Avalanche Forecast
Issued: Jan 5th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Persistent Slabs.
kdevine,
Avalanche Canada
Lots of recent fresh snow, strong southwest winds, and a buried weak layer means that human triggered avalanches remain likely for now. Choose conservative terrain.
Summary
Confidence
Moderate - Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.
Weather Forecast
TUESDAY NIGHT - Mainly cloudy with flurries, 5-10 cm / strong southwest wind / alpine low temperature near -7Â
WEDNESDAY - Mainly cloudy with a few flurries, 5-10 cm / strong southwest wind / alpine high temperature near -6 / freezing level 1400 m
THURSDAY - A mix of sun and cloud / light east wind / alpine high temperature near -7Â
FRIDAY - Mainly sunny / light northeast wind / alpine high temperature near -2, slight temperature inversion
Avalanche Summary
Recent storm slabs will likely be easiest to trigger in wind loaded areas, as well as in the trees where they may rest on a buried surface hoar layer.
A few size 1 storm slab avalanches were reported on Monday.
It is notable that there were several human triggered avalanches reported at lower elevations in the neighboring Glacier National Park region on Monday. These avalanches highlight the potential to trigger avalanches in the trees. Reports of these can be viewed here, here, and here.
On Sunday, numerous explosive triggered storm slab avalanches up to size 3.5 were reported just west of Revelstoke.
On Saturday, a skier triggered a size 2 slab avalanche near the Gorge area. See the excellent MIN report here.
Snowpack Summary
20-40 cm of recent new snow brings storm snow totals to around 30-75 cm. Strong southwest winds overnight have likely formed widespread storm slabs. The storm snow sits on a weak layer of surface hoar that was buried around Christmas. This layer continues to be of concern, mainly at treeline and below treeline.
Two persistent weak layers buried in early/mid-December are now down about 90-150 cm. The form and distribution of these layers are highly variable and conditions may differ significantly from one valley to the next. The first layer has been primarily reported as small surface hoar. The next layer has been reported as a thin freezing rain crust, surface hoar, or thick rain crust depending on elevation and location. This layer also remains a concern, primarily at treeline and below.
Terrain and Travel
- Avoid freshly wind loaded terrain features.
- Storm slabs in motion may step down to deeper layers resulting in large avalanches.
- Be aware of the potential for large avalanches due to the presence of a persistent slab.
- Uncertainty is best managed through conservative terrain choices at this time.
Problems
Storm Slabs
New snow and recent strong winds have created widespread storm slabs that are still likely to be triggered by humans in many areas.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
Two persistent weak layers buried in early/mid-December are now 90-150 cm below the surface. The form and distribution of these layers are highly variable and may vary significantly from one valley to the next, and between elevations bands.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Jan 6th, 2021 4:00PM
