Avalanche Forecast
Issued: Dec 5th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
GS,
Avalanche Canada
The persistent slab, hard windslabs and wind-affected snow conditions continue to be the story for the week as evidenced by Sunday's close call on Wolverine Ridge. The odd natural avalanche has occurred, but human triggering is likely on steep slopes.
Summary
Confidence
Moderate
Avalanche Summary
An explosive triggered a size 2 hard slab at Lake Louise, and a cornice fell and triggered a size 2 at Sunshine, both avalanches occurred in steep, alpine terrain. Yesterday a near-miss occurred in the Lake Louise backcountry with a persistent slab at treeline. Small sluffs of low-density surface snow should be expected in gullies.
Snowpack Summary
The snowpack surface is generally wind-blasted in most places with a few cm of low-density new snow from the past 24 hours. This has produced hard windslabs that can fail with the right trigger in the right place. Any avalanche triggered now will likely step down 20-40 cm into the persistent layers and become larger.
Weather Summary
An arctic ridge of high pressure over BC fights with a low-pressure system over Alberta, bringing cold temperatures and light snow for the next 24 hours. On Tuesday, expect 2-5 cm (more to the east), temperatures ranging from -10 to -15 and winds from the NW before a clearing trend for Wednesday.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Watch for areas of hard wind slab on alpine features.
Problems
Wind Slabs
Hard windslabs exist 15-30cm deep in alpine areas. They may be triggered on their own, but have been prone to stepping down to the persistent layer of facets near the ground.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
A 20-60 cm slab sits over a persistent weak layer of basal facets, buried sun crusts, or isolated pockets of surface hoar. This layer is unpredictable and will be around for some time to come.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 6th, 2022 4:00PM
