Avalanche Forecast

Issued: Dec 1st, 2014 8:37AM

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

jlammers, Avalanche Canada

South Columbia.

Large and destructive human-triggered avalanches are still possible. Remain suspicious of steep, unsupported slopes at treeline and in the alpine.

Summary

Confidence

Fair - Due to the number of field observations

Weather Forecast

Very light flurries and a mix of sun and cloud are expected for the forecast period as a ridge of pressure remains parked over the province. Alpine winds will be moderate to strong from the northwest on Tuesday. On Wednesday and Thursday the winds should be generally light from the southwest. Alpine temperatures should hover at about -12 on Tuesday, rising slightly for Wednesday and Thursday. No significant snowfall is expected until Friday.

Avalanche Summary

Avalanche observations have been extremely limited, although explosives testing produced a couple of size 1.5 slab avalanches in the north of the region. These avalanches occurred at about 2000m and failed on one of the November persistent weaknesses. Avalanche activity on these deep layers is expected to become less frequent, although the potential consequences of a release continue to be severe.

Snowpack Summary

Recent strong and variable winds may have redistributed surface snow creating new wind slabs in exposed high elevation terrain. Recent rain and cooling have created a near-surface crust that extends to about 1900m. Approximately 100cm below the surface you'll likely find weak crystals which formed throughout early and mid-November. These weak crystals include facets on a hard rain crust, and surface hoar (which may also sit on a crust on steep southerly slopes). Snowpack tests on Sunday in Rogers Pass suggest the layers can still be human triggered, and if triggered, are capable of producing wide propagations and large avalanches.

Problems

Persistent Slabs

Up to 100cm of recent storm snow overlies weak crystals which are most reactive at higher elevations. Triggering may have become less likely; however, avalanches on this layer could be large and destructive.

Caution around convexities or areas with a thin or variable snowpack.>Conditions may have improved, but be mindful that deep instabilities are still present.>Be aware of the potential for large, deep avalanches due to the presence of buried weak layers.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 5

Valid until: Dec 2nd, 2014 2:00PM