Avalanche Forecast

Issued: Dec 14th, 2015 8:38AM

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

esharp, Avalanche Canada

South Columbia.

The danger has come down, but large human triggered avalanches remain possible. Start with small test slopes and build up slowly to the bigger terrain features. There is still a lot of uncertainty associated with this early winter snowpack.

Summary

Confidence

Moderate

Weather Forecast

A northwest flow will bring light snowfall, and cool temps throughout the forecast period. TUESDAY: Flurries bring up to 2cm of snow, light northwest winds, -5 at 1500m. WEDNESDAY and THURSDAY: Overcast, light northwest winds.

Avalanche Summary

Avalanche activity appears to have tapered off since Friday. Reports from over the weekend describe sluffs in steep terrain, natural avalanches up to size 1.5 failing on a mid-storm instability, and skier and explosive controlled avalanches in steep or wind loaded features. No new avalanches were reported to have released on the layer of buried surface hoar over the weekend, although this may be because people have been avoiding locations where it likely to be found. Because the consequences of triggering this layer could be catastrophic I'm keeping it in mind for the time being.

Snowpack Summary

Between 80 to 130cm of snow fell last week in the South Columbias. You may find a thin crust about 15 to 40cm below the snow surface as high as 1800m. Below the new snow lies the early December persistent weak layer. This layer may be found as either an old sun crust on south facing features in the alpine, or as large grained surface hoar and small facets in isolated pockets bellow treeline, especially between 1400m and 1800m. Recent test results on this interface have been widely variable. Sudden planar, resistant planar and sudden collapse results have been reported from snow pit tests on the surface hoar as recently as December 13th. Recent winds out of the south have formed wind slabs on lee features that are mainly confined to the alpine, but you may find the odd fresh wind slab at tree-line too. The mid and lower portions of the snowpack are thought to be well settled.

Problems

Wind Slabs

The storm slab problem should be settling out quickly, but I would still be wary of steep unsupported features, slopes immediately lee of ridge crest and convexities.

Avoid lee and cross-loaded terrain near ridge crests.>Start with simple terrain and take a curious/experimental approach to the snowpack. You may be able to step out into challenging and even complex terrain after learning more about the snowpack.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Persistent Slabs

A layer of buried surface hoar can be found below tree-line between 1400m and 1800m. Test profiles suggest this interface varies widely in reactivity indicating that it may still be sensitive to human triggering.

Avoid open slopes, convex rolls, burns, cutblocks and terrain traps when traveling below treeline. This is where buried surface hoar is best preserved and most volatile.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible

Expected Size

2 - 4

Valid until: Dec 15th, 2015 2:00PM