Avalanche Forecast

Issued: Jan 17th, 2020 4:00PM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is moderate. Known problems include Wind Slabs and Persistent Slabs.

Avalanche Canada mconlan, Avalanche Canada

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Expect to find touchy wind slabs in exposed terrain features. There still remains a possibility of triggering a buried weak layer in parts of the region.

Summary

Confidence

High -

Weather Forecast

FRIDAY NIGHT: Increasing clouds, light southwest wind, alpine temperature -16 C, freezing level below valley bottom.

SATURDAY: Cloudy with snowfall, accumulation 5 to 10 cm, moderate to strong southwest wind, alpine temperature -13 C, freezing level below valley bottom.

SUNDAY: Cloudy with snowfall, accumulation 5 to 10 cm, moderate to strong southwest wind, alpine temperature -7 C, freezing level below valley bottom.

MONDAY: Cloudy with snowfall, accumulation 5 to 10 cm, moderate to strong southwest wind, alpine temperature -5 C, freezing level 800 m.

Avalanche Summary

Many small storm and wind slab avalanches were reported in the region on Thursday. They were most often on northwest to northeast aspects and at treeline and alpine elevations. They generally ranged from 10 to 50 cm deep. 

Last weekend there were a few notable reports of large persistent slab avalanches in the Selkirks and the northern tip of the Monashees (near Blue River and Valemount). The avalanches failed on a 100 cm deep surface hoar layer on north and east aspects between elevations of 1200 to 2100 m. Observations suggest this layer has trended towards being less reactive. There is uncertainty on whether the layer will wake up with more snowfall.

Snowpack Summary

Fresh wind slabs can be found in exposed terrain on all aspects, while around 30 cm of recent soft snow exists in sheltered terrain. A layer of surface hoar is now buried 80-150 cm below the surface and could still be a concern in certain parts of the Selkriks and the northern end of the Monashees. A facet/crust layer from late November lingers near the bottom of the snowpack and has occasionally been reactive in isolated shallow snowpack areas.

Terrain and Travel

  • Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
  • Be aware of highly variable recent wind loading patterns.
  • Approach steep open slopes at and below treeline cautiously, buried surface hoar may exist.

Problems

Wind Slabs

An icon showing Wind Slabs

A shift in wind direction from northeast to southwest means that wind slabs may be found on all aspects. Wind slabs have been recently reported as easy to trigger and having the potential to propagate far. The most likely place to find this problem is in exposed terrain features at and above treeline, particularly near ridges.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Persistent Slabs

An icon showing Persistent Slabs

A layer of surface hoar buried 80 to 150 cm deep could still be triggered on certain slopes around treeline elevations in the Selkirks and the northern tip of the Monashees.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Jan 18th, 2020 5:00PM

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