Clearly, we again find ourselves in a winter where persistent weak layers are playing a significant role in snowpack stability and avalanche hazard. And it's not over yet. While the likelihood of triggering an avalanche is significantly less than it was even a week ago and the number of avalanches being reported are down significantly in the last few days, the size of avalanches that are being triggered is remains quite large. This is typical of a PWL avalanche cycle and right about now is when people often make serious errors in judgement by assuming the problem is gone.
A couple of seasons ago, the CAC published a paper I wrote about the 2007-2008 PWLs. I have posted that paper on the CAC website at:
I used the above paper as the foundation for another one that discusses this year's problems and focusses on risk management advice. You can find this season's paper at:
http://www.avalanche.ca/cac/library/researchandarticles/PWLpaper0910
I urge everyone to exercise discipline and be vigilant. The layers we are dealing with are not going away any time soon. In some locations, they will almost certainly remain an issue right to the end of the season.
Karl Klassen
Mountain Guide
Mountain Guide
Public Avalanche Bulletins Manager
Canadian Avalanche Centre