Avalanche Forecast
Issued: Dec 6th, 2019 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs, Loose Dry and Deep Persistent Slabs.
Mark Herbison,
Parks Canada
As the snow continues to fall, the weak faceted snowpack has reached threshold in many areas. Avoid exposure to avalanche terrain and allow the snowpack time to adjust (avalanche) to the new load.
Even small sloughs could knock you off an ice climb.
Summary
Weather Forecast
The storm continues, bringing another 5-15cm by Saturday night (less snow expected along the Eastern slopes). Winds will peak Saturday morning with gusts up to 60km/hr from the SW, then gradually tapering off as a cooler air system moves in. Expect an alpine high of -8 for Saturday and cooler on Sunday.
Snowpack Summary
40-50cm of new snow has fallen with moderate to strong SW winds, a storm slab is building in the Alpine down to Treeline. Below the storm slab, the snowpack structure is generally weak, consisting of facets and depth hoar. The Nov crust is up to 2400m and ~30cm up from ground. Snowpack depths at treeline are 80-130cm and deeper in lee areas.
Avalanche Summary
Numerous avalanches up to size 2.5 over the last 48 hours as the storm continues. These have been primarily wind/storm slabs in the new snow with isolated avalanches scrubbing deeper into the facets. Explosive control at the local ski areas has produced results up to Sz 2.0 in wind loaded areas.
Poor visibility today limiting observations.
Confidence
Problems
Storm Slabs
40-50cm of recent storm snow accompanied by strong SW winds have formed storm slab. Expect an increase in the size and reactivity of these as we receive more snow and wind over the next 24 hours.
- Use caution in the alpine and treeline. Storm snow is forming reactive slabs.
- If triggered the storm slabs may step down to deeper layers resulting in large avalanches.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Loose Dry
40-50cm of new snow has fallen, sloughing is a concern in steep terrain and gully features.
- Be careful of loose dry power sluffing in steep terrain.
Aspects: North, North East, East, South East.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
The snowpack structure under the new snow is weak, consisting of facets and depth hoar. If an avalanche is triggered it has potential to scrub down to deeper layers.
- Be aware of thin areas that may propogate to deeper instabilites.
- If triggered the storm slabs may step down to deeper layers resulting in large avalanches.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 7th, 2019 4:00PM
