Avalanche forecast

Purcells

Nov 19 – 20, 2011Avalanche Canada
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Archived · expired 15 years ago

Avalanche danger

Mon
Tue
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

This bulletin is based on limited data. Local variation in conditions and danger levels are likely to exist. To produce more accurate forecasts, we need information. Please send an email to [email protected]

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–3
    Strong southerly, then north-westerly, winds have shifted snow onto downwind slopes. Some reverse loading may occur from Northeast winds in areas that still have snow available for transport.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–3
    Weak snow at the base of the snowpack will take time to gain strength. Steep or exposed terrain should be treated with suspicion. No new info so will keep this problem in for now.

Confidence

Poor - Due to limited field observations

Weather Forecast

Sunday should continue to be cooler and drier in the morning. The next wave of precipitation should move on to the coast around mid-day Sunday and begin to affect the interior ranges Sunday night and into Monday. This region may be too far East to receive more than light to moderate precipitation. The exception may be the Dogtooth area which may see moderate to heavy precipitation combined with moderate to strong southwest winds.

Avalanche Summary

A cycle of natural avalanche activity was observed in Quartz Creek on Sunday the 13th. Wind slabs (20cm deep) and persistent slabs (60cm deep) were observed. Persistent slabs were propagating widely and running on a weakness towards the base of the snowpack. Observations are limited to the northern Purcells so I don't know if this kind of thing is still occurring here. We have no new reports of avalanches.

Snowpack Summary

There is significant variability in the snowpack across the region. Snowpack depth at treeline varies from around 40-130cm. Up to 50cm of snow fell late last week and over the weekend, which was redistributed by strong winds blowing first from the south and then from the north-west. A basal layer of facets was reported in the Dogtooth Range, with a weak interface between the lower facets and recent storm snow. Cold temperatures should cause continued facetting on the surface and in the basal layers.

Regions covered