in shallower snowpack areas at tree line.
Confidence
Problems
Wind Slabs
Moderate Southerly winds may have redistributed the recent 40cm of new snow into pockets of slabs on lee features and in cross loaded areas at or near ridge line.
- Use caution in lee areas. Recent wind loading have created wind slabs.
- If triggered the wind slabs may step down to deeper layers resulting in large avalanches.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
The Dec 1st crust is buried by ~100 cm of snow. The crust is most reactive at tree line, but it is present below tree line and in the lower alpine. Be especially cautious in thinner snowpack areas, where it is more likely to be reactive.
- Avoid steep convexities or areas with a thin or variable snowpack.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Loose Dry
The bond between the new snow and older facetted snow may take a few days to strengthen. Expect loose dry avalanches in steep terrain to run fast and far.
- Use caution above cliffs and terrain traps where small slab avalanches may have severe consequences.
- Be careful of loose dry power sluffing in steep, confined or exposed terrain.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 20th, 2021 4:00PM
