Avalanche Forecast

Tuesday night: Cloudy with flurries bringing 10-20 cm of new snow. Strong southwest or west winds, approaching extreme at ridgetop.

Wednesday: Cloudy with isolated flurries and a trace of new snow, continuing overnight. Moderate to strong west winds. Alpine high temperatures around -4, freezing level 1500 m.

Thursday: Mainly cloudy with isolated flurries and a trace of new snow, continuing overnight. Moderate west or southwest winds. Alpine high temperatures around -9, freezing level valley bottom.

Friday: Cloudy with continuing scattered flurries bringing a trace to 5cm of new snow, with light rain below about 1700 metres. Moderate to strong southwest winds, approaching extreme at ridgetop. Alpine high temperatures around -1 with freezing levels rising to 2000 metres.

It's now been a week since a widespread cycle of very large deep persistent slab avalanches occurred in response to the storms prior to Christmas, and four days since this avalanche was reported. The chance of full depth avalanches has diminished, but they could still occur under one of the following scenarios: we get unusually high accumulations of new snow or wind-blown snow; or from human-triggering in a thin, rocky start zone.

Thin wind slabs, which still could be nasty in steep exposed terrain, or if there is a terrain trap like a cliff, should be expected with the forecast incoming weather.

New snow and wind are forming fresh wind slabs in exposed locations. A reasonably consolidated upper snowpack, much of which was laid down during 50-100 cm of snow that fell just before Christmas, overlies a weak base. The bottom 30-50 cm of the snowpack consists of weak facets and crusts. Large deep persistent slab avalanches were noted during and immediately after the pre-Christmas storm and could be re-awakened by subsequent snowfall events.

• Fresh wind slabs will likely form throughout the day, diligently watch for changing conditions.
• Wind slabs are most reactive during their formation.
• Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
• Be aware of the potential for large avalanches due to the presence of a deep persistent slab.