Regions
Banff Yoho Kootenay.
With large amounts of snow currently showing in forecasts, we expect avalanche activity to begin Friday and continue through the weekend. TH
Weather Forecast
A powerful low will exert its influence over the region beginning Thursday evening. Accumulations of 50-100 cm of snow at treeline, high winds, and freezing levels rising to near 2000 m have been forecast to appear by the time the system passes on Sunday. With the heavy loading expected, an avalanche cycle will likely begin on Friday.
Snowpack Summary
35-45 cm of unconsolidated snow exist at treeline elevations throughout the forecast area. A 5mm layer of surface hoar that was reported in some areas has been buried by several cm of new snow yesterday (November 11 surface hoar). Some soft wind slabs exist at higher alpine elevations.
Avalanche Summary
Over the past five days slabs and loose snow avalanches (up to size 2.5) have been triggered and are running naturally from alpine features. Tuesday, at Bow Summit, a size 1.5 avalanche was remotely triggered on the ground, and on the Wapta a group remotely triggered a size 2 on Mt. Olive.
Confidence
Intensity of incoming weather systems is uncertain on Thursday
Problems
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.
Loose Dry
Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.