Avalanche Forecast

Moderate - Uncertainty is due to the fact that deep persistent slabs are particularly difficult to forecast.

The most recent weather model runs are showing very little precipitation through the end of the year aside from small dribs and drabs. Looks like the wind will begin to pick up out of the south/southwest on Thursday, especially in the higher alpine terrain features.

WEDNESDAY NIGHT: Freezing level at valley bottom, light northeast wind, no significant precipitation expected.

BOXING DAY: Clear skies, freezing level at valley bottom, calm/light wind up to at least 2000 m with potential for moderate west wind in the high alpine late in the day, no precipitation expected during the day, potential for a trace of snow Thursday night.

FRIDAY: Broken cloud cover, freezing level at valley bottom, calm/light wind at most elevations, moderate northwest wind in the alpine, trace of snow possible during the day.

SATURDAY: Scattered cloud cover, freezing level at valley bottom, calm/light wind at most elevations, potential for moderate northwest wind in the alpine, no precipitation expected.

Large destructive avalanche activity continued on Tuesday. A natural size 2.5 avalanche began on a north facing feature at 2200 m before ending up in a creek. Numerous size 3.5 avalanches were triggered by explosive control work in the central portion of the region on all aspects around 2500 m, crown depths were up to 200 cm.

On Monday control work produced very large (size 2.5 to 3.5) avalanches on a variety of aspects in the alpine. Some of these avalanches ran beyond historical norms and created new trim lines where there were once trees.

Avalanche activity was widespread Friday through Sunday with reports of natural, human and explosive triggered avalanches up to size 4.

The Purcells received 60-120 cm from last weekend's big storm which is settling into a deep persistent slab. There may be two layers of surface hoar buried between 70-180 cm below the surface.

The base of the snowpack is astonishingly weak, far more so than in the average season. The weak interface at the base is widespread across aspects and elevation bands meaning it's almost everywhere. It consists of crust, facets and depth hoar. This weakness has been responsible for some spectacularly large and destructive avalanches recently. 

• Conservative terrain selection is critical, choose only well supported, low consequence lines.
• Back off steep and aggressive lines, stick to simple terrain.