Avalanche Forecast
Issued: Jan 10th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
ahanna,
Avalanche Canada
A bit of new snow with strong wind will keep upper elevation wind slabs fresh on Monday. They will likely be thin but reactive, especially to human triggers.
Summary
Confidence
High - The number, quality, or consistency of field observations is good, and supports our confidence.
Weather Forecast
Sunday night: Flurries, trace, light to moderate southwest wind, freezing level valley bottom.
Monday: Flurries, up to 5 cm, strong southwest wind, alpine high -6, freezing level 900 m.
Tuesday: Flurries, up to 5 cm, strong southwest wind, alpine high -6, freezing level 900 m.
Wednesday: Snow, 10-20 cm, strong southwest wind, alpine high -3, freezing level 1200 m.
Avalanche Summary
A few reports of mostly minor solar triggered avalanches came in Saturday afternoon, mostly less than size 1 but up to size 2.Â
Some cornice control work was conducted across the region Saturday. Explosives produced a size 1.5 cornice which did not trigger a heavily skied slope below. A vehicle-triggered cornice drop tested a north facing alpine slope below, triggering a size 2 wind slab which did not step down to deeper layers.
Snowpack Summary
Small amounts of new snow fall on surface hoar in many areas and a thin crust on solar aspects. Previous moderate to strong winds have created variable wind effect at wind exposed elevations.Â
A couple of persistent weak layers exist in the upper to mid snowpack:
- The upper layer, found 40-80 cm down, is a spotty layer of surface hoar at treeline and below.Â
- The lower layer, found 90-150 cm down, is widespread and can present as surface hoar and/or a crust.
Avalanche activity on these layers has dwindled since last week and snowpack tests results have been moderate to hard planar, but still showing some propagation. Incoming snowfall in the forecast for this week will add additional load to these layers and may shed some light on whether they will remain a concern.
Terrain and Travel
- Fresh wind slabs will likely form throughout the day, diligently watch for changing conditions.
Problems
Wind Slabs
Previous snow and wind have created deep pockets of wind slab in lee terrain features at upper elevations. These were very reactive before the weekend and may remain sensitive to human triggers.
Cornices have also been growing. A cornice fall is a large load that can trigger avalanches on the slope below.
Aspects: North, North East, East, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
A couple of weak layers exist in the mid snowpack, buried 40-80 cm and 90-150 cm below the surface. They are highly variable in form and distribution and there has not been any associated avalanche activity in the last few days. Incoming snowfall in the forecast for this week will add additional load to these layers and may shed some light on whether they will remain a concern.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Jan 11th, 2021 4:00PM
