Avalanche Forecast

Issued: Jan 18th, 2015 8:26AM

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

esharp, Avalanche Canada

South Rockies.

Recent storms have been incrementally adding load to a layer of recently buried surface hoar. Check out the recent forecaster blog post for strategies on how to manage this scenario

Summary

Confidence

Fair - Wind effect is extremely variable

Weather Forecast

A weak ridge of high pressure will begin to build across southern British Columbia on Monday. Scattered flurries with light precipitation amounts are expected for the South Rockies. The ridge will strengthen Tuesday. The next system is forecast to hit the north Coast on Wednesday although the models are in disagreement about whether it will be able to displace the ridge and slide down into the southern interior. Temperatures will remain mild through the period with westerly winds becoming northwesterly.

Avalanche Summary

Human triggered avalanches can be expected in wind-loaded features at treeline where fresh slabs will be sitting on a layer of surface hoar.Â Recent snowpack tests suggest that if a deeper instability was triggered it would produce a large destructive avalanche.

Snowpack Summary

Fresh wind slabs are forming in lee features at alpine and treeline. The weekend storms hid a layer of surface hoar and/or a crust that exists in many places up to 1900m. At higher elevations the new slow fell on widely wind affected surfaces. The midpack is broken by a thick crust down 40-80cm that was buried in mid-December. In many places this crust is overlaid by facets and/or surface hoar. In areas where the overlying slab is thick and cohesive, large avalanches are possible on this interface. Closer to the ground a crust/facet interface that formed in November seems to be dormant for the time being.

Problems

Wind Slabs

Fresh wind slabs are forming in lee features. At treeline pockets of wind slab maybe sitting on top of a layer of surface hoar.

Be cautious as you transition into wind affected terrain.>Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

A buried persistent weakness, down 40-80 cm, should remain on your radar as it has the potential to produce large avalanches.

Dig down to find and test weak layers before committing to a line.>Avoid convexities or areas with a thin or variable snowpack where triggering could be more likely.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 5

Valid until: Jan 19th, 2015 2:00PM