Bulletin d’avalanche

Northwest Coastal

Jan 5 – 6, 2020Avalanche Canada
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Archivé · expiré 7 years ago

Danger d’avalanche

Tue
Wed
Alpin
4 · Fort
Limite forestière
4 · Fort
Sous la limite
3 · Marqué
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Points saillants

Another wave of snow and strong winds will keep the danger elevated through the weekend. Give the new snow a few days to settle and stabilize before pushing into bigger terrain.

Problèmes avalancheux

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Very Likely
    Taille
    1–3

    50-70 cm of recent storm snow followed by strong winds have likely formed deep pockets of storm slab in lee features in the alpine and treeline. On steep slopes in wind sheltered areas, loose dry avalanches are likely, especially on south aspects if the sun comes out Sunday. Even after natural storm cycle avalanche activity starts to taper off, storm slab avalanches will remain sensitive to human triggering.

Confidence

Moderate - Uncertainty is due to the track & intensity of the incoming weather system.

Weather Forecast

Saturday night: 10-25 cm of new snow. Strong southwest winds, approaching extreme at ridgetop. Alpine low temperatures around -7. Freezing level around 500 m.

Sunday: Mix of sun and cloud with scattered flurries bringing 5-15 cm of new snow. Moderate west winds. Alpine high temperatures around -6. Freezing level around 500 m.

Monday: Mix of sun and cloud with isolated flurries bringing up to 5 cm of new snow. Light to moderate northwest winds. Alpine high temperatures around -7. 

Tuesday: Mostly cloudy with isolated flurries bringing a trace of snow. Light variable winds. Alpine high temperatures around -8. 

Avalanche Summary

A widespread natural storm slab avalanche cycle is likely to have occurred throughout the region where more than 40 cm of snow fell on Friday.

On Saturday, storm slabs up to size 2.5 and loose dry up to size 2 were observed in the Shames area and the Skeena corridor. And windslab avalanches up to size 2.5 were reported in Bear Pass. Avalanches up to size 3 were reported from the neighboring Howson range during the storm on Friday.

Snowpack Summary

Snowfall overnight will bring storm snow depths to 50-70 cm. In the alpine, the storm snow has likely been highly wind affected. Expect to find deep wind loaded pockets below ridgetops and the lee sides of exposed features. 

The new snow fell on a temperature crust up to treeline and extensive windslab at alpine and treeline elevations. The underlying snowpack is overall quite well consolidated, with an average depth of around 2 m. Two layers of surface hoar are now buried 80-150 cm deep but with a lack of recent associated avalanche activity, appear to be trending towards dormancy.

Terrain and Travel

  • Watch for fresh storm slabs building throughout the day.
  • Continue to make conservative terrain choices while the storm snow settles and stabilizes.

Régions couvertes