Bulletin d’avalanche

Coquihalla

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

Use good travel habits, and evaluate each slope on a case by case basis.

Look for signs of wind slab or wet loose instability before committing to large or steep terrain features.

Problèmes avalancheux

  • Wind Slabs

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

    Snowfall and moderate southwest ridgetop winds continue to be forecasted for this region. With a lack of alpine weather stations, and 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.

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    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 (up to size 1.5), 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.

    Wet loose avalanches may be less likely at low elevations, where most of the snowpack has already experienced several heavy rainfalls and significant warming, but if you are finding, deep, slushy, loose snow, use extra caution on steep slopes.

Confidence

Moderate

Avalanche Summary

On Saturday and Sunday in the Coquihalla area, daytime warming caused numerous naturally triggered wet loose avalanches in steep terrain. The largest of these avalanches was a size 2.

Use plenty of caution along alpine ridges, where cornices may be large.

Snowpack Summary

A dusting of dry snow covers a mixed bag of surfaces. In the alpine: dry, settling snow on shaded aspects, and moist snow on solar aspects. At treeline and below: moist snow or frozen crusts.

Southwest wind has likely formed wind slabs on leeward terrain features in the high alpine, but field observations are limited.

The recent snow sits over a series of moist or wet layers that have been frozen and thawed again a few times.

The remainder of the snowpack is strong with varying hard snow layers and bonded melt-freeze crusts. Cornices are large along many alpine ridges.

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. Light snow/rain, 2-5 mm, up to 10mm in the southwest corner of the forecast area, close to Chilliwack. Snow/rain line around 1100 m. Treeline low around -3°C. Moderate southwest ridgetop wind.

Monday

Low cloud. Light snow/rain expected. as much as 7 mm in the southwest corner of the forecast area, close to Chilliwack. Snow/rain line around 1250 m. Treeline high around -1°C. Light to moderate west or southwest ridgetop wind.

Tuesday

Mostly sunny by the afternoon. Trace of snow/rain expected. Freezing level rising to between 1800 and 2200 m. Light to moderate southwest ridgetop wind.

Wednesday

Mostly sunny, increasing cloud through the day. No new snow/rain expected. Freezing level rising to 3000 m. Moderate to strong west or southwest ridgetop wind.

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.
  • 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.
  • Pay attention to cornices and give them a wide berth when traveling on or below ridges.

Régions couvertes