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You can trigger avalanches involving 1.5-2.5 foot thick slabs in many locations. Conditions are most dangerous where older snow rests underneath the storm snow from this weekend (all upper elevation slopes and most middle elevation slopes that face away from the sun). Slides may break wider and further above you on the slope than you expect and can be triggered from long distances away. 

The likelihood of both human-triggered and natural avalanches will increase overnight as a storm impacts the area.

Fall weather produced a thin snowpack with a prominent weak layer at the surface (example photo). This layer was buried and then tested for the first time during the storm this past weekend. The results were unambiguous (Copper video, Titus video, Avalanche Database). Avalanches were easily triggered and many large, natural avalanches were observed. Avalanche activity was most intense in areas that received the most snow, our northern and western mountains. Here, natural avalanches broke hundreds and hundreds of feet wide and produced debris piles that would be plenty large to bury a person. Most of the observed slides failed in wind-loaded locations, but extensive cracking and collapsing and a few observed slides in sheltered terrain indicate that the weak snow that produced this problem exists there as well. You are most likely to run into problems in sheltered terrain in these areas that picked up the most recent snow.

Dealing with persistent slabs is part of the game here in central Idaho, but that doesn't mean it is easy. In fact, it is quite challenging. All of our skill sets picked up some rust over the summer (mine included), and we'll need to take the time to polish them. If you venture out to play in the snow today, prepare yourself to deal with wintertime snow hazards. Depending on where you start your day, you may or not encounter these immediately. Lower elevation slopes and middle elevation slopes that face the sun were snow free prior to this weekend's storm. In these areas where the snow fell on dry ground, the likelihood of encountering avalanche problems is far lower. Climbing upwards, that will change. As you move from areas without older snow to areas with older snow, your likelihood of triggering avalanches will increase significantly. It may not be immediately apparent visually if there is older snow on the slope you are thinking about skiing or riding. Fear not, it isn't far down and you should be able to detect it with your boots, hands, or ski poles. If you are finding it, I encourage you to travel conservatively. 

Uncertainty is high at this time of year. The data and observations available to us are limited and there is a lot of variation from location to location. We can expand our margins for safety to address this uncertainty. I've been enjoying the process of re-honing my backcountry travel skills and snowpack observation skills with a conservative mindset. Triggering avalanches 3 days in a row and watching them snap limbs off trees made this an easy choice. I've looked down a lot of steep slopes in the past week, spent a minute or two fantasizing about sliding down them, and then stuck to my conservative travel plans. It isn't always glamourous, but its the best way to guarantee that we will be in one piece when conditions line up for playing in steep avalanche terrain.