Avalanche forecast

Purcells

Mar 27 – 28, 2019Avalanche Canada
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Avalanche danger

Fri
Sat
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

A variable dose of new snow has resupplied avalanche problems in much of the region. Be mindful of avalanche danger increasing in sync with daytime warming.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5
    New snow and south winds formed new wind slabs at higher elevations during the storm. This problem increases with elevation and is highly variable throughout the region with new snow totals of a trace to 25 cm.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    1.5–2.5
    A few weak layers still exist within the snowpack. The recent hot weather may have influenced these layers, but time is needed to assess how much they have changed.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2
    New snow has resupplied our loose wet avalanche problem in much of the region. Rising temperatures and sunshine will destabilize surface snow on Thursday, especially on steep, sunny slopes. Larger avalanches become possible during peak warming.

Confidence

High -

Weather Forecast

Wednesday night: Mainly cloudy. Light to moderate southeast winds.Thursday: A mix of sun and cloud. Light variable winds. Alpine high temperatures around -2 with freezing levels to 1900 metres.Friday: Mainly sunny. Light northeast winds shifting northwest. Alpine high temperatures around 0 with freezing levels to 2100 metres.Saturday: Mainly sunny with cloud increasing over the day. Light southwest winds. Alpine high temperatures around 0 with freezing levels to 2100 metres.Overnight freezing levels will increase steadily during this period, dropping briefly each night to between 1000 to 1500 metres.

Avalanche Summary

No new avalanches were reported in the Purcells on Tuesday, but reports from neighbouring regions showed new snow from Tuesday's storm reacting to skier traffic, ski cutting, and explosives control with 10-25 cm-deep slabs propagating easily and widely over previous surface crusts. All aspects were represented in reports, with a focus on north to northeast aspects as a result of loading by southwest winds. Similar conditions are likely to exist in areas of the Purcells that received more than a skiff of new snow from Tuesday's storm. Looking forward, lingering wind slabs (in areas with new snow) may still react to skier triggering and may also become touchier with warming. In some areas an ample supply of new snow is in place to reinvigorate loose wet avalanche problems as sunshine and warming take hold each day. Where less new snow exists, loose wet activity may be slightly more subdued.

Snowpack Summary

Variable new snow amounts of a trace to 25 cm have accumulated above a surface of melt-freeze crust in most areas above 1500 metres. Below this elevation it buried variably moist or crusty surfaces. Precipitation as rain has continued to saturate the snowpack that is increasingly isothermal (slushy and cohesionless) and disappearing rapidly below about 1100 metres.The mid snowpack is generally consolidated and strong, but exceptions may exist on north aspects above 2000 m, where a gradually strengthening layer of faceted grains buried 40 to 60 cm deep may still be preserved below an overlying slab of old and hard wind-affected snow.The base of the snowpack is composed of weak faceted snow which may coexist with a melt-freeze crust. Only one very large persistent slab was reported to have failed at this layer during last week's warming event.

Regions covered