Backcountry Advisory 

As of Wednesday, Feb. 20

Four day’s of brilliant spring-like weather last week left us with a sun crust that varies dramatically in strength and thickness depending on aspect and elevation. The resulting warm snowpack temperatures had a variety of different impacts on the ensuing snow stability. A size 2.5 natural avalanche occurred on the south side of Whistler Mountain above Cheakamus Lake. This avalanche ran during the height of the warm spell with a crown line of up to 120cm in depth, the bed surface being the January crust.

This persistent deep-slab weakness that has been mentioned in previous reports has tightened in considerably after the temperatures fell last Friday night. There now appears to be a reasonably strong bridge over this layer in most areas within our region.

At higher elevations in the alpine, the sharp drop in snowpack temperatures last weekend created a very strong temperature gradient within the upper layers of the snowpack. In addition to the resulting surface faceting that occurred, depth hoar crystals of up to 4mm in size have formed in shallow rocky areas.

The storm cycle that swept through our region on Monday and Tuesday left us with 30cm of snow that was hammered by the strong winds in the alpine and at tree line. Natural slab avalanche activity and cornice fall was observed to have occurred during the storm. The storm-snow layers have since tightened-in dramatically, however, the bond between the storm snow layers and the old-snow surfaces should be considered suspect at best.

Conditions may vary and can change rapidly. Don’t assume that a slope that you skied earlier in the day is still a safe bet after the sun has been on it for several hours.

The avalanche danger in the areas adjoining the Whistler/ Blackcomb ski area boundaries is currently rated as Moderate .

For daily updates on the avalanche danger in these areas call 604-938-7676. For other areas in our region and further abroad try www.avalanche.ca or call 1-800-667-1105.

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