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Avalanche Forecast

Archived

Jan 10th, 2021–Jan 11th, 2021

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

Regions

North Columbia.

A bit of new snow with strong wind will keep upper elevation wind slabs fresh on Monday. They will likely be thin but reactive, especially to human triggers.

Confidence

Moderate -

Weather Forecast

Sunday night: Flurries, up to 5 cm, moderate south wind, freezing level valley bottom.

Monday: Flurries, 5-10 cm, moderate to strong southwest wind, alpine high -6, freezing level 1200 m.

Tuesday: Flurries, up to 5 cm, moderate to strong southwest wind, alpine high -5, freezing level 1000 m.

Wednesday: Snow, 10-20 cm, moderate southwest wind, alpine high -5, freezing level 1200 m.

Avalanche Summary

A few reports of mostly minor solar triggered loose snow avalanches came in on Saturday afternoon. The occasional size 1 skier triggered wind slab is still being reported here and there.

Snowpack Summary

Small amounts of new snow fall on surface hoar in many areas and a thin crust on solar aspects. Previous moderate to strong winds have created variable wind effect at wind exposed elevations. 

A couple of persistent weak layers exist in the upper to mid snowpack:

  • The upper layer, found 50-80 cm down, is a spotty layer of surface hoar at treeline and below. 
  • The lower layer, found 90-150 cm down, is widespread and can present as surface hoar and/or a crust.

Avalanche activity on these layers has dwindled since last week and snowpack tests results have been moderate to hard planar, but still showing some propagation. Incoming snowfall in the forecast for this week will add additional load to these layers and may shed some light on whether they will remain a concern.

Terrain and Travel

  • Fresh wind slabs will likely form throughout the day, diligently watch for changing conditions.

Problems

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.

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.