Three different things to consider: at low elevations loose wet avalanches, often running on a crust; lingering dry storm slabs on shady slopes at high elevations; and on southerly aspects at higher elevations is the worst of the bunch -- dry snow sitting on a crust.
The recent snow hasn't yet bonded to the lingering interfaces from late March and early April. This snow is being triggered and propagating widelyAvalanches triggered on these deeper layers could be large and destructive.
Surface snow will destabilize and may avalanche naturally with daytime warming and especially solar exposure.
A weak layer of facets exists near the base of the snowpack. The likelihood of human triggering is low given the layer's depth.
Suspect terrain includes steep, shallow, and rocky terrain where the snowpack varies beween thin and thick.
A serious avalanche incident occurred in the backcountry just east of Revelstoke on Wednesday. Details are available here. This is representative of the recent storm snow above a crust problem.
Otherwise, reports from Monday and Tuesday included many more storm slab and wind slab avalanches, several that were noted for being triggered remotely (from a distance) and a significant number of avalanches attributed to the problematic late-March and early April failure planes discussed in our snowpack summary, now buried under the full depth of recent snowfall. The presence of surface hoar and facets in particular has been noted in some of the more prominent reports of touchy conditions from the past few days.
Looking forward, the need for backcountry travelers to manage a wide range of avalanche concerns that vary by elevation and aspect continues.
Recent storm snow totals at higher elevations (where it is wintery and the snow is dry) are around 30-60 cm, with up to 100 cm reported at high elevations on the west side of the Purcells (e.g. near the Bugaboo group). And of course it's deeper on lee features
All this snow overlies either a widespread melt-freeze crust buried April 7, a weak interface of faceted snow and surface hoar buried at the end of March, or some combination of the two. As the recent snow strengthens, both of these interfaces can serve as weak layers; numerous recent avalanches, some with wide propagation, are attributed to each.
The mid-snowpack is strong. However, November depth hoar is still prominent at the base of the snowpack. This layer remains a concern in rocky, shallow, variable depth snowpack areas at treeline and above.
Thursday Night
Mix of cloud and clear periods. Light west or southwest winds. Treeline temperatures around -8 with freezing levels to valley bottom.
Friday
Sunny with cloudy periods. Dry. Light west winds. Treeline high temperatures around 0 C with freezing levels to around 1600 m.
Saturday
Increasing cloud with isolated flurries. Light to moderate south winds increasing over the day and evening. Treeline high temperatures around +2 C with freezing levels to 2000 m.
Sunday
Cloudy with trace to 5 cm of snow. South light winds and moderate gusts. Freezing level near 2000 m and treeline temperatures around zero.
More details can be found in the Mountain Weather Forecast.
