Archived

Avalanche Forecast

Dec 22nd, 2012–Dec 23rd, 2012

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: 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.

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

Avalanche 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