Bulletin d’avalanche

South Coast Inland

Apr 23 – 24, 2023Avalanche Canada
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Archivé · expiré 3 years ago

Danger d’avalanche

Tue
Wed
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Points saillants

Check for signs of wind slab instability in steep terrain at higher elevations, especially around ridgetops. Watch for signs of loose wet instability, like snow that clumps together and pinwheels down the slope.

Use good travel habits, and evaluate each slope on a case by case basis. Field observations are very limited, and we are not certain about the exact avalanche problems you could encounter on your day in the backcountry.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–2

    Snowfall and moderate, southwest, high alpine winds continue to be forecasted for this region. With a lack of alpine weather stations, and very minimal field data, we are uncertain about the extent and reactivity of this wind slab development.

    Check for windslab hazard before committing to a steep or large slope. Use extra caution below ridgecrests and in cross-loaded features. Watch for signs of instability like shooting cracks, or recent avalanches.

    Small avalanches could step down to a layer of facets and crust buried 60 cm deep that could result in large avalanches.

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–1.5

    Reports of wet loose avalanches have continued through the recent stormy period. While the vast majority of these avalanches have been small (size 1), remember that wet loose avalanches are more dense, and harder to fight against. If you trigger a small avalanche in the wrong terrain, it can still have serious consequences.

Confidence

Low

Avalanche Summary

There are very few field observations coming from this forecast area. Remember that a lack of avalanche reports does not necessarily mean a lack of avalanche activity. We expect that riders could trigger wind slabs in steep lee terrain features at treeline and alpine elevations.

On Sunday in the Duffey Lake area, several small (size 1), naturally triggered loose wet avalanches were reported on steep, north facing slopes.

The most recent avalanches on the facet layer described in the Snowpack Summary occurred nearly two weeks ago (e.g., this MIN).

Snowpack Summary

A dusting of dry snow covers moist snow in the alpine, and wet surfaces or frozen crusts at treeline and below. Recent snow and southwest wind have likely formed wind slabs in leeward terrain features at high elevations.

A layer of facets and a crust buried in early April is found up to 60 cm deep at treeline and alpine elevations. This layer was the culprit of many large avalanches around April 12. It is suspected that this layer may have gained strength and bonded to the rest of the snowpack, but with limited field data from this forecast area, it remains an uncertainty for us.

The base of the snowpack remains faceted and weak. There are no reports of recent avalanche activity on this layer, but the concern remains for triggering large avalanches on steep and rocky slopes with a thin snowpack.

Cornices are large and looming at this time of year.

Weather Summary

If you are wondering why the freezing line and the snow line might be so different on some days, click here for more information:)

Sunday Night

Cloudy. 2-5 cm of snow expected. Snow/rain line around 1200 m. Light southwest ridgetop wind trending to moderate at very high elevations.

Monday

Mix of sun and cloud. Possible trace of snow/rain expected. Freezing level rising to 1800 m. Treeline low around -3°C. Light southwest ridgetop wind.

Tuesday

Mostly sunny. No new snow/rain expected. Freezing level rising to 2000 m. Treeline high around -1°C. Light southwest ridgetop wind.

Wednesday

Partly cloudy. Possible trace of snow/rain expected. Freezing level rising to 2600 m. Light southwest ridgetop wind trending to strong west at very high elevations.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Pay attention to isolated alpine features as well as cross-loaded features at treeline.
  • Carefully evaluate steep lines for wind slabs.
  • Pay attention to cornices and give them a wide berth when traveling on or below ridges.
  • A moist or wet snow surface, pinwheeling and natural avalanches are all indicators of a weakening snowpack.
  • Use caution above cliffs and terrain traps where even small avalanches may have severe consequences.

Régions couvertes