The Dragon is Back – It’s a Facet Farm
It’s beginning to look a lot like… Christmas? The current state of our snowpack can best be described as uncharacteristically shallow and faceted, unless you are from the Rockies, in which case this is just normal.
To quickly summarize our winter up until now, November started with a decent snowfall and relatively cold temperatures. This was followed up by a couple of weeks of dry, cold and clear weather before the taps turned back on again in late November and early December. Depending on where in the province you are, this created a widespread persistent weak layer(PWL) of buried surface hoar and/or facets. You might hear this problem being referred to as the November 21st(or 22nd depending on when it got buried)PWL. This weak layer, although scary, hasn’t really matured for a number of reasons. The snow sitting above the weak layer has mainly been unconsolidated powder and the unusual cold spell has produced extensive and unstable faceting.
The projected rapid warming trend and significant new snow will change that in a big way. The drastic change in weather will increase the complexity of the snowpack. In the short term we will likely see storm slabs failing on this new persistent weak layer soon to be buried (Let’s call it the Christmas layer) but the new snow will also help the snow sitting above the November layer to settle into a proper slab which may or may not produce a natural avalanche cycle. If there is a natural cycle it will likely be big! Once this next set of storms clear up we will be left with a snowpack that may have two buried persistent weak layers as well as some very large facets at ground level. This is not preferred!
While the likelihood of triggering these deeper weaker layers is low(ish), the consequences of triggering it or having a smaller avalanche step down to these layers will become impressive. And scary! A lot of very experienced backcountry riders are seeing similarities to the 2002/03 winter season, which had many tragic consequences. Hopefully we can stay vigilant and err on the side of caution as we move into January.
Take good care.