Avalanche Forecast

Moderate - Wind effect is extremely variable

A mix of sun and cloud is expected on Tuesday with light alpine wind from the north and treeline temperatures around -8C. A mix of sun and cloud is also forecast for Wednesday and Thursday. Alpine wind is expected to remain light from the north and treeline temperatures are forecast to be around -12C.

An early report from Monday includes a report of a skier triggering a size 2 wind slab in the Dogtooth on a southeast aspect at 2400 m. Buried surface hoar beneath the 40 cm thick wind slab is expected to have increased the reactivity of the avalanche. On Sunday, natural sluffing up to size 2 was reported on steep sun exposed slopes. A skier triggered size 2 cross loaded wind slab avalanche was reported in the Dogtooth on a northeast aspect at 2300 m elevation. This avalanche stepped down to the mid-December weak layer. Explosive use in the Bugaboos area over the weekend resulted in numerous storm slab and wind slab avalanches with typical thickness of 30-60 cm. Most of these results were in the high alpine on various aspects. A couple of these avalanches stepped down to deeper layers or the ground. On Tuesday, lingering wind slabs are expected to remain a concern, especially where the slabs sit over a preserved layer of surface hoar. Wind slabs should be expected in steep, unsupported or convex leeward terrain features. In some places, moderate outflow winds may have caused reverse loading and formed thin new wind slabs in recent days.

25-50 cm of recent snow typically overlies the variable mid-January interface which consists of wind affected surfaces in exposed terrain, surface hoar in sheltered areas, and/or widespread faceted old snow. The bond between the new snow and the old surface is generally gaining strength with colder temperatures that followed the storm but weaknesses are lingering, especially where surface hoar is preserved. Strong southwest winds during the storm and moderate southwest winds following the storm have redistributed the new snow and developed wind slabs in leeward terrain features. The mid-December facet/surface hoar persistent weak layer can be found buried 50-100 cm deep and is generally considered dormant. However, a few storm slab and wind slab avalanches have recently stepped down to this layer in isolated areas. This layer remains an isolated concern for shallow snowpack areas where the layer is closer to the snow surface. With the next storm or period of warming, this layer could wake up and create a more widespread problem.