Regions
Banff Yoho Kootenay.
One more day of stable weather on Sunday. After this, we move into a trend of slowly increasing avalanche danger. SH
Weather Forecast
Saturday night should be the last bitter night of -30C. Sunday expect light winds and no snow. We are moving into a SW flow for the extended forecast period, bringing with it increased winds, warmer temperatures, and the possibility of 15-20cm by the middle of next week.
Snowpack Summary
5-10 cm of facetted snow sits on the spotty January 30th surface hoar. This is the layer to watch next week. In the alpine this snow sits over a firm wind slab or facetted sun crust on S & W aspects. Minor wind effect on shady alpine features. Deeper snowpack areas have good mid pack strength over the weaker basal depth hoar/crust.
Avalanche Summary
No new avalanches have been observed or reported.
Confidence
Due to the number and quality of field observations on Saturday
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.