Avalanche Forecast

Issued: Dec 13th, 2016 3:55PM

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.

matt.mueller, Alberta Parks

Kananaskis.

This cold snap/drought is making the snowpack more and more complex. Approach terrain with a critical eye and thoroughly inspect the snowpack as you travel.

Summary

Confidence

High -

Weather Forecast

Sunny with no precip. An alpine high of -13 with light west winds.

Avalanche Summary

A size 1.5 natural slab avalanche was noted on Mt Buller. N aspect, alpine start zone. It entrained most of the snowpack on its way down.

Snowpack Summary

Two words: Complex and Variable!! Below treeline the snowpack is shallow and weak. Treeline is where the whole thing gets interesting. The Nov 12th crust is down 60cm and is starting to break down with a fine layer of facets immediately above and below. On top of these new facets, there is a 15cm thick layer of facets that have been growing throughout the cold snap. This thick layer was known as the Nov 24th persistent layer-despite being 15cm thick. To make it more complex, the recent winds have now created a windslab that is on the surface (at treeline). Its thought that the Nov 24th layer will instantly step down to the crust surface if initiated.Now for the alpine...take the treeline story and add yet another windslab to the surface. Working surface down, that leaves us with a surface windslab, followed by a buried windslab, followed by the 15cm thick facet layer...then the Nov 12 crust. Better read that a few times...

Problems

Wind Slabs

These slabs are on the surface at treeline. In the alpine we are finding 2 separate slabs. 1 on the surface and 1 buried by 15-20cm.

Avoid steep, open slopes.Avoid freshly wind loaded features.Dig down to find and test weak layers before committing to a line.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Persistent Slabs

What was known as the Nov 24th is now lumped into the Nov 12th crust. The reason is we expect any avalanche to scrub down to the crust surface. Note today's avalanche observations as a preview of what is coming. Exposed areas at treeline are suspect.

Use caution on open slopes and convex rolls Evaluate unsupported slopes critically.