Just back yesterday from a week of hut based ski touring in Kokanee Glacier Provincial Park. My seventh trip there in as many years. Now, likely to be my last. Each week has been different, with different snow conditions, different weather, (slightly) different people, and different tours and objectives accomplished.
The best week we had was 2010, when we had good weather, good stability, and were skiing in a group of three, all strong skiers. We skied big days and skied some lines that I had been looking at for years, waiting for conditions to be right. The worst year was 2007 when a Pineapple Express rolled through on our second day (first full day). Fifty millimeters of rain saturated the snowpack and there was a widespread avalanche cycle. After that, the temperature plummeted to -17 Celsius, and the snow surface froze into a deadly icy crust.
From this year, I have mixed feelings. Snow quality was generally good and plentiful. Weather was generally bad - which gave rise to the plentiful snow. Stability was generally fair to poor. A mixed bag of crusts, surface hoar, near surface facets was down 30 cm, then 40 cm, then, suddenly, 90 cm, and a widespread avalanche cycle ran through the area. After the natural activity settled, we were still concerned with skier triggering, and, rapid loading continued with heavy snow and strong winds for multiple days in a row.
Overall, we skied very conservatively and cautiously. We had no involvements during the week, which was possibly one of the only weeks out of my seven when there hasn't been at least one skier accidental avalanche - some of which I have triggered.
On a couple of days we pulled the pin on planned descents as, when we got to the top of the runs, we found them too steep and wind-loaded to commit to - and they were committing slopes. On a couple of days we skied very low angle conservative terrain while avariciously ogling steeper slopes nearby. On all those days I came home wondering if we could have skied the slope and not triggered an avalanche.
One of the issues commonly bandied around in discussions of skier triggered avalanches is the influence of so called "positive feedback". We go out, either consciously or unconsciously make decisions to ascend/descend various slopes and do NOT get caught in an avalanche. On most occasions this is simply because the snow is stable most of the time. But, we make the assumption that we did not get caught in an avalanche because we made good decisions. In fact, we may have made stupendously bad decisions and got lucky, simply because snow, as previously stated, is stable most of the time.
This is the opposite (in a way) of my feelings at the end of each ski day. Did I make good decisions or could I have skied X, Y or Z slope and found the snow stable? Was I, in fact, making a stupendously bad decision by not skiing a slope that I could have skied with complete safety?
In either case, we'll never know. I may have avoided an avalanche by good decision making or by luck. I may have forgone skiing a certain slope that would have been perfectly safe.
As one old bold mountaineer once said, "everything was good until it wasn't".
Remotely triggered, 90 cm deep, 30 degree well supported short slope