Avalanche Forecast

Issued: Dec 8th, 2013 8:00AM

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

Summary

Confidence

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

Weather Forecast

The arctic ridge of high pressure will remain until Wednesday but is beginning to weaken. A series of weak frontal waves will move into northern BC and will be pushed into the southern interior by the arctic ridge. This will result in light, intermittent snowfall for the next few days. A major change in the weather is expected late Wednesday or Thursday when the arctic ridge breaks down and allows a low pressure system to enter southern BC with a westerly flow.Monday: Mostly cloudy, light snow flurries, treeline temperatures around -15C, moderate NW alpine windsTuesday: A mix of sun and cloud, light snow flurries, treeline temperatures around -10C, moderate NW alpine windsWednesday: Mostly cloudy, light snow flurries, treeline temperatures around -10C, winds switching to SW

Avalanche Summary

No recent avalanches have been reported but incoming field data is still very limited in this region. No natural avalanches have been reported in the North Columbia Monashees/Selkirks since Thursday.

Snowpack Summary

Snowpack depths are likely to be highly variable across the region, with elevation, and in wind-exposed areas. Low-elevation and wind-affected areas likely have a shallow faceted snowpack. While in higher elevation sheltered areas 30-50 cm of recent storm snow overlies a variety of old snow surfaces including surface hoar in sheltered areas and/or sun crust on steep south facing slopes. In many areas the storm snow has yet to settle into a sufficiently cohesive slab. However, when temperatures rise, and we get additional snow, expect this crust/surface hoar interface to become a more dangerous problem. Strong NE winds after the storm caused reverse loading and wind slab formation on SE through W aspects in wind exposed areas. Lower snowpack layers include a surface hoar layer roughly 60cm above the ground and an early season rain crust at the base of the snowpack. While these layers have recently become inactive, residual risk of large, destructive avalanches exists, especially in areas with a thinner snowpack. The October crust can be found in the alpine on north aspects and the early November surface hoar appears to be isolated and drainage specific.

Problems

Wind Slabs

An icon showing Wind Slabs
Northerly outflow winds have reverse-loaded and cross-loaded exposed slopes forming wind slabs below ridge crests and behind terrain features. Don't let wind slabs in unusual places catch you by surprise.
Avoid traveling in areas that have been reverse-loaded or cross-loaded by winds.>Avoid freshly wind loaded features.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Persistent Slabs

An icon showing Persistent Slabs
Managing these persistent slabs can be tricky; they are stubborn and direct evidence of unstable snow may be lacking, but they can produce very destructive avalanches. Treat large open slopes with suspicion until stability is confirmed.
Dig down to find and test weak layers before committing to a line.>Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.>Use extra caution around convexities or large unsupported slopes.>Use extra caution in areas with a thin or variable snowpack.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 4

Valid until: Dec 9th, 2013 2:00PM

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