Avalanche Forecast
Issued: Dec 13th, 2019 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Persistent Slabs.
ahanna,
Avalanche Canada
20-30 cm of new snow rests on a layer of surface hoar. Expect it to become touchy as it settles into a storm slab in the mild temperatures. Watch for shooting cracks and electric propagation, especially near openings in the trees.
Summary
Confidence
Moderate - Uncertainty is due to the limited number of field observations.
Weather Forecast
Friday Night: Cloudy with clear periods and isolated flurries with trace accumulation. Alpine low -9, light northwest wind.
Saturday: Cloudy with sunny periods, alpine temperature -8, light northwest wind.
Sunday: Cloudy with sunny periods and with isolated flurries with trace accumulation, alpine temperature -10, light to moderate northwest wind.
Monday: Mix of sun and cloud, alpine temperature -8, moderate west wind.
Avalanche Summary
Reports from Thursday 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 150-300 cm of snow sits in the alpine in central parts of the region. 15-30 cm of new snow has covered a layer of feathery surface hoar crystals that were observed at all elevations throughout the region. The new snow can be expected to gain cohesion and settle into a slab in the mild temperatures, especially at treeline and below.
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.
Problems
Storm Slabs
New snow sitting on a layer of surface hoar may be a recipe for small loose dry avalanches and thin but reactive storm slabs. You may find deeper pockets 30+ cm of storm slab in lee features.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
A couple of weak layers formed in late November and early December, sitting about 1 m below the surface, may present as surface hoar, a crust, facets or a combination of those, 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
Valid until: Dec 14th, 2019 5:00PM
