Avalanche Forecast

Moderate - Timing, track, or intensity of incoming weather system is uncertain

A series of Pacific storms will continue to impact the region for the next few days. On Sunday overnight and Monday, 15-30cm of snowfall is expected throughout most of the region. Freezing levels are forecast to be around 1500m and alpine winds are expected to be strong from the SW. Another storm system is expected for Tuesday. Another 10-20cm is possible on Tuesday but freezing levels are forecast to climb as high as 2000m. Alpine winds should remain strong from the SW. On Wednesday, another storm pulse is expected with freezing levels dropping back to around 1500m.

On Saturday, explosives triggered a size 2.5 deep persistent slab avalanche in the Dogtooth. This was triggered in a steep, rocky, and unsupported terrain feature and released on the crust/facet interface on the ground. Other explosives resulted in thin wind slabs releasing. On Monday, storms slab will continue to build and are expected to become sensitive to human-triggering at all elevations, especially on steep, convex features. Natural avalanche activity is also expected to increase in frequency.

The new overnight snowfall will fall on top of around 25-50cm of recent storm snow. This storm slab sits over a variety of old surfaces including wind-stripped north aspects, hard wind slabs, facets, sun crusts and/or large-sized surface hoar. Of most immediate concern is a crust/surface hoar interface that is highly reactive. Reports suggest that the surface hoar exists as high as 2000m and is largest below 1700m. Strong SW winds are creating thick wind slabs in leeward features at alpine and treeline elevations. Deeper in the snowpack, surface hoar interfaces that were key players in November have been dormant but still may wake up with heavy loading or smaller avalanches stepping down. On very high northern aspects, a crust/facet interface may be found near the ground.