Regions
Banff Yoho Kootenay.
Watch for local wind loading on Friday. New snow from the last few days is either sitting on a crust or on facets and we will be watching to see how these slab problems develop over the next few days. Currently we have limited observations.
Weather Forecast
Alpine winds will pick up from the SW Friday which will transport snow onto lee aspects. Only a few cm are expected Friday at upper elevations. A larger dump of snow is scheduled for Sunday but we've all heard that before.... Temperatures should stay in the -5 to -10 range.
Snowpack Summary
10-15cm over the last 24 hours and soft storm slabs were noted in alpine features Thursday. The alpine snowpack ranges from 50-90 cm across the region. 20-40cm has exists over the Halloween crust and facets which has been seen to 2700m. The snowpack is highly variable and wind transport was noted at ridgetop.
Avalanche Summary
Forecasters kicked off a size 1.5, 30-40cm deep soft storm slab over facets today in a steeper alpine moraine feature. It was sluggish due to the slab being so soft, but higher in the alpine these slabs could have more cohesion. Lake louise and Sunshine village were noting similar type avalanches.
Confidence
Due to the number and quality of field observations
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.