Although the temperature is forecast to remain cool at upper elevations, when the sun does come out it can have an immediate impact on those slopes directly facing it.
Confidence
Moderate - Timing or intensity of solar radiation is uncertain
Weather Forecast
TUESDAY: Mix of sun, cloud and isolated flurries / Light west wind / Alpine temperature -5WEDNESDAY: Cloudy with isolated flurries / Light to moderate southwest wind / Alpine temperature -5 THURSDAY: Mainly cloudy with scattered flurries / Light to moderate southwest wind / Alpine temperature -3
Avalanche Summary
Through the weekend avalanche activity included several natural and explosives controlled storm and wind slab avalanches size 1.5-2.5. These occurred on all aspects from tree line into the alpine. 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.
Snowpack Summary
Last weeks storms totaled 100cm of snow accumulation in parts of the region. 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
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.