Avalanche Forecast

Issued: Dec 11th, 2015 4:17PM

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

conrad janzen, Parks Canada

Banff Yoho Kootenay.

The skiing is excellent but make sure you stop and put your snow profile skills to work. The Dec 3 surface hoar layer is widespread below 1900m. Dig down, look for this layer, and test it - it may become a tricky persistent slab avalanche problem.

Summary

Weather Forecast

Saturday will be overcast with a few flurries but little in the way of accumulations. Temperatures will range from -4 to -10 and winds will be light to moderate from the west.

Snowpack Summary

In most places below 1900m, a 30-40 cm soft slab of recent storm snow sits over the December 3rd surface hoar. This is producing easy shears in snow pit tests and slowly settling into a more cohesive slab, especially in areas to the West with more snow. In the alpine, winds from the recent storm have left wind slabs in lee areas.

Avalanche Summary

Avalanche control on Friday at the Lake Louise ski resort produced slab avalanches in alpine lee areas up to size 2. Small loose snow avalanches were also observed in steep alpine terrain.Â

Confidence

Due to the number of field observations

Problems

Storm Slabs

A 30-45cm slab is forming over a dangerous layer of surface hoar below 1900m. Treat all steep open slopes below treeline with suspicion until you can rule out this weak layer.

Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Wind Slabs

The recent storm was accompanied by moderate to strong winds at tree line and above. Things are improving but watch out for wind slabs in typically suspicious areas after a storm: leeward and cross loaded slopes or slopes near ridge crests.

Use caution in lee areas. Recent wind loading have created wind slabs.

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Valid until: Dec 12th, 2015 4:00PM