There was a close call early this season. Two backcountry skiers were in the Jones Pass area. They had made several runs in an upper bowl near the pass. On their last run, they moved to a smaller untracked bowl. They found "bomber hard" snow, and were unable to break through when they jumped on it. The first skier descended along the skier's left side (looker's right) and waited at the bottom of the slope just before the end of the snow.
The red line indicated the aproximate area of the avalanche.
A photo of the bowl and avalanche slope, taken before the final run.
The second skier entered the slope further to skier's right. The skier triggered an avalanche on his third turn. The fracture propagated very quickly across the slope. The skier was able to struggle to the skier's right of the avalanche, and was almost free of the tumbling debris. Another avalanche ripped out along the right flank, catching the skier again. The combined avalanches carry the skier 2/3 of the way down the slope and, fortunately, he was deposited uninjured on the surface of the debris.
The first skier watched in horror as two hard slab avalanches sped towards her. She had time to hunker down, and then was overrun by the avalanche. She, too, was fortunate and not buried or injured.
The avalanches occurred above treeline in a cross loaded pocket around 12,000, on a northeast to east-northeast aspect. The party described the slope as "38 degrees," the perfect angle for avalanches. The first avalanche was about 75 feet wide, and up to 18 inches deep. The second avalanche was similar in size, but ran to the ground. The photos are not detailed enough to determine if the avalanches were separate crown, or connected by a fracture, with the second just an area of deeper release. Both avalanches were hard slabs, small relative to the path, and relatively harmless to people (HS-AS-R2D1-O/G).
The crown line shows the classic shape of cross loading. The skiers descended along the shallower edges of the wind pillow, and effectively outlined the initial slab. Hard slabs are commonly triggered from shallow locations, and then propagate into deeper areas. In the early season, sometimes the only areas that offer sufficient snow are cross loaded gullies.
"Bomber hard" snow can be attractive, because it keeps equipment off the underlying scree. Hard slabs, though, can propagate fractures along weak layers for long distances.
The secondary avalanche ripped to the ground. Tumbling over the underlying scree and rocks could be more hazardous than the avalanche. Rocks, stumps, and deadfall just under the snow are serious early season hazards.
The pair may have been complacent. It is easy to image a thought process like this: "It is early season, after all, and there was not much snow. The adjacent [lower angle and different aspect] slope was stable, so why should this little pocket be any different? The snow is super hard, which means it is strong. After all, it is a small slope if something goes wrong." I can imagine the thoughts, because I have rationalized similar poor slope choices.
This was a classic early season incident with a fortunate outcome. A combination of cross loaded hard slabs and complacent skiers lead to a good scare. It is a well-worn cliché, but bears repeating, "If there is enough snow to ride, there is enough snow to slide." Thinking about avalanche safety must begin with the first tour of the year. There was a similar incident in Canada on the 17th.