Avalanche forecast

Purcells

Nov 27 – 28, 2018Avalanche Canada
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Avalanche danger

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

Recent new snow has improved riding quality. But avalanche hazard will linger after the storm.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    1–3
    A nasty combination of crust and sugary, faceted snow exists at the base of the snowpack in the alpine. This layer could produce avalanches on steep, smooth slopes in the alpine.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–2
    Recent new snow and wind will have set up storm and wind slab problems that are most likely to give problems on steep, smooth, north to east facing slopes.

Confidence

Low - Due to the number of field observations

Weather Forecast

TUESDAY NIGHT: Flurries with moderate southwesterly winds.WEDNESDAY: Occasional flurries with some clear spells. Moderate southwesterly winds. Freezing level around 1400 m.THURSDAY: Dry with a mix of sun and cloud. Light southwesterly winds. Freezing level around 1200 m.FRIDAY:    Dry with a mix of sun and cloud. Calm winds. Freezing level around 600 m.

Avalanche Summary

It's unlikely there was quite enough snow for much natural avalanche activity to have occurred during the storm on Monday or Tuesday. However, human-triggered avalanches will remain a concern on steep, smooth slopes for a few days after the storm ends. On Saturday, a large human triggered avalanche was reported in the South Columbia forecast region. The size 3 avalanche occurred on a steep, north aspect in the alpine and failed to ground, likely on the October crust. This avalanche is notable for the Purcells where we have a similar, but shallower snowpack than in the South Columbia, resulting in a higher possibility of impacting a weak layer near the ground. Find the MIN report here.

Snowpack Summary

Approximately 20 cm new snow fell in this area during the most recent storm, which will have been blown into wind slabs on exposed northerly and northeasterly slopes. In most places, there are two layers of feathery surface hoar being reported, one around 20cm below the surface and one around 35cm. One or both of these may be associated with a crust on south aspects. The most likely places to trigger one of these layers is in deeper snow areas in shady spots on smooth slopes. A final, prominent feature of the snowpack is a combination of a crust and underlying sugary, faceted snow found near the base of the snowpack. It may still be possible to release an avalanche on smooth slopes in the alpine.

Regions covered