Regions
Banff Yoho Kootenay.
Extensive wind effect can be found in open areas. We are slowly gaining confidence with the snowpack, but a cautious approach to terrain is important as large avalanches are still possible.
Weather Forecast
The arctic ridge starts to break down Friday over the area with increasing cloud but still cold conditions for Friday. Winds will increase to moderate/strong above 3000m but will stay light at valley bottom. Some light snow over the weekend with 5-10cm at treeline by Sunday evening and slightly warmer (but not warm!) temperatures.
Snowpack Summary
The upper pack consists of settling storm snow with extensive wind effect in open areas. This overlies the mid-pack where there are three weak layers that are gaining strength. These layers continue to produce moderate, sudden planar test results on surface hoar in deep tap tests, and hard to no results with standard compression tests.
Avalanche Summary
A couple of wind slabs in steep terrain were reported and were suspected to be in the last 24-36 hours, 1 triggering a deeper slab. No other reports of avalanches in the last 24 hours with good visibility.
Problems
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.