Avalanche Forecast

Issued: Dec 22nd, 2012 8:11AM

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

danyelle magnan, Parks Canada

Glacier.

You may have noticed that the "persistent deep slab" is not a "problem" right now. While these layers still exist, the likelihood of triggering is low. Professionals are still tracking these layers, which may become a concern when conditions change.

Summary

Weather Forecast

Over the weekend we should see mostly overcast skies, light flurries (up to 5 cm today) and moderate southerly winds. Expect to see some transport of the new snow at ridgetop. A brief ridge of high pressure will bring back the sun on Monday and for Christmas day!

Snowpack Summary

SW winds overnight on Thursday formed thin windslabs on lee features above treeline. Recent storm snow has settled to ~40cm sitting on well settled snow. The Nov28 surface hoar is down about 80cm where it exists, and the early Nov crust is widespread and down about 1.5m. Tests on these layers indicate they would be hard to trigger.

Avalanche Summary

10-20 cm thick windslabs are reactive to human triggering on convex rolls and unsupported terrain at treeline and above. These avalanches were reported to be size 1's: 20-30m wide and 30m long. Overnight on Thursday, numerous size 2-3 natural slab avalanches were triggered by wind loading on steep N thru E aspects.

Confidence

Problems

Wind Slabs

Hard slabs exist right at ridgecrests, with soft slabs in the lees of ridges and ribs of terrain above treeline. These slabs are now shallowly buried and are most likely to be triggered on convex, unsupported terrain features.

Caution in lee and cross-loaded terrain near ridge crests.Be cautious as you transition into wind affected terrain.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Dec 23rd, 2012 8:00AM