Avalanche Forecast
Issued: Feb 11th, 2020 5:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
MBender,
Avalanche Canada
Little precipitation along with recent winds blowing from a variety of directions will keep wind slabs at upper elevations the main concern.
Summary
Confidence
High - Confidence is due to a stable weather pattern with little change expected.
Weather Forecast
Tuesday Night: Cloudy with clear periods. Light to moderate northwest wind. Alpine high temperatures around -10.
Wednesday: Cloudy with sunny breaks. Light moderate southwest wind. Alpine high temperatures around -7. Freezing level 800 m.
Thursday: Flurries, accumulation 5-10 cm. Light to moderate southwest and west wind. Alpine high temperatures around -7. Freezing level 900 m
Friday: Scattered flurries. Moderate west wind. Alpine high temperatures around -9. Freezing level 700 m.
Avalanche Summary
On Monday there were two reports of cornices failing naturally and triggering wind or storm slabs on slopes below to size 2.5 in the alpine on east and southeast aspects.
Reports of new avalanche activity on Sunday were of skier or rider triggered wind slabs to size 1 and 1.5 in the alpine and at tree line.
There was a report of a remotely triggered (from a distance) size 2.5 deep persistent slab avalanche on Saturday. It was 130 cm deep and triggered in a shallow area at 2300 m on an east aspect.
Snowpack Summary
20-60 cm of snow accumulating through the last week overlies previously wind-affected snow at higher elevations, with diminished depths of about 20-30 cm above a widespread melt-freeze or rain crust up to about 1700 metres. This new snow has been redistributed by winds blowing from a variety of directions.
The mid and lower snowpack are generally well settled, however an aging weak layer of surface hoar from late December, currently buried 70 to 150 cm deep, has shown surprisingly long-lived instability on slopes between 1700-2400 m (above the crust elevation and below the most wind-affected elevations), warranting increased caution around steeper slopes in this elevation band, particularly in the southern half of the region. A facet/crust layer from November may be found near the ground in shallower snowpack areas and has been suspected of being the cause of sporadic very large avalanches releasing in the past 10 days.
Terrain and Travel
- Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
- Recent wind has varied in direction so watch for wind slabs on all aspects.
- Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
Problems
Wind Slabs
Recent snowfall combined with shifting winds have built wind slabs on a variety of aspects.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
There are two deeply buried weak layers that are suspected of being the cause of sporadic very large avalanches releasing in the past 10 days. A layer of buried surface hoar may persist in the south of the region at and below treeline. A layer of facets near the base of the snowpack can be found throughout the region in the alpine. Although it is unlikely to trigger these layers, doing so would result in a very large and destructive avalanche.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Feb 12th, 2020 5:00PM
