Bulletin d’avalanche

Coquihalla

Feb 2 – 3, 2023Avalanche Canada
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Archivé · expiré 4 years ago

Danger d’avalanche

Sat
Sun
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Points saillants

Watch for fresh, reactive wind slabs on north and east facing slopes in the alpine and treeline. Be especially cautious of wind slabs in steep, unsupported, and convex terrain features.

Problèmes avalancheux

  • Wind Slabs

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

    Southwesterly winds are distributing 5 - 10 cm of available snow into fresh wind slabs at higher elevations. New wind slabs bury a variety of wind-affected surfaces including stiff wind slabs on southerly slopes from last week's northerly outflow winds. Wind slabs may be reactive to human triggering where they overlie a slick crust. Watch for signs of instability like whumpfing, hollow sounds and shooting cracks.

Confidence

High

Avalanche Summary

On Sunday, a skier accidental wind slab avalanche was reported on a south-facing slope at 1800 m. This avalanche was 70 cm deep and is suspected to have slid on the Jan melt-freeze crust. Check out the MIN for a detailed report.

Whumpfing on stiff wind slabs is being reported at upper treeline and alpine elevations.

Thank you for the MIN's, please continue to post your reports and photos to the Mountain Information Network.

Snowpack Summary

This week moderate winds varying in direction have affected all exposed areas at alpine and treeline, scouring slopes and creating pockets of stiff wind slabs. A breakable crust exists on the surface at lower elevations and on steep solar aspects to 1800 m. Softer snow still exists in sheltered areas at treeline and below.

A melt-freeze crust from mid-January is found down 30-40 cm in many areas but up to 70 cm in wind-loaded places. Isolated weak layers may exist within the middle and lower snowpack below this, but the thick crusts sitting above them make triggering avalanches on these layers unlikely.

Snowpack depths are 150 to 200 cm at treeline and taper rapidly below 1500 m.

Weather Summary

Wednesday night

Mostly cloudy with clear periods. Southwesterly ridgetop winds 30 to 40 km/h. Treeline temperatures -2 ˚C. Freezing levels 1000 m.

Thursday

Mix of sun and cloud. Southwesterly ridgetop winds 40 to 60 km/h. Treeline temperatures -1 ˚C. Freezing levels 1400 m.

Friday

Cloudy with isolated flurries, 1-5 cm accumulation. Southwesterly ridgetop winds 40 to 60 km/h. Treeline temperatures -1 ˚C. Freezing levels 1400 m.

Saturday

Cloudy with scattered flurries, 1-5 cm accumulation. Southwesterly ridgetop winds 40 km/h. Treeline temperatures -1 ˚C. Freezing levels 1500 m.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Wind slabs may be poorly bonded to the underlying crust.
  • Use ridges or ribs to avoid areas of wind loaded snow.
  • Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.

Régions couvertes