Avalanche forecast

South Rockies

Jan 22, 2019Avalanche Canada
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Archived · expired 8 years ago

Avalanche danger

Wed
Thu
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Watch for fresh winds slabs and avoid shallow spots and rocky terrain where triggering deeper weak layers is more likely.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1.5–2
    Recent snow fell on weak surface hoar and/or crusts and been redistributed by wind. The deepest and more reactive deposits will be in wind-loaded terrain.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    2–3
    Deeply buried weak layers remain a concern. These layers are more easily triggered in areas where the snowpack is shallow, such as near ridges and rocky terrain.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

MONDAY NIGHT: Cloudy with clear breaks. Light west wind. Alpine low -12, freezing level valley bottom.TUESDAY: Cloudy with isolated flurries, trace accumulation. Moderate to strong west wind. Alpine high -10C, freezing level valley bottom.WEDNESDAY: Cloudy with scattered flurries, 5-10 cm snow. Light to moderate west wind. Alpine high -6C, freezing level 1100 m.THURSDAY: Cloudy with sun and isolated flurries, trace accumulation. Light west-northwest wind. Alpine high -6C, freezing level 1200 m.

Avalanche Summary

A size 1.5 natural wind slab avalanche was observed in steep terrain on Sunday. Skier traffic produced a few small (size 1) avalanches in the new snow on Thursday.The most recent reports of larger avalanches are from over a week ago, when warm temperatures stressed the deeper layers in the snowpack and produced a few size 2 avalanches.

Snowpack Summary

Winds have redistributed up to 20 cm recent snow into wind slabs in the alpine and treeline. This new snow buried large surface hoar crystals and/or sun crusts, which could eventually develop into a touchy problem as snow accumulates. The most suspect terrain features will be steep slopes and rolls below 2000 m (where the largest surface hoar exists) and steep south-facing slopes in the alpine (where sun crusts exist). Large variability in snow depths still exists in the region, ranging from almost no snow to nearly 200 cm in some areas. For average snowpack areas, expect to find weak and sugary faceted snow around 50 to 100 cm deep, which extend to the ground. This weak bottom half of the snowpack has been the culprit for large avalanches in the region over the past few weeks.

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