Avalanche Forecast
Issued: Dec 12th, 2019 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs and Storm Slabs.
ahanna,
Avalanche Canada
New snow sitting on a layer of surface hoar may be a recipe for thin but reactive storm slabs over the next few days.
Summary
Confidence
Moderate - Uncertainty is due to the limited number of field observations.
Weather Forecast
Thursday Night: Flurries accumulating up to 5 cm. Alpine low -6, moderate southwest wind.
Friday: Flurries with trace accumulation, alpine temperature -4, light northwest wind.
Saturday: Mainly cloudy, isolated flurries with trace accumulation, alpine temperature -8, light northwest wind.
Sunday: Mainly cloudy, isolated flurries with trace accumulation, alpine temperature -10, moderate northwest wind.
Avalanche Summary
Reports from today included sloughing and loose dry size 1 avalanches in the storm snow, as well as a persistent slab avalanche triggered remotely by a helicopter. It is important to keep in mind the potential for large, persistent slab avalanches.
Snowpack Summary
A total depth of 150-250 cm of snow sits in the alpine in central parts of the region. 5-10 cm of new snow has covered a layer of feathery surface hoar crystals that were observed at all elevations throughout the region. We will be keeping an eye on this layer as it gets buried further.
The primary layers of concern at this time are a couple of weak layers in the mid snowpack, formed in late November and early December which can be found most notably at treeline, and may present as surface hoar, a crust, facets or a combination, depending on elevation and aspect. These types of weak layers are typical failure planes, on which overlying slabs can start to slide and produce avalanches.Â
Below, a variety of facet/crust layers from late October are buried near the bottom of the snowpack and are not active with respect to avalanche activity at this point in the season.
Problems
Persistent Slabs
A couple of weak layers formed in late November and early December, sitting 60-120 cm below the surface, may present as surface hoar, a crust, facets or a combination, depending on elevation and aspect. They can most likely be found in areas sheltered from the wind, but open to a view of the sky, such as near treeline.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Storm Slabs
Moderate winds interacting with the 10-20 cm of new snow on Thursday have likely created pockets of deeper storm slab in lee features.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 13th, 2019 5:00PM
