Careful snowpack evaluation and conservative decision-making is essential right now as the lingering deep instability will be with us for the foreseeable future. Significant temperature change is expected in the next 24 hours.
Weather Forecast
Temperatures warming to reach a maximum of -5C in the Columbia Icefield area by midweek accompanied by light Southwesterly winds. Potential for significant snowfall by the end of the week, starting on Wednesday and increasing in intensity towards the weekend.
Snowpack Summary
Up to 30cm of low density storm snow is settling and overlies existing wind slabs which in places has a very weak faceted basal layer. Below tree line the snow pack has very little support except in isolated open areas where wind slabs may exist. New windslabs have formed at upper elevations but lots of snow is still available for transport.
Avalanche Summary
Road patrols in the South end of the forecast area observed numerous size 3 slabs that failed on the basal facets and widespread smaller avalanches to size 2 on all aspects in the alpine involving windslabs and loose dry avalanches. With recent storm snow plastered to steep terrain, natural loose dry activity is expected with warming temps.
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.
Loose Dry
Loose Dry avalanches are the release of dry unconsolidated snow and typically occur within layers of soft snow near the surface of the snowpack. These avalanches start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-dry avalanches include point-release avalanches or sluffs.