Avalanche Forecast
Issued: Jan 11th, 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
Avalanche hazard will gradually rise over the day and into Tuesday night as new snow and wind form fresh wind slabs at upper elevations.
If you see more than 20 cm by the end of the day, treat avalanche danger as CONSIDERABLE at elevations with wind blowing the snow around.
Summary
Confidence
Moderate - Uncertainty is due to the timing, track, & intensity of the incoming weather system.
Weather Forecast
Monday night: Flurries, trace, moderate to strong southwest wind, freezing level 600 m.
Tuesday: Snow, 5-15 cm, strong southwest wind, alpine high -4, freezing level 1200 m.
Wednesday: Snow overnight then clearing, 10-20 cm, moderate northwest wind, alpine high -9, freezing level 1200 m.
Thursday: Sunny, light southwest wind, alpine high -7, freezing level 700 m with a weak inversion setting up.
Avalanche Summary
Isolated wind slabs have been occasionally reactive to skier traffic, limited to size 1.
Snowpack Summary
New snow falls on wind affected surfaces at upper elevations, surface hoar in wind sheltered areas and a thin crust on solar aspects. Winds are likely redistributing new snow into wind slabs and growing cornices.Â
A couple of persistent weak layers exist in the upper to mid snowpack:
- The upper layer, found 50-80 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 will add additional load to these layers and may shed some light on whether they will remain a concern.
Terrain and Travel
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Wind slabs are most reactive during their formation.
- Dial back your terrain choices if you are seeing more than 20 cm of new snow.
Problems
Wind Slabs
New snow and strong winds are likely forming fresh wind slabs in leeward terrain features at upper elevations.
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, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
A couple of weak layers exist in the mid snowpack, buried 50-80 cm and 90-150 cm below the surface. They are highly variable in form and distribution and have not been associated with avalanche activity in recent 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 12th, 2021 4:00PM
