4-8 inches of snow fell across the Selkirks and Cabinets zone last night. While out and about, be aware of the possibility of avalanches caused by this new snow. In addition to the ‘new snow’ red flag, the persistent weak layer is still lurking and could produce a 2-3 ft deep avalanche. With this in mind, try to avoid steep, filled in slopes near ridges.
The old snow interface in the bottom third of the snowpack is still a layer of concern. Test results showed more resistance to failure than a week ago. The layer still has the capability of failing and propagating across a slope. Steep, open slopes above treeline are the most likely places to trigger an avalanche on this layer.
(12/8/2022)
Data pit, Rpman Nose
Photo: J. Thompson
New snow and colder temperatures have created some good powder conditions in the backcountry! Be aware of new snow concerns such as wind loading, new slab formation, and loose snow avalanches. Keep your eyes out for other avalanche activity in the area.
(12/8/2022) Photo: J. Thompson
It’s snowing! Weather stations and ski areas around the zone are reporting 4-6’’ of snow last night. IPAC Forecasters will get out today to see how the new snow bonded to the old snow. Until then, be aware of an increased risk of avalanche due to the new snow. Look for signs of instability such as whoomphing or cracking. Winds looked to be moderate overnight, so I wouldn’t expect a lot of wind loading this morning, but once again, keep an eye out for fresh wind loading. Prevailing winds last night were out of the south, so any loading would probably be on NE-N-NW slopes.
Yesterday, we snowmobiled up the Ruby Creek Road out of Naples, into the Roman Nose area. On the way up at 5500 ft, we dug a snow pit and found 72 cm of snow. The majority of the snowpack was comprised of snow from the December 1st storm. The bottom 25 cm was made up of old sugary snow (basal facets). The propagation saw test yielded results of PSTP22, Q2 and PSTN21, Q3. The slab feels stiffer and is showing more resistance to failure than it did a week ago.
We skied up to a ridge at 6250 ft and dug another snow pit. This time the snow was 130 cm deep and the slab felt thicker and more supportive. It was so supportive, in fact, that our tests didn’t register any notable failures. While touring around, we noted that there was a lot less settling and whoomphing in the snowpack than a week ago. Thin spots in the snowpack, around trees and rocks were the places that we were able to trigger whoomphing and make the weak layer underneath fail. Be heads up for slopes that look bulged in the center. We noticed some slopes that looked like there could be some capping or bridging over the weak layers. During the early season, sometimes all it takes is finding that thin spot with your sled to trigger a slide.
