The upper snowpack is faceted creating a weak slab over a faint, inconsistent layer of surface hoar/facets on a crust down 40cm. The thicker snowpack spots have a strong mid-pack bridging the deep persistent basal weakness (depth hoar). Thinner snow-pack zones are much less consolidated, where the midpack may act as a slab on the basal depth hoar.
Avalanche Summary
Yesterdays field team reported dry loose from steep Alpine terrain and thin (5cm), but present soft wind effect at immediate ridge top; reactive to skis but not alarming or hazardous. 2600m near Cataract Pass in the Columbia Icefields region. No other reports of new avalanche activity.
Confidence
Wind effect is extremely variable
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.