Regions
Banff Yoho Kootenay.
Watch for rising avalanche hazard on Friday with forecasted new storm snow.
Weather Forecast
Scattered flurries for Wednesday with seasonal temperatures. Significant snow beginning Thursday night through Friday with 10-20 cm forecasted. Winds expected to be westerly in the moderate range. The last few days there has been a temperature inversion with ridge top temperatures significantly warmer then the valley bottoms.
Snowpack Summary
Total snowpack depths across the region range from 100-140 cm, and are comprised of soft surface snow above a weak and facetted snowpack. In many areas at treeline and above, recent winds have created thin windslabs. Foot penetration is to ground in most places, again demonstrating the weakness of the snowpack. This situation will not change soon.
Avalanche Summary
The widespread natural avalanche activity that was reported two days ago has subsided. No natural avalanches have been reported in the past 24 hours, however human triggered avalanches are still possible in many locations.
Confidence
Intensity of incoming weather systems is uncertain on Friday
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.
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.