Briefly, there has been a layer of surface hoar there that was buried Dec 30. No real activity until the last couple of days because it was under a shallow soft slab. Over the last few days there was about 70cm of new snow, but still not really high density and no remarkable slab formation except for in a few really wind-affected areas. Yesterday the patrol did some bombing and the only result was a sz2.5 on a steep E aspect that failed about 10cm above the surface hoar. All in all not too much to worry about except for the large amount of new storm snow.

Friday and Saturday the hill got absolutely pounded, so naturally today people were looking to ski some of the easily accessible slackcountry. A free day pass was dangled in front of me, so I drove down to Golden to join a Kicking Horse patroller and one other for the day. The following names will mean something if you’re familiar with the hill, but don’t really matter to the narrative. We started off by dropping into Superbowl (one bowl South of the gondola top). Because it’s a moderate bootpack up about 200m vertical metres there were already a few tracks put in. We skied that (a S aspect) with no incident, then skinned up the other side of the bowl for some more low angle goodies. A quick profile showed the sfc hoar down about 60cm and pole probing showed intermittent wind slab on our way up the shoulder. Skiied down and still no fast sluffing, no settlements or cracking. Rode an East facing slide path to the base for good measure and no results.

In the early afternoon we headed across the bottom of Feuz bowl and into Rudy’s bowl (north of the resort) and up onto the next ridge looking into the Molars. Plan was to ski one of the N-facing gullies which the other two in my group have skied numerous times, but not yet this season. We noted some evidence of wind transport and selected the lowest-angle gulley as the best descent. Still, the top was quite open and about 35 degrees, and more importantly funnelled down into a bit of a trap. Despite a cornice cut and two ski cuts producing no results, we decided against skiing down the gut and sent one down a more conservative line that avoided the upper (likely wind-loaded) bowl. Check out the pic at this point:

The skier cut a small feature on the righthand side of the path. Turned out that the small feature was shallow snow on top of some buried Christmas trees. He was briefly caught as the slab released just above him, but got out fairly quickly. Two of us found a safe way down to  the bed surface and found a crown 60-80cm deep, to ground. The snow depth elsewhere was 1.5-2m (a little odd..). The angle of the gulley where the slab released was in the low 30s at most. In the end the slab was about 10m x 30m and the debris ran for about 300m and was about 1-1.5m deep at the toe.

After getting out of the way and discussing what just happened, we came up with a couple of factors:

1.       Ski cut on buried shallow feature: A common feature in many skier-triggered avalanches, and as is often the case, there was no evidence beforehand that this was in fact an area of shallow snow

2.       No anchoring by vegetation. The slab essentially slid on smooth bedrock. Based on the slope angle and the cohesiveness of the overlying snow (before it slid) I wouldn’t usually expect something to run this far and fast….unless there’s a nice smooth sliding surface

From the bottom we could see two adjacent gullies, slightly steeper, that had 7-10 sets of tracks down them from today. No fast sluffing or sliding on either of those. We were a little perplexed about the depth of snow in our slide until..

3.       We found out from patrol that this path had slid to ground numerous times already this season; in the words of one, “that path isn’t representative of our snowpack”

I think this case is illustrative however because of the information that we didn’t know. Had we known about the lack of anchoring vegetation (present in many adjacent gullies) and the fact that the gulley had slid numerous times this season, we probably would’ve done something different.

What I learned from today’s incident that no matter how thorough your observations, how familiar with the area your partners are, there will be potentially important pieces of information that you don’t find out until it’s too late. In this case I think this risk was mitigated somewhat by the fact that we had two potential rescuers in a safe area had the first skier gone for a ride and been buried, but the fact remains that we got caught with our pants down.