Bulletin d’avalanche

Northwest Coastal

Dec 21 – 22, 2017Avalanche Canada
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Archivé · expiré 9 years ago

Danger d’avalanche

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

Watch for wind slabs in unusual places, including low elevation terrain.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–3
    At upper elevations, northwest has been the primary wind direction. At lower elevations, easterly outflow winds are expected. Watch for wind slabs in unusual places.

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    2–3
    This problem appears to be ongoing, particularly in areas around Stewart and to the north. Likely trigger points are in steep, rocky alpine terrain.

Confidence

Moderate - Wind effect is extremely variable

Weather Forecast

Kasiks (1435m):HN24 9cm; TMin -5; TMax 0; winds 30-50 NWShames (740m):6cm/6mm; TMin -5; TMax -3Bear River Ridge (1995m):Windy Upper (1490m):winds 30-60 W then NWEndgoal (370m):HN24 4cmSnowbank Mid (1065m):HN24 3cmRevision (1500m):20-35 W then NW

Avalanche Summary

Explosive control work on Tuesday and Wednesday managed to produce some large avalanches that failed on the crust buried at the end of October on north through east aspect alpine slopes in the Stewart area and north of Stewart. A natural storm avalanche cycle was observed last weekend up to size 2.5.

Snowpack Summary

The region picked up 20 to 60cm of storm snow last weekend accompanied by winds out of the southwest, west, northwest, and most recently the east. Since then, little additional snow has fallen, but cooler temperatures have kept snow dry and susceptible to being blown around by the wind. Wind slabs may rest on a melt freeze crust (reported to be 3 to 15cm thick), and there are reports there also may be surface hoar resting above this crust in sheltered locations. Below this crust the mid-pack is reported to be generally strong. You can expect to find a second prominent crust, which was buried at the end of October, 100 to 200cm below the surface. This lower layer may have associated facets, particularly in more shallow locations.

Régions couvertes