Use caution venturing into new terrain, especially in wind affected areas.
Confidence
Moderate - Due to the number and quality of field observations
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 rising above 1000 metres during the day.
Avalanche Summary
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. Operators are reporting 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. Operators have reported moist-wet snow below 1600 metres. East of Crowsnest Pass, new snow overlies scoured surfaces or hard stubborn wind slabs from last week. In general, the mid and lower snowpack are strong and well-settled 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 a developing persistent slab. About 60 to 80cm below the surface you may also find a 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.
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.