Avalanche Forecast

Issued: Dec 30th, 2014 8:30AM

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

triley, Avalanche Canada

Cariboos.

Special Public Avalanche Warning has been extended until January 4th for this region. Considerable avalanche danger is expected to continue due to the presence of a buried weak layer of surface hoar and/or a crust.

Summary

Confidence

Poor - Timing, track, or intensity of incoming weather system is uncertain on Friday

Weather Forecast

Mostly clear and cold overnight with moderate Northwest winds and alpine temperatures dropping to about -24. Clear with light Northwest winds on Wednesday with alpine temperatures rising up to about -16. Increasing cloud and a warming trend are expected for Thursday as the winds shift to the Southwest. Snow overnight and during the day on Friday combined with Northwest winds. Confidence is poor for intensity of the Friday storm, hopefully models will agree by tomorrow.

Avalanche Summary

Natural avalanches have been reported up to size 2.0 where the recent storm snow has been transported into a windslab; some of these avalanches have released or stepped down to the mid-December persistent weak layer of surface hoar and crust. Human triggering continues to be likely to very likely due to the storm slab sitting on a hard sliding surface with a weak layer of surface hoar at the interface.

Snowpack Summary

Extensive new windslab development over the last two days in the alpine, at treeline, and also in open areas below treeline as a result of strong Northerly winds. The new windslab may be easy to trigger, and may step down to the persistent weak layer of mid-December surface hoar. The touchy mid-December surface hoar layer is now buried below a 50-90 cm consolidated slab that developed during last weeks storm. Below 2100 m this slab sits on a thick, solid crust/ surface hoar combination and has been acting as a perfect sliding layer. A hard rain crust with facets from early November is buried more than 100 cm down and is currently unreactive, however; triggering from shallow rocky and unsupported terrain remains a concern.

Problems

Persistent Slabs

The persistent weak layer of buried surface hoar and crusts continues to allow for easy triggering with light additional loads on the snowpack. Remote triggering from adjacent terrain and long fracture propagations are expected to continue.

Stick to simple terrain, small features with limited consequence and be aware of what is above you at all times.>Avoid un-supported convex rolls in the upper below treeline and treeline elevation bands where the surface hoar may be well preserved and sitting on a hard crust.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 5

Wind Slabs

Strong winds have developed widespread windslabs in the alpine, at treeline, and also in open areas below treeline. The wind has consolidated the recent storm slab above the persistent weak layer allowing for easy or remote triggering.

Give cornices a wide berth when travelling on or below ridges.>Avoid freshly wind loaded features. Watch for reverse loading due to the Northerly winds.>

Aspects: North, North East, East, South East, South.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 3

Valid until: Dec 31st, 2014 2:00PM