Avalanche forecast

Purcells

Mar 17 – 18, 2023Avalanche Canada
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Avalanche danger

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

Sun and warming continues on Saturday. Minimize your exposure to steep slopes facing the sun.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    Recent snow from earlier in the week has been redistributed by primarily southwest wind into alpine and treeline lee terrain.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    1.5–3

    Numerous weak layers from January and February exist at all elevations on a variety of aspects. On shaded slopes, these layers generally present as surface hoar, and on sun-exposed slopes they present as facets and a crust.

    Be aware these layers can be remotely triggered (from a distance).

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2.5–4

    The base of the snowpack remains very weak. Very large human triggered avalanches are possible at treeline and above.

Confidence

Moderate

Avalanche Summary

On Wednesday there were still reports of a few natural and explosives triggered storm and wind slab avalanches to size 2 and 3 which were suspected of having stepped down to deeper layers of facets.

Earlier in the week several naturally triggered size 2.5-3 deep persistent slab avalanches were observed in the Dogtooth range running in steep rocky terrain. Evidence of a size 4 natural deep persistent slab avalanche was observed in the western Purcells.

If you head out in the backcountry, let us know what you are seeing by submitting a report to the Mountain Information Network.

Snowpack Summary

15-30 cm of wind-affected storm snow falling earlier in the week overlies wind-affected snow in open areas, facetted snow in sheltered areas and a thin sun crust on steep solar slopes.

Buried surface hoar can be found 70-90 cm deep in sheltered terrain features. A thin sun crust exists at the same depth on steep south-facing terrain.

The lower snowpack is made up of a widespread layer of large, weak facets and/or depth hoar crystals. This weak layer has been responsible for a number of recent very large, destructive avalanches and will continue to be a concern.

Weather Summary

Friday Night

Mainly clear. Treeline temperature -9 °C. Wind light southwest. Freezing level at valley bottom.

Saturday

Mainly sunny with cloudy periods. Treeline temperature -2 °C. Wind light southwest. Freezing level rising to 2000m.

Sunday

Mix of sun and cloud. Treeline temperature -1 °C. Wind light southeast. Freezing level rising to 2000m.

Monday

Mainly cloudy with scattered flurries. Treeline temperature -4 °C. Wind light east. Freezing level 1500m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Be especially cautious as you transition into wind affected terrain.
  • Minimize exposure to sun-exposed slopes when the solar radiation is strong.
  • Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
  • Avoid areas with a thin or variable snowpack.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.

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