Avalanche Forecast

Issued: Jan 4th, 2015 8:13AM

The alpine rating is high, the treeline rating is high, and the below treeline rating is considerable. Known problems include Storm Slabs and Persistent Slabs.

Avalanche Canada triley, Avalanche Canada

The storm is moving across the interior regions tonight resulting in HIGH avalanche danger by morning. Heavy snowfall and strong winds are expected to develop new storm slabs.

Summary

Confidence

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

Weather Forecast

A moist Pacific storm is moving into the region from the Southwest on Sunday. Expect strong Southwest winds overnight and 10-20 cm of new snow by Monday morning. Winds should become moderate Northwest during the day Monday with periods of flurries or light snow. Winds becoming moderate Westerly Monday evening as the next pulse of moisture moves into the region bringing 10-20 cm by Tuesday morning and another 10-15 cm during the day. Warm air and strong Southwest winds are expected on Wednesday at the end of the storm. Freezing levels should be at valley bottoms until Wednesday afternoon when they are expected to rise to about 1300 metres.

Avalanche Summary

No new avalanches reported. Forecast new snow and wind is expected to develop a reactive new storm slab.

Snowpack Summary

Forecast new snow and wind is expected to develop a new storm slab. There is about 30-50 cm of recent storm snow combined with variable winds that have produced windslabs on all aspects in the alpine and at treeline. Pockets of warm air in the north have likely made the snow dense in some places, while predominately westerly winds have set up fresh wind slabs in exposed lee areas. The persistent mid-December crust/surface hoar layer appears prominent in the south of the region and is still reported to fail easily during snowpack tests. It is most prominent at within a few hundred metres of treeline elevation. On average it can be found around 60 cm below the surface, although it has variably been reported anywhere from 30-90 cm below the surface. In the north of the region, this layer is present, although reported to be harder to trigger. Further down, a hard rain crust with facets from early November is buried more than a metre down and is currently unreactive. However, triggering from shallow rocky and unsupported terrain remains a concern.

Problems

Storm Slabs

An icon showing Storm Slabs
Forecast heavy snow and strong winds are expected to develop a new storm slab that may release naturally or be very easy to trigger from light additional loads like a skier or rider.
Minimize exposure during periods of heavy loading from new snow, wind.>Avoid freshly wind loaded features.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 4

Persistent Slabs

An icon showing Persistent Slabs
The developing new storm slab may be enough load to increase the likelihood of triggering the mid-December weak layer.
Stick to small features with limited consequence and be aware of what is above you at all times.>Minimize exposure during periods of heavy loading from new snow, wind.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 5

Valid until: Jan 5th, 2015 2:00PM