Avalanche Forecast

Issued: Jan 2nd, 2015 7:53AM

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

Avalanche Canada jfloyer, Avalanche Canada

A crust/surface hoar layer from mid-December remains the primary concern and requires careful terrain selection. New snow may conceal wind slabs in exposed terrain.

Summary

Confidence

Fair - Intensity of incoming weather systems is uncertain on Monday

Weather Forecast

Saturday: mostly cloudy with flurries. Treeline temperatures around -12C and winds mostly light from the northwest. Sunday: Dry during the day with snow starting late in the afternoon. Treeline temperatures around -15C, winds light and variable. Monday: 10-20 cm new snow expected by the end of the day Monday. Freezing levels are expected to remain below valley bottom, with treeline temperatures around -10C. Winds anticipated to rise to around 40 km/h.

Avalanche Summary

Natural avalanches have been reported up to size 2 where the recent storm snow has been transported into a wind slab. Some of these avalanches have released on or stepped down to the mid-December persistent weak layer of surface hoar and crust.

Snowpack Summary

Uneven distribution of new snow amounts and temperatures within this region with the storm that ended on Friday have likely further enhanced snowpack variability in this region. 20-25 cm new snow fell in the north, 10-15 cm in the south. 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 elecation. 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

Persistent Slabs

An icon showing Persistent Slabs
Persistent slab problems have been of particular concern in the south of this region at elevations between 1600 m and 2100 m. The culprit is a crust with weak surface hoar crystals. This layer is found to the north as well, but is harder to trigger.
Avoid steep rollovers at and just below treeline where the surface hoar may be well preserved and sitting on a hard crust.>Stick to small features with limited consequence and be aware of what is above you at all times.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 5

Storm Slabs

An icon showing Storm Slabs
Recent new snow and winds have set up touchy wind slabs in exposed areas and storm slabs in more sheltered locations. These have sufficient mass to be a problem in themselves, or they could trigger deeper weak layers below.
The recent snow may now be hiding windslabs that were easily visible before the snow fell.>Choose conservative lines and watch for clues of instability.>Choose well supported terrain without convexities.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 4

Valid until: Jan 3rd, 2015 2:00PM

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