Avalanche Forecast

High -

Wednesday night: Cloudy with isolated flurries and a trace of new snow. Moderate west winds. Alpine low temperatures around -5, freezing level dropping to 1000 m.

Thursday: Mainly cloudy with isolated flurries. Moderate west to northwest winds. Alpine high temperatures around -10, freezing level valley bottom.

Friday: Cloudy with scattered flurries. Moderate to strong southwest winds, approaching extreme at ridgetop. Alpine high temperatures around +1 C, freezing levels rising to 2200 metres.

Saturday: Flurries accumulating 5-10 cm, with light rain below 1700 m turning to snow in the pm. Moderate west to southwest winds. Alpine temperatures dropping to -5 C by noon, freezing levels dropping to valley bottom.

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 wind.

A bit of new snow and moderate winds have formed 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.

• Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
• 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.