South Columbia

Though avalanche danger may be decreasing, the potential exists to trigger persistent slab avalanches. While these avalanches are becoming less likely, the consequences are high. The uncertainty associated with complex snowpacks is best managed with conservative terrain choices.

THURSDAY NIGHT - Cloudy with clear periods / light to moderate southeast wind / alpine low temperature near -5

FRIDAY - A mix of sun and cloud / moderate southeast wind / alpine high temperature near -5 

SATURDAY - A mix of sun and cloud / light southeast wind / alpine high temperature near -7 

SUNDAY - A mix of sun and cloud / light southeast wind / alpine high temperature near -6

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.

At the time of publishing, there was one human triggered size 1.5 storm slab avalanche reported near Revelstoke on a southerly aspect at about 2300 m on Thursday.

On Wednesday, there were three natural persistent slab avalanches size 2.5-3 reported in the region on northerly aspects in the alpine. Two of these were reported to have run on the early December persistent weak layer. There were also numerous reports of human and explosives triggered storm and wind slab avalanches size 1-2.

Numerous natural, human, and explosives triggered avalanches size 1-3 were reported in the region on Tuesday. Of these, many were storm and wind slab avalanches, however, it is notable that some of the larger ones were reported to have run on the early December persistent weak layer. These ones occurred on northeast through south aspects in the alpine.

Numerous size 1-2 human and explosives triggered storm and wind 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 natural, human and explosive triggered storm slab avalanches up to size 3.5 were reported in the region. Check out this MIN report from Sunday of an avalanche below treeline on Begbie Shoulder near Revelstoke.

Around 40-80 cm of recent fresh snow now sits on a weak layer of surface hoar that was buried around Christmas. This layer is most prevalent at treeline and below treeline. Previous moderate to strong winds have likely redistributed the new snow, creating storm and wind slabs.

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 may 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. This layer also remains a concern.

• Avoid freshly wind loaded terrain features.
• Approach steep open slopes at and below treeline cautiously, buried surface hoar may exist.
• 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.