Regions
Banff Yoho Kootenay.
Increased hazard due to moderate W winds, continued light precipitation and mild temperatures is present especially in areas near the divide where more snow fall has occurred. Minimize exposure to wind loaded areas over the next few days. CJ
Weather Forecast
Continued moderate to strong West winds, light precipitation, and alpine temperatures between -5 and -10'C are forecast over the next three days with a cooling and clearing trend beginning on Wednesday.
Snowpack Summary
25cm of storm snow is present near the divide. Moderate to strong W winds and mild temperatures have formed wind slabs in open areas at tree line and above. The mid pack is facetted but still dense enough to support the weight of a skier in many areas. The October melt freeze crust or a mix of depth hoar and facets is present at the base.
Avalanche Summary
One size 2 natural avalanche slid over the "Heineken Hall" ice climb on Mt Dennis today reaching the bottom of the run out zone. Several size 1 moist sluffs were also observed in the Field area out of steep tree line terrain. One size 2 was observed yesterday on the "Sacre Bleu" ice climb on Mt Rundle. Wind appears to be the trigger in all cases.
Confidence
Intensity of incoming weather systems is uncertain
Problems
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.
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.