Bulletin d’avalanche

Long Range Mountains

Feb 4 – 5, 2023Avalanche Canada
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Archivé · expiré 4 years ago

Danger d’avalanche

Mon
Tue
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
Sans niveau

Points saillants

In the wake of the storm, stick to simple terrain on Sunday. As fair weather settles in this week and inspires you to explore, be sure to start small and ease into terrain cautiously. Wind slabs are likely to remain triggerable by riders and uncertainty around a buried weak layer (and its potential to produce large avalanches) is on our minds.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1.5–2.5

    Recent snow and strong wind have formed wind slabs in leeward terrain features. Identify wind slabs by looking for stiff or drifted snow. Typical places to find them include beneath ridge crests and roll-overs and beside protruding features on cross-loaded slopes. Wind slabs may remain triggerable by riders for several days after natural avalanche activity subsides.

  • Cornices

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1.5–2.5

    Cornices have grown with the recent snow and wind. Give cornices a wide berth when travelling on or below ridges. Cornice falls can be dangerous on their own and they can trigger slab avalanches on slopes below.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    2–3

    A poorly bonded layer of faceted particles sits over a slippery crust ~50-150 cm deep. It has shown reactivity in recent snowpack tests and if triggered, it has potential to produce large, destructive avalanches.

Confidence

High

Avalanche Summary

We expect a widespread natural storm slab avalanche cycle to have occurred during the storm Friday and Saturday. Rider-triggered wind slab avalanches will remain likely for a few days after the storm.

Prior to this storm, recent avalanche observations have been limited to small wind slabs and cornice falls reported by our field team.

If you're heading out into the mountains, please consider sharing your observations on the Mountain Information Network!

Snowpack Summary

30-60 cm of new snow has been redistributed by strong northwesterly to westerly winds. Expect to find deep wind slabs on leeward aspects, and scouring on exposed windward aspects. After a milder storm over Sunday night, wind-ravaged surfaces may be blanketed by 5-15 cm of fresh snow.

The mid snowpack consists of 30-100 cm of recent January snow, poorly bonded to a crusty underlying lower snowpack.

Weather Summary

Saturday night

Intense localized snow squalls 3-5 cm per hour accompanied by strong northwesterly wind gusting 110 km per hour through the evening. Snowfall and wind easing mid night. Temperature -12 to -15 C.

Sunday

Scattered flurries through the day, intensifying in the evening as the next system approaches. Westerly wind 30 km/h switching southwest and increasing in the afternoon. Temperatures rising through the day, peaking around -5 C overnight.

Monday

5-15 cm of new snow overnight, clearing to a mix of sun and cloud. Light westerly wind. Alpine temperatures near -5 C in the morning dropping to -12 C through the day.

Tuesday

Sunny, light easterly wind, alpine high temperature around -10 C.

A quiet stretch of weather until late in the week.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Continue to make conservative terrain choices while the storm snow settles and stabilizes.
  • Start with simple terrain and gather information before thinking about more committing features.
  • Avoid freshly wind loaded terrain features.
  • Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
  • Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.

Régions couvertes