Avalanche Forecast
Issued: Mar 19th, 2017 5:55PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs, Wind Slabs and Loose Wet.
tim haggarty,
Avalanche Canada
Avoid exposure to avalanche terrain: large avalanches can reach valley bottom trails. Although activity should taper in the wake of this weekend's storm, as the sun comes out Monday it would be wise to watch what happens from a distance.
Summary
Weather Forecast
A ridge has established itself over British Columbia in the wake this weekend's storm and as this pushes into the region clearing will result, even if briefly, Sunday night. Despite a return to -10C temperatures at treeline through Monday night, expect solar inputs to be significant before freezing levels climb back up to 1800m late Tuesday.
Snowpack Summary
15 to 30cm of storm snow combined with moderate to strong S and W winds this weekend have built superficial wind and storm slabs. This new load combined with 40 to 80 cm of snow that has fallen in the last two weeks continues to overload the deep basal facet layers in all corners of the region. Rain to 2200m Saturday created moist to wet snow.
Avalanche Summary
New evidence of Natural activity has been observed today on patrols around the park and explosive control work has produced massive results in the Lake Louise and Yoho regions with impressive propagation. Large avalanches that initiate in the alpine and at treeline continue to entrain moist snow BTL attaining large destructive potential and reach.
Confidence
Problems
Persistent Slabs
Several buried weak layers in the middle of the snowpack have become reactive again as they have been overloaded by recent snow and rain. Large avalanches are reaching historical run outs and crossing cross country ski trails.
- Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.
- Be wary of slopes that did not previously avalanche.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Wind Slabs
Wind slabs over 1m deep exist at higher elevations and in wind affected areas near treeline. These slabs react easily to tests and continues to produce avalanches. Correspondingly, cornices have grown significantly and are fragile.
- Pay attention to overhead hazards like cornices which could easily trigger persistent slabs.
- Be aware of the potential for wide propagations.
Aspects: North, North East, East, South East, South, South West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Loose Wet
With freezing levels in excess of 2200m Saturday, the snowpack at lower elevations lost strength. As this snow refreezes, moist snow remains under surface crusts which large avalanches from upper elevations can entrain to reach surprising distances.
- Use extra caution on slopes if the snow is moist or wet.
- Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.
Aspects: All aspects.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Mar 20th, 2017 4:00PM
