New snow from the past couple of days has added up enough to be concerned about storm slab avalanches. Above 4000 feet, there’s 20-30 cms of new loose snow sitting on a newly formed weak layer. To avoid trouble with the new weak layer, avoid steep (above 35 degrees), open slopes on all aspects above 5000 feet, especially slopes with terrain traps at the bottom, such as a wall of trees or creek bed.
Slow yet steady snowfall is accumulating over the 1/13 Lucky Fri. crust. The crust, down ~ 1 ft, is widespread over the forecast region but crust thickness is variable. Weaker faceted snow is present near the crust. Additional interfaces with inconsistent sensitivity exist above and below the Lucky Fri. crust. With these complexities, be attentive to slab cohesion and mindful of terrain choices.
We’ve seen some quick changes to the snowpack over the past week. Last Wednesday – Friday, rain fell on the snowpack creating loose-wet weaknesses near the surface. On Friday afternoon, we saw the temperature begin to drop and snow replaced the rain. Over the weekend and the early part of the week, snow started to add up. A couple inches everyday has changed the structure of the snowpack. All the rain that fell last week has pooled up on a melt-freeze crust about 20-30 cms down in the snowpack. At lower elevations, the crust is thick and supportable. At higher elevations the rain turned to snow earlier, so the rain crust isn’t quite as thick and supportable. Because of this, there’s more snow on top of the crust at higher elevations. There’s a noticeable change around 4,500’ which is about where the rain/snow line was last week.
Yesterday, Micah and I went north. We’ve been keeping close tabs on the Kootenay Zone in Canada, so we wanted to see if conditions in the northern part of our zone were resembling conditions that we’re seeing across the border. We visited Ruby Ridge near Canuck Pass. It was good to visit a more remote and less visited part of the forecast zone.
Overall, we found a colder and drier snowpack than places in the southern part of the forecast zone. The snowpack up north wasn’t as deep, and it had more characteristics of a Continental snowpack than the snowpack in the southern Selkirk/Cabinets. The overall structure of the snowpack up north was similar, but it was definitely colder and drier than the southern zone. Sometimes the differences in the snowpack are elevation driven or aspect driven, but today the biggest change is North to South in the zone. Long story short, if you travel into the backcountry in the Purcells or Northern Selkirks, expect different avalanche conditions. Today, the avalanche danger is applicable to both areas, but depending on what weather we see in the future, the differences in the snowpack could become more drastic.
