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Whistler/Blackcomb Backcountry Avalanche Hazard Advisory

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As of Wednesday, Jan. 15

The snowpack has been very busy despite mild temperatures and reasonably fair weather. The two weeks of heavy precipitation over the holidays gave way to a slight inversion and clear skies, followed by the present pattern of weak weather systems and small precipitation amounts.

The mild period allowed the storm snow to settle and gain strength, however, the settlement resulted in significant temperature gradient vapour transfer to the surface and the development of well-developed small facets near the surface. Around tree-line (or 1,800m) these facets are punctuated by a series of rain crusts.

The 6mm surface hoar layer that was buried on Dec. 25 is now buried 0.7-1meters and has been indicating moderate shear strength when tested. A natural cornice failure on Monday resulted a size 3, 0.8m deep, 1,000m wide slab avalanche on this surface hoar layer.

Finally, the current series of weak systems is leaving thin layers of loose snow and wind slab (depending on aspect and elevation) on the previously reported facets, crusts and decomposing and fragmented snow.

The avalanche hazard rating for the backcountry adjacent to the Whistler-Blackcomb ski areas on Wednesday, Jan. 15, 2003 is MODERATE. Be aware of cornices, as they are large enough triggers to get things moving deep in the snow, thin wind slabs above terrain traps, and any significant precipitation events (particularly if they involve significant warming).

Keep up to date through the Canadian Avalanche Association Bulletin at ww.avalanche.ca or 1-800-667-1105, or call 604-938-7676 for a local bulletin.

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