Avalanche Forecast

Issued: Jan 10th, 2017 4:18PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs and Persistent Slabs.

Avalanche Canada rbuhler, Avalanche Canada

Watch for areas that have recently been affected by the wind. Wind slabs are expected to be lingering in leeward terrain features. Buried weak layers remain an isolated concern and avalanches have the potential to step down to a deeper layer.

Summary

Confidence

Moderate - Wind speed and direction is uncertain

Weather Forecast

Sunny conditions are expected on Wednesday with treeline temperatures around -15C in the afternoon and light northerly wind in the alpine. Sunny conditions continue for Thursday and Friday with treeline temperatures remaining around -15C during the afternoon and light to moderate alpine wind from the northwest.

Avalanche Summary

On Monday, ski cutting produced numerous size 1-1.5 storm slabs. These slabs were typically 15-20 cm thick and were reactive in the alpine and at treeline. One natural was also observed from a steep, unskiable terrain feature. On Wednesday, recently formed wind slabs may still be reactive to human triggering. With the winds recently switching directions, wind slabs should be expected on a variety of aspects. Persistent slab avalanches also remain an ongoing concern. Buried weak layers are creating a low probably, high consequence problem for the region. Extra caution is recommended in shallow snowpack areas of the region.

Snowpack Summary

15-20 cm of new snow has buried a variable old snow surface which consists of heavily wind scoured surfaces or old wind slabs in exposed terrain, surface hoar in sheltered terrain, and/or widespread faceted old snow. Recent moderate winds from a variety of directions is expected to have redistributed some of this new snow in wind exposed terrain. The mid pack appears to be variable throughout the region and the structure is dependant on snow depth. In deeper snowpack areas, the snowpack appears to be well settled and right side up with isolated concerns for the mid-December weak layer. In shallow snowpack areas and lower elevations, the snowpack is heavily faceted and there are concerns for the mid-December weak facet layer as well as old faceted crusts deeper in the snowpack and a weakness at the bottom of the snowpack. Due to inconsistencies in snowpack structure throughout the region, the snowpack needs to be treated with respect and further investigated at a local scale in your riding area.

Problems

Wind Slabs

An icon showing Wind Slabs
Recently formed wind slabs may still be reactive to human triggering in immediate leeward features in wind exposed terrain. Wind direction has changed recently and wind slabs may exist on all aspects.
Wind direction has changed recently. Watch for slabs on all aspects.Use ridges or ribs to avoid pockets of wind loaded snow.Avoid areas where the surface snow feels stiff or slabby.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

An icon showing Persistent Slabs
Where stiffer snow overlies weak, sugary snow, there is the potential to trigger large, destructive avalanches. Remember that a small wind slab avalanche may provide enough of a trigger to step down to this deeper weakness.
Be aware of the potential for full depth avalanches due to deeply buried weak layers.Danger exists where denser snow overlies weak, sugary snow below.Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Jan 11th, 2017 2:00PM