Avalanche Forecast

Issued: Dec 22nd, 2013 8:26AM

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

swerner, Avalanche Canada

South Columbia.

Summary

Confidence

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

Weather Forecast

The Pacific frontal system will push through the Interior regions Sunday through Monday. This will bring moderate snow amounts and strong SW winds. Overnight Sunday: Snow amounts 5-10 cm.Monday: Snow amounts 15-25 cm. Alpine temperatures near -5. Ridgetop winds moderate from the West. Freezing levels 800 m.Tuesday: Mainly cloudy with some flurries. Alpine temperatures near -14. Ridgetop winds moderate from the West gusting strong. Freezing levels back to valley bottom.Wednesday: Cloudy, and dry. Alpine temperatures near -8. Ridgetop winds light from the West.

Avalanche Summary

On Saturday, one skier triggered size 1 slab avalanche was triggered in the recent storm snow and failed on a persistent weak layer buried down 60 cm in the Southern part of the region. Other operators reported loose dry surface sluffing from steeper terrain features. With forecast new snow and wind you can expect the avalanche hazard to rise, and natural avalanche activity is likely.

Snowpack Summary

New snow (up to 40 cm in some places) has buried older wind slabs in exposed terrain at treeline and above. The new storm slab is touchy to rider triggers, and natural loose dry sluffing from steeper terrain exists. Average snowpack depths at treeline range from 100 cm -150 cm. Buried down 40-60 cm is a surface hoar, and facet layer. This layer has recently been reactive to riders and natural triggers and both cracking and whumpfing have been noted.Digging deeper down 70-90 cm, is the late-November interface, which consists of a sun crust/ facet combo on steep south facing slopes and larger, proud surface hoar crystals in sheltered areas at lower elevations. This layer is generally considered to be "stubborn" to trigger. However, professionals are keeping a close eye on this layer especially with forecast new load.At the base of the snowpack the October crust is most predominant on north-facing alpine slopes with smooth ground cover. Triggering this weakness is unlikely, but if triggered the resulting avalanche would be very large and consequential.

Problems

Storm Slabs

New storm snow may be touchy and reactive, especially in wind affected areas. Natural avalanche activity is expected. Further loading and smaller avalanches may trigger buried weak layers and initiate large- very large avalanches.

Whumpfing, shooting cracks and recent avalanches are all strong inicators of unstable snowpack.>Avoid avalanche terrain during periods of heavy loading from new snow, and wind.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 4

Persistent Slabs

Persistent weak layers of facets, surface hoar, and/or a crust exist in the upper 90 cm of the snowpack. With more load they may be susceptible to triggering, creating large - very large destructive avalanches.

Be aware of the potential for large, deep avalanches due to the presence of buried weak layers.>Dig down to find and test weak layers before committing to a line.>Choose conservative lines and stick to supportive, low angle terrain.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

3 - 5

Valid until: Dec 23rd, 2013 2:00PM