Avalanche Forecast
Issued: Jan 4th, 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
Storm slabs will likely be reactive to human triggering, especially in wind loaded areas. Watch for signs of instability such as whumpfing, cracking and recent avalanches.
Concern remains for persistent weak layers, which are best managed through conservative terrain choices.
Summary
Confidence
Moderate - Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.
Weather Forecast
MONDAY NIGHT - Flurries, 10 cm / light to moderate west wind / alpine low temperature near -9Â
TUESDAY - Mainly cloudy with a few flurries / light southwest wind becoming moderate south in the afternoon / alpine high temperature near -7Â
WEDNESDAY - Mainly cloudy with a few flurries, around 5 cm / moderate southwest wind, easing in the afternoon / alpine high temperature near -6 / freezing level 1300 m
THURSDAY - A mix of sun and cloud / light northeast wind / alpine high temperature near -5Â
Avalanche Summary
On Sunday, numerous natural, human and explosive triggered storm slab avalanches up to size 3.5 were reported in the region.Â
On Saturday, numerous natural and human triggered storm slabs to size 1 at treeline and below were reported.
Recently formed storm slabs will be most reactive in wind affected terrain at treeline and above.
Snowpack Summary
10-20 cm of new snow brings recent storm snow totals to around 60-70 cm. Recent strong southwesterly winds have formed widespread storm slabs at all elevations.
Two persistent weak layers buried in early/mid Dec. are now 110-180 cm below the surface. The form and distribution of these layers are HIGHLY VARIABLE and have created conditions that can vary 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. As a result, diligent investigation of the snowpack is required to get a handle on local conditions.
Terrain and Travel
- Avoid freshly wind loaded terrain features.
- Be aware of the potential for large avalanches due to the presence of a persistent slab.
- Storm slabs in motion may step down to deeper layers resulting in large avalanches.
- Uncertainty is best managed through conservative terrain choices at this time.
Problems
Storm Slabs
New snow and recent strong winds have created storm slabs that will likely still be easy to trigger, especially in wind loaded areas and at higher elevations.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
Two persistent weak layers buried in early/mid-December are now 100 to 180 cm below the surface. The form and distribution of these layers are HIGHLY VARIABLE and have created conditions that can vary significantly from one valley to the next.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Jan 5th, 2021 4:00PM
