Avalanche Forecast

Issued: Dec 22nd, 2013 8:00AM

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

catherine brown, Parks Canada

Glacier.

Be cautious of sluffing in steep terrain.

Summary

Weather Forecast

Isolated flurries will continue today with freezing level at valley bottom and light to moderate ridgetop winds., with The incoming storm will deposit the bulk of the snow tonight into Monday, with freezing levels rising to 1100m. Forecast amounts are 10 to 20 cm. Temperatures will cool off and snow precipitation is forecast for Tuesday.

Snowpack Summary

15 of low density HST from the last two days sits on the surface. Below that up to 80cm of snow has settled over surface hoar at lower elevations, mixed forms and variable wind slabs at higher elevations. This interface is failing sudden planar in snowpack tests. At the base of the snowpack 2 persistent weak layers are surrounded by mixed forms.

Avalanche Summary

We observed 6 natural avalanches yesterday morning along the highway corridor, running in the storm snow with low density HN and moderate winds. The avalanches were mostly size 2-2.5, and deposited snow at the beginning of the runnouts.

Confidence

Intensity of incoming weather systems is uncertain on Monday

Problems

Persistent Slabs

A weak layer is buried down 60 to 90 cm. If triggered, a large high consequence avalanche will result. Carefully evaluate big terrain features by digging and testing adjacent, safe slopes.

Choose well supported terrain without convexities.Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 4

Wind Slabs

Firm, wind deposited snow has formed slabs in exposed terrain. These slabs are now covered by 15 cm of new snow. Use caution in lee areas at treeline and above.

Use ridges or ribs to avoid pockets of wind loaded snow.Be cautious as you transition into wind affected terrain.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3

Valid until: Dec 23rd, 2013 8:00AM