I hope this finds Everyone keeping well.....
I went up into the hills today to make some observations because the clouds have begun to clear from the mountains and I wanted to know what has changed. This is what I noted:
The debris from the older natural slab avalanches, that had run on the northwest side of Oboe (facing Whistler Mountain), was still evident. These avalanches were large and released on steep, rocky, and cross-loaded terrain at treeline elevation. It is still possible to trigger avalanches in this kind of terrain or on these types of features. Cross-loaded terrain means that the winds sweep across the face of the slope instead of down the slope. The nature of the snowcover on terrain like this is much more difficult to predict because there are areas where the snowcover is deeper and then areas where it is much shallower. The problem is that these differences are not often perceptible and since we're currently dealing with a hazard that has been, in addition to other types of terrain, producing large avalanches from shallow places, then we have to be very cautious. Essentially, shallower places make it easier to trigger that weaker layer that's living just above the early-December crust!
So, I went out today to measure if anything had changed with this weak layer of sugary snow (called facets) that sits on the early-December crust which is buried deeply (or not so deeply- depending upon the terrain!) in the snow. This faceted snow is generally much slower to gain strength....... and that was evident again today; the layer continues to show that, if it were triggered in the wrong terrain, that there is a greater likelihood of widespread slope failure. Makes you very humble when you consider that there is a lot (up to 160cm in treeline places) of dense snow sitting on top of that layer.
The forecast tells us that our on-mountain temperatures will warm significantly over the next few days. Expect the avalanche hazard to rise along with the temperatures.
And although there haven't been as many alpine observations being noted recently on the South Coast MCR, please don't forget that this instability in the snowpack is not limited to just treeline locations.... it lives in the alpine snowpack, too. Rocky, steep, and large alpine slopes are incredibly suspect.
Terrain with no exposure to avalanches continues to be a prudent decision, especially with the forecasted warming ahead.....
Wishing Everyone a safe and pleasant mid-January,
Dale Marcoux
Assistant Ski Guide
ACMG Member