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Avalanche
2024-04-27 – Avalanche Incident What: skier caught in an avalanche, carried 75-100 yards. Skier was not buried, no injuries, and skied out on own power. Objective: Two skiers planned a traverse from Sweeney Peak’s trailhead, up to Lolo Peak, to exit Mill Creek trail. Considerations taken in planning: - Weather: forecast from Thursday through Saturday was snow, 4-8”, along with relatively warm weather with lows of 30, highs of 33. - With the warm temperatures and expectation of additional snow, the route chosen was as conservative as possible with relation to slope aspect. - While there was no avalanche report issued, expectation for the skiers, as discussed in trip planning, would be that the report would have indicated considerable wet slab/wet lose danger on all aspects (possibly excluding high elevation) as the main concern. Flags: - No roller balls were observed during the entire trip. - Weather was warm, likely higher than forecast expectations. - Snow: recent snow of about 3-4” sat on a stout crust, which had been baked by the previous week’s warm weather. All of our observations indicated that the new snow seemed well bonded. - No cracking, no whumpfing. - Wind: light, variable. Under 5mph, no gusts. - Avalanches: On our first ski off Sweeney Peak’s ridge into the bowl, we skied a north 40-degree aspect. At 8,400 feet, Skier 1 triggered a small wet slab avalanche which ran 200-300 yards. Skier 1 was employing sluff management techniques by not skiing directly down a continuous line, and avoided being caught. Skier 2 skied the avalanche path with no incident. Incident: - Off of Lolo Peak, we skied along the eastern ridge, then down off the ridge along the least steep slopes, making our way to the northern ridge overlooking the upper basin above Carlton Lake at about 8,600”. - Both skiers met above this bowl – the route we intended to ski followed the northern ridge, eventually turning at the bottom to run down to the lake – this path included no terrain above 30 degrees in angle. - Upon reaching the bowl, we looked at the bowl and agreed to ski directly down it to the lake. The bowl is an east-northeast aspect, with a slope angle of roughly 35 degrees. No other discussion took place. - Skier 1 skied down the bowl, triggered a small wet slab avalanche, and Skier 2 yelled at him, and Skier 1 was able to ski out of the path. - Skier 2 briefly considered skiing the lower angle ridge above the bowl, but decided that skiing the avalanche path was acceptable. Perhaps 1-2 minutes elapsed before Skier 2 skied the slope. - At the base of the bowl, roughly 8,300-8,200 feet, skier 2 was knocked off his feet by a wet slab avalanche coming from behind, and carried about 100 yards. The avalanche was about 20 yards across. Skier 2 was not buried, and skied out of the avalanche. No trees, rocks, or cliffs were in the avalanche path. - The avalanche was made up of the new snow (3-4”), which had run on the old snow crust. - It is still not entirely clear where the snow which knocked Skier 2 down came from, perhaps it was remotely triggered from above as Skier 2 skied the avalanche path. Take Aways: - I am absolutely furious with myself for how we handled the day. Both incidents were entirely preventable, and could have easily been avoided by better decision making. o Still dealing with a lot of shame and embarrassment about the incident, particularly in writing this report and realizing the obvious mistakes. - Both incidents were directly caused by being on a slope and aspect which was not part of the plan or intended route. The discussion leading up to the day was to take as conservative of a route as possible. It was understood by both skiers that the purpose of the day was not to ski steep, avalanche prone slopes, but to pursue a big engaging traverse. - I am convinced that had we followed our actual route, neither incident would have occurred. - The first close call incident was a result of us deciding that we did not want to continue packing our way along the ridge, and once we saw a line that could be skied, we decided to do that with little discussion related to the fact that we were deviating from our intended route, the snow conditions to expect, or the alternatives. - The actual avalanche was also a result of poor communication, and failing to take the time to discuss our options and what we had seen to that point. Had we taken some time to slow down and discuss it more detail, we would (I hope) have concluded that the slope angle and aspect was VERY similar to the close call earlier, and should be avoided. - Familiarity – both skiers have skied the avalanched slope several times in the past, so I am sure some bias to that has to be added into the analysis. - Partially by design of the route, both incidents occurred on smaller slopes with very little consequence. There were very few trees, no cliffs, etc.