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Archived

Avalanche Forecast

Nov 26th, 2012–Nov 27th, 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
3: Considerable
The avalanche danger rating in the alpine will be considerable
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.

Many steep lines were skied over the weekend, which gives evidence that the snowpack is generally strong.  Remember that pockets of unstable snow exist in isolated locations.  Be aware when skiing near or over  terrain traps

Weather Forecast

An upper ridge of high pressure will dominate the weather today in the Columbia's.  Dry conditions are expected through Tuesday.  A change is expected for Wednesday as a surface low moves in with a maritime front, and rising freezing levels.

Snowpack Summary

The storm slab is most reactive where it overlies a sun crust down ~30cm on steep solar aspects in the alpine. The Nov 6 crust is down 80-120cm with facets around the crust. Results vary; sudden planar-collapse; Comp test easy- deep tap test hard on the Nov. 6 crust.  The mid-pack is strong.

Avalanche Summary

Recently, wind loading is the trigger.  A few avalanches to 1.5-2.5 east of Summit along the highway were noted.  One cornice fall from Mt. Cheops did not propagate a slide.  No avalanches have stepped down to the Nov 6 crust, yet.

Confidence

Due to the number of field observations

Avalanche Problems

Storm Slabs

The storm snow is settling into a cohesive slab. It is most reactive on steep solar slopes in the alpine where it overlies a sun crust. Skiers have accidentally triggered avalanches on this layer that propagated across terrain.
Avoid convexities or areas with a thin or variable snowpack.Avoid steep Southerly aspects.

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 3

Wind Slabs

Strong southerly winds during last weeks storm transported snow, loading lee slopes and forming wind slabs. These wind slabs have been buried by new snow and may be difficult to recognize.
The recent snow may now be hiding windslabs that were easily visible before the snow fell.

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2