The sun packs a powerful punch at this time of year. Consider the avalanche danger to be one step higher around slopes that see direct sunshine on Sunday.
Confidence
Moderate - Timing or intensity of solar radiation is uncertain
Weather Forecast
Sunday: A mix of sun and cloud with light flurries in the evening. Light southwest winds. Alpine high temperatures of -8.Monday: Mainly cloudy with isolated flurries and a trace of new snow. Moderate southwest winds. Alpine high temperatures of -10.Tuesday: A mix of sun and cloud. Light southwest winds. Alpine high temperatures of -10.
Avalanche Summary
Storm snow has grown touchy cornices and formed widespread soft storm slabs near ridge tops and open areas at treeline and below. On Thursday and Friday, explosives control in the Fernie area produced loose dry and storm slab releases reaching from size 1.5 to 2.5 with some slabs reaching up to 80 cm in depth.On Wednesday there were reports of several natural and skier triggered size 1 loose, dry storm snow releases on all aspects above 1700 m, as well as a few size 2-2.5 natural storm slab releases on northeast aspects that where possibly cornice triggered.Tuesday a size 2.5 natural storm slab release that was likely triggered by a cornice collapse, was reported on a northerly aspect in the alpine. Cornice collapses up to size 1.5 were also reported but did not produce slab releases on the slopes below.
Snowpack Summary
50-60 cm of new low density snow accumulated in the region over Friday night. This brings snowfall totals from the past week to about 100 cm. This storm snow overlies various old surfaces including old hard wind slabs, crusts, facets and more isolated surface hoar. Also in the upper to mid snowpack, a surface hoar layer buried mid-February is now 80 to 100 cm below the surface on sheltered northerly aspects.Deeper in the snowpack, the widespread mid-December weak layer sits about 200 cm deep. This consists of a crust, facets or surface hoar.Near the base of the snowpack, a crust/facet layer could be awoken from a thin-spot trigger point, or with a very large load like a cornice fall.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.