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Archived

Avalanche Forecast

Dec 21st, 2021–Dec 22nd, 2021
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
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
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
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Glacier.

Avalanche activity will spike during periods of heavy snowfall and strong, gusting winds.

Choose conservative terrain during the storm, and wait to explore more challenging terrain once things have calmed down this weekend.

Weather Forecast

The snow returns, to be replaced by cold, Arctic air for Christmas

Tonight: Flurries, 10cm, Alpine low -11*C, light SW winds

Wed: Snow, 15cm, Alpine high -7*C, light/gusting strong SW winds

Thurs: Snow, 13cm, Alpine high -6*C, light/gusting strong W winds

Fri: Flurries, 5cm, temps dropping to -18*C, light winds

Snowpack Summary

Storm snow will be landing on cold, faceted surfaces. Cold wx has sapped the strength/stiffness from wind slabs. The Dec 1 crust, down 70-120cm, and can be found up to 2300m. Facets (loose, sugary crystals) have been found above and below this crust. There is concern of triggering this layer in shallow, wind-scoured areas, especially at tree-line.

Avalanche Summary

Natural avalanche activity has been quiet the last couple of days, but will ramp up with the next storm. Natural avalanches will peak during periods of heavy snowfall and strong winds.

Snowpack tests continue to give sporadic sudden results on the Dec 1 crust, particularly in shallower snowpack areas at tree line.

Confidence

Avalanche Problems

Storm Slabs

The incoming storm snow is arriving with moderate winds and is warmer than the underlying snow, meaning a cohesive slab may form on an unsupported surface. Fresh slabs at ridge-crest and exposed cross-loaded slopes should be easy to trigger.

  • Use caution in lee areas. Recent wind loading has created slabs over weaker snow.
  • If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.

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

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 2.5

Loose Dry

More fresh snow on top of sugary, loose snow will encourage plenty of sluffing in steeper terrain. Be aware of terrain traps (gullies, tree wells, etc), so as not to get pushed/sucked into them by loose avalanches.

  • Use caution above cliffs and terrain traps where small slab avalanches may have severe consequences.
  • Be careful of loose dry power sluffing in steep, confined or exposed terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 1 - 2

Persistent Slabs

The Dec 1st crust is buried by ~100 cm of snow and is of most concern in shallow, windward areas around tree-line. It seems to be unreactive at the moment, but with increasing load it could wake up.

  • Avoid steep convexities or areas with a thin or variable snowpack.
  • If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Unlikely - Possible

Expected Size: 1.5 - 3