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Avalanche Forecast

Archived

Dec 17th, 2021–Dec 18th, 2021

Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

South Columbia.

Avoid "thick to thin" areas and steep roll overs, Especially in treeline terrain. Persistent slabs are challenging to manage, if in doubt choose conservative terrain. If you observe more than 30cm of new snow consider the hazard rating to be high in the treeline and alpine. 

Confidence

Moderate -

Weather Forecast

Friday night: No new snow expected. Moderate Southwest winds and Low of -17 at 1600m.

Saturday: a storm arrives bringing up to 30cm of new snow with the greatest snowfall in the Monashees. Winds will be strong from the Southwest. High of -9 at 1600m.

Sunday: some light snow in the morning. Strong Southwest winds in the morning becoming light in the afternoon. High of -8 at 1600m.

Monday: some flurries in the afternoon with moderate Southwest winds. High of -11 at 1600m.

Avalanche Summary

On Tuesday one skier triggered size 1.5 was reported on a North aspect at 2200m. This avalanche occurred on the facets above the early December crust. The avalanche was triggered by the sixth skier to enter the slope.

Snowpack Summary

The incoming weather will form new windslab in the alpine and treeline.

The defining feature of the snowpack is a widespread crust that reaches as high as 2400 m and now sits 30-100 cm below the surface. In some places overlying snow is well-bonded to the crust but in others weak faceted grains have been observed above it. The faceting is most prominent in the treeline where the crust is thinner. We expect the incoming weather to increase the likelihood of triggering this layer.

Average snowpack depth at treeline is 200cm.

Terrain and Travel

  • Be careful as you transition into wind affected terrain.
  • Be aware of the potential for large avalanches due to the presence of a persistent slab.
  • In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.

Problems

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.