Cornice falls have been responsible for most of the avalanches reported in the past few days. Wind slabs or cornices may trigger persistent weak layers resulting in large avalanches.
Summary
Confidence
High -
Weather Forecast
Overnight: Cloud developing with moderate-strong southwest winds and freezing down to 1000 metres. Wednesday: Strong southwest winds combined with 3-5 cm of new snow and daytime freezing up to 1700 metres. Thursday: Overcast with moderate south winds and a couple of cm of new snow. Daytime freezing level to 1800 metres. Friday: Another 3-5 cm of new snow with sunny breaks in the afternoon and freezing levels around 2000 metres.
Avalanche Summary
Several natural cornice falls were reported on Monday up to size 3.0.
Snowpack Summary
Last week's stormy weather brought up to 40 cm of snow to upper elevations. This storm snow overlies a rain crust below about 2000 metres and a sun crust on solar aspects at higher elevations. Several other temperature and or solar crusts are likely to exist within the storm snow, mainly at lower elevations and on solar aspects. Moderate to strong southwest winds during and since the snowfall formed wind slabs on leeward slopes and promoted the growth of large, fragile cornices along ridgelines. At higher elevations, the February weak layers are down about 120-150 cm and the deep mid-December facet layer and November rain crust both still linger near the bottom of the snowpack. These layers were active during a storm in mid-March and produced some very large avalanches. Occasional deep releases were also reported in late March and these deeply buried weaknesses remain a serious concern as solar radiation and warming temperatures begin to penetrate the snowpack at increasingly higher elevations. Cornices and wind slabs are also weakened by these warming effects and have the potential to trigger deeply buried weak layers if they release.
triley,
Avalanche Canada
