Avalanche forecast

South Columbia

Jan 11 – 12, 2022Avalanche Canada
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Avalanche danger

Thu
Fri
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Avoid large features and convex slopes. New snow and warm temperatures are increasing the avalanche danger, and an unpredictable persistent slab problem has been active the last few days.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2.5–3.5

    The early December crust can be found down 80 to 180 cm below the surface, with weak, sugary crystals (facets) on top of it.

    There were recent avalanches on this layer. See the avalanche summary for more details.

    Sorry for sounding like a broken record, but triggering this layer is a low-probability, high consequence scenario. A problem like this makes me hesitant to ride a big or committing feature.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1.5–2.5

    Continued snowfall and moderate southerly winds have formed slabs that can still be triggered by riders. In sheltered areas that previously held low density snow, new, reactive slabs may form as the weather warms up.

    If triggered, storm slabs in-motion may step down to deeper layers and result in very large avalanches. 

Confidence

Moderate - Uncertainty is due to the track & intensity of the incoming weather system. We are confident the likelihood of avalanche will increase with the arrival of the forecast weather.

Weather Forecast

Steady moderate snowfall and rising temperatures through the forecast period. Expect heavier snowfall and warmer temperatures in the Monashees and Valhallas on Wednesday and through the night. 

MONDAY NIGHT: Mostly cloudy. 2-5 cm of snow expected. Light southwest wind trending to strong at higher elevations. Treeline temperatures around -7 C.

TUESDAY: Overcast. 0-15 cm of snow expected (on the higher end of the range in the Monashees). Light to moderate southwest wind trending to extreme at higher elevations. Freezing level rising to around 800 m.

WEDNESDAY: Overcast. 5-15 cm of snow expected overnight, with another 10-30 cm through the day. Moderate southwest wind trending to extreme at higher elevations. Freezing level rising to around 1300 m.

THURSDAY: Overcast. 5-30 cm of snow expected overnight, and up to 5 cm more through the day. Light southwest wind trending to moderate northwest at higher elevations. Freezing level rising to around 1500 m.

Avalanche Summary

On Monday, several small skier triggered avalanches were reported across the region. Mostly windslabs, but a few loose dry on slopes that saw the sun, and one lingering storm slab that was sitting on a buried sun crust.

The persistent early December crust/facet layer has recently been active in this region.

 

On Monday, a few very large simultaneous remote triggered persistent slab avalanches were reported in this Mountain Information Network (MIN) report south of Kaslo. It reported as a near miss, triggered from 150 m away on northeast through southeast features around treeline. The crown was one meter deep and propagated 500 m wide.

On Friday, three naturally triggered size 2-3 avalanches on this layer were reported in mountain ranges just west of the Columbia river. They were reported at treeline and above on south and east aspects. Some were known to be windslab avalanches that stepped down to this deeper, persistent layer in a thin, rocky area. 

Snowpack Summary

Consistent snow and southwest wind has left us with a mix of settling storm snow and windslabs in the upper snowpack. As new snow falls and recent snow settles on top of faceted snow that formed during the colder weather last week, the upper meter of the snowpack may get a bit upside-down and become more likely to avalanche.

We're actively monitoring the early December crust. In some places, it's down 80 cm, while in wind-loaded terrain features it can be found as deep as 180 cm below the surface. It consists of faceted grains above a bulletproof crust formed by the Atmospheric Rivers of early December. There has been avalanche activity on this crust over the weekend.

Terrain and Travel

  • Don't be too cavalier with decision making, storm slabs may remain sensitive to human triggering.
  • The more the snowpack warms-up and weakens, the more conservative you`ll want to be with your terrain selection.
  • Storm slabs in motion may step down to deeper layers resulting in large avalanches.
  • The likelihood of deep persistent slab avalanches will increase with each day of warm weather.
  • Avoid terrain traps such as gullies and cliffs where the consequence of any avalanche could be serious.

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