Continued low confidence in the overall snowpack structure is being felt by forecasters, despite recent benign weather and fewer natural and explosive-triggered avalanches of late. Increasing wind and warm temperatures on Thurs/Fri will likely contribute to worsening conditions.
Remain vigilant and settle in for a long winter of making conservative terrain choices to avoid negative interactions with avalanches.
The December 17 layer of persistent weak facets that formed during the prolonged deep freeze in early December is down 30-60 cm. This layer appears to be gaining strength, but is still worth considering. If a failure initiates on this layer, it may step down to the deep persistent layers resulting in larger avalanches.
The lower snowpack is comprised of very weak facets, with the mid and upper snowpack forming a slab over these facets at treeline and in the alpine. This weak basal layer is fairly uniform across most of the terrain and has shown the potential for human triggering, long propagations and remote triggering. Below treeline the midpack is weaker, forming less of a slab over the facets and a lower likelihood of triggering a slab avalanche as a result.
Forecasters from Mt. Norquay reported 2 size 3 deep persistent slabs on Mt Brewster that likely occurred on Tuesday afternoon. Lake Louise and Sunshine had limited results. The Visitor Safety field team did not observe any avalanches and experienced limited whumphing despite traveling through (low angle) rocky terrain.
10-20 cm of recent storm snow sits over a denser mid-pack which has formed a slab over the weak facet layers below. The December 17 persistent layer of surface hoar/facets is down 25-60 cm and becoming less reactive. The November 16 deep persistent layer of facets, depth hoar, and/or sun crusts is found near the base of the snowpack with test results continuing to show sudden failures. Puzzle Peak snow profile today.
On Wednesday, clear in the morning, with increasing clouds in the afternoon. No precipitation. Valley temperatures are about -4 and the ridge about -10. Wind increasing to moderate/strong from the SW into the afternoon.
