Wind slabs are a major concern right now. Be extra cautious in areas affected by the wind.
Confidence
Moderate - Freezing levels are uncertain
Weather Forecast
Partly cloudy with sunny periods through the forecast period as the South Rockies comes under the effects of a high pressure ridge centered over the interior of BC. Light flurries possible, but no significant precipitation in the forecast for the next three or four days. Freezing levels will be at valley bottom overnight and may rise to 1500 metres Monday afternoon, dropping to 1000 metres Tuesday night, then rising to 1500 metres Tuesday.
Avalanche Summary
East of the divide, there have been reports of skier controlled and natural avalanches up to size 2 in the recent storm snow. Naturals up to size 2 also reported on the East Slope. Reports from the western part of the region tell of numerous large natural avalanches as well as a size 1, loose-wet avalanche below tree line that failed on a rain/temperature crust down 20 cm. Operators have reported impressive results with explosives, up to size 3. South West winds continue to transport the snow at tree line and above into touchy wind slabs.
Snowpack Summary
Recent storms with strong southwest winds have redistributed the snow at tree line and above. Wind slabs have formed lee on slopes, and A crust that formed in early December has reappeared with recent loading, east of Crowsnest Pass. In general the new snow overlies scoured surfaces or hard stubborn wind slabs from last week. The mid and lower snowpack are getting stronger and settling well in these areas. West of the divide there's a mix of weak crystals around 30 to 50cm below the surface. This layer is a combination of surface hoar, facets and a hard crust that formed on steep solar aspects. Additional snow load will add to the size and reactivity of the developing persistent slab. About 60 to 80cm below the surface there is surface hoar layer which formed in December. Although no avalanches have been reported on this layer, it continues to produce sudden planar results in snowpack tests and could come into play with a large trigger such as a cornice, or simply additional storm loading. All areas have received extensive wind activity around tree line and above.
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.
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.