Recent avalanches have failed on a deeply buried weak layer. Although the chances of triggering a deep slab are dropping, the consequences remain high.
Summary
Confidence
Fair - Due to the number of field observations
Weather Forecast
Mainly clear cool weather is expected until late Monday, when a system is expected to brush up against the coast and bring light snowfall. Freezing levels are near 1000m. Light to moderate SE winds.
Avalanche Summary
A natural cycle up to size 3 was observed throughout the recent storm. These included wind slabs and storm slabs, primarily at alpine elevations; and loose wet and wet slab avalanches at treeline and below. Some of these events failed on a crust /facet layer buried in late November and were more than 1 metre deep. On Thursday night a slab failed naturally in terrain that had previously been controlled with explosives, 1.5-2 m deep, with good propagation on the crust/facet layer. A second 1.5m deep slab also failed naturally on the same layer on Friday. On Saturday, a vehicle remotely triggered yet another slab 1m deep, on a north-facing slope in the alpine. Check out some recent photos here: http://www.wayneflannavalancheblog.com/.
Snowpack Summary
The recent prolonged storm dropped 100-200mm of water, with fluctuating freezing levels bringing rain at times to alpine elevations. Snow also accumulated above treeline, leading to deep wind slabs. Now the storm is over, storm slabs and wind slabs may remain problematic for a day or two. However, my bigger concern is a buried crust/facet layer which formed in November and is now down 1-2 m. This woke up with the recent storm snow loading and has the potential for deep slabs and wide propagations, and does not inspire huge confidence. The likelihood of triggering this beast is dropping, however the consequences remain high.
pgoddard,
Avalanche Canada
