Avalanche Forecast

Issued: Dec 16th, 2012 9:04AM

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

pgoddard, Avalanche Canada

Sea To Sky.

Summary

Confidence

Fair - Timing, track, or intensity of incoming weather is uncertain for the entire period

Weather Forecast

Sunday night: Strong SE winds. Freezing level at surface. 10-15 cm snow.Monday: Strong winds changing from SE to W. Alpine temp lowering to -10. A few cm snow.Tuesday: Light to moderate SE winds. Alpine temp -7. Very light snow. Wednesday: Light SE winds. Alpine temp -11. 20 cm snow.

Avalanche Summary

Recent activity has been limited to a few small (size 1) soft slab avalanches in immediate lee features and small loose snow avalanches in steep terrain. Observations from early last week included several old size 2-3 avalanches, primarily from northerly aspects in the alpine. These events may have released on a weak layer of surface hoar, now down over a metre deep.

Snowpack Summary

Up to 50 cm of new snow may have buried a thin layer of surface hoar in some areas. Recent winds have been stiffening the low density storm snow and forming reactive slabs in exposed lee terrain. Below the recent storm snow weaknesses, the snowpack is well settled and strong. A layer of surface hoar that formed during late November has been found intact or decomposing in some locations down a metre or more. The early November crust/facet combination near the base of the snowpack seems to be dormant, at least in deep snowpack areas where it is buried too deeply by a stiff snowpack to be affected by light triggers on the snow surface.

Problems

Wind Slabs

Deep and touchy wind slabs exist on many slopes due to changing winds. Be alert for these below ridge crests, behind terrain features, and in cross-loaded gullies.

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Very Likely

Expected Size

2 - 6

Loose Dry

In areas protected from the wind, fast-moving sluff could knock you off your feet or carry you into a terrain trap.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Stick to non-avalanche terrain or small features with limited consequence.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Very Likely

Expected Size

1 - 4

Valid until: Dec 17th, 2012 2:00PM