Regions
Banff Yoho Kootenay.
Avalanche Control is planned for the Sunshine Road tomorrow. No skiing or climbing on Bourgeau or the Eagles. JBW
Weather Forecast
Another storm tonite will bring possibly 5-10 cm followed by cold temperatures with a brief arctic air outbreak. Another storm will moderate temperatures by the weekend.
Snowpack Summary
Approximately 25 cm storm snow with strong south-westerlies over the last two days has created touchy wind slabs in all open areas above treeline. Windward slopes are scoured. bare. The mid pack remains strong enough to support most places where the snowpack is deeper than 60cm. The base is weak DH. Isolated SH at treeline beneath storm snow.
Avalanche Summary
A fresh size 2.5 was observed above Bourgeau Right Hand Waterfall that ran down to the edge of the cliffs. The crown was blown in beneath the cornice but suspect storm snow snow slab with wind loading as the trigger.
Confidence
Forecast snowfall amounts are 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.