Regions
Banff Yoho Kootenay.
Cooler temperatures are slowly helping to heal the snowpack. Watch for weak snowpack areas where the basal layer could be triggered, and isolated windslabs on high alpine features. Ski quality overall is poor to horrific. SH
Weather Forecast
Alpine temperatures will be in the -10 to -12C range for Thursday with light to moderate NW winds . The only "snow" in the forecast is the possibility of a few cm Saturday, but this will not affect the avalanche danger.
Snowpack Summary
Very strong westerly winds have seriously blasted the region. Wind pressed snow in lee terrain can be expected at treeline and above. A crust up to 2500m (higher on solar aspects) can be found in all areas. A field trip to Lake Ohara and a snow study flight E of the divide found moderate compression results on the basal depth hoar at treeline.
Avalanche Summary
The snow study flight East of the divide saw lots of previous activity up to size 3, with no new avalanches. The field trip to Lake Ohara saw only small wet slabs at treeline and below from last weekends cycle. The big alpine peaks had no visible activity with good visibility.
Confidence
Due to the number of field observations on Wednesday
Problems
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.