Avalanche Forecast

Issued: Dec 12th, 2015 4:00PM

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

conrad janzen, Parks Canada

Banff Yoho Kootenay.

The great skiing continues...but make sure you stop, dig down and test for the Dec 3 surface hoar layer that is present below 2000m in many locations. This is particularly relevant in areas near the divide with a deeper snowpack.

Summary

Weather Forecast

We expect to see a few cm's of snow and increasing SW winds on Saturday night and into Sunday. Temperatures will be slightly warmer ranging from -2 to -10'C.

Snowpack Summary

In sheltered terrain below 2000m, a 30-40 cm soft slab sits over the December 3rd surface hoar. This layer continues to produce whumphs and easy shears in many locations, especially in areas to the West with more snow. No other significant shears have been observed. In the alpine isolated wind slabs exist in immediate lee areas.

Avalanche Summary

No new avalanches observed today in our forecast area. Ski cutting produced some small slabs on the Dec 3 SH in steep terrain below tree line near Bow Summit. Kananaskis Country reported one size 2.5 natural avalanche out of steep wind loaded alpine terrain in the Hero's Knob area.

Confidence

Due to the number of field observations

Problems

Persistent Slabs

A 30-40cm soft slab sits over the Dec 3 surface hoar in many sheltered locations below 2000m. Continue to 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: North, North East, East, South East, South, South West.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Wind Slabs

With increasing winds Saturday night, continue to watch for wind slabs in typically suspicious areas: 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.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Valid until: Dec 13th, 2015 4:00PM