Avalanche forecast

Purcells

Jan 19, 2019Avalanche Canada
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Archived · expired 8 years ago

Avalanche danger

Sun
Mon
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

The Purcell snowpack is still scary and requires conservative terrain choices. Read the Forecaster's Blog about the region for more details here...

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–1.5
    New snow is gradually accumulating above weak surface hoar and/or crusts. Wind loaded slopes may have enough snow above this layer for small avalanches.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2.5–3.5
    People have recently triggered destructive avalanches on buried weak layers. This problem will exist for a while to come. These layers are more easily triggered in areas where the snowpack is shallow, such as near ridges and rocky terrain.

Confidence

High -

Weather Forecast

FRIDAY NIGHT: 5-10 cm of snow, moderate southwest wind, alpine temperatures drop to -10 C.SATURDAY: Flurries easing throughout the day with another 5 cm of snow, strong southwest wind, freezing level climbing to 1200 m, alpine high temperatures around -5 C.SUNDAY: Mostly cloudy then clearing in the afternoon, moderate west wind, freezing level climbing to 800 m, alpine high temperatures around -7 C.MONDAY: Mix of sun and cloud, light northwest wind, alpine high temperatures around -8 C.

Avalanche Summary

The likelihood of triggering large avalanches is still elevated due to the weak nature of the snowpack. Watch out in thin snowpack areas, where the likelihood of triggering deeper layers is the highest.On Thursday, explosives triggered numerous large cornices on north alpine ridges. On Wednesday, a large (size 3) naturally triggered avalanche was observed on a southeast aspect in the alpine near Golden. On Monday, several large (size 2) avalanches were observed throughout the region, some releasing on weak faceted grains near the base of the snowpack. On Sunday, a large (size 3) avalanche ran full-path on a southwest aspect in the alpine near Golden.Last weekend, a group of snowmobilers triggered a fatal avalanche near Invermere, also on the basal weak faceted grains. The avalanche was on a southerly aspect and ran approximately 900 to 1100 m. Two snowmobilers were caught. See here for more information.

Snowpack Summary

The snowpack is weak and touchy in large portions of the Purcells, with very large avalanches being reported on a regular basis. This type of weak snowpack could stick around for months. Read more here. 5-20 cm of new snow is burying 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).The weak nature of the snowpack lies at depth. There is a weak layer around 80 to 120 cm deep, composed of sugary faceted grains, feathery surface hoar, and a sun crust. The base of the snowpack is also composed of weak faceted grains in many parts of the region. Humans have and will continue to be able to trigger these layers in areas where the snowpack is shallow.

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