Bulletin d’avalanche

South Columbia

Feb 26 – 27, 2013Avalanche Canada
Voir sur la carte
Archivé · expiré 14 years ago

Danger d’avalanche

Thu
Fri
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
3 · Marqué
Ouvrir la carte complète

Points saillants

Difficult and dangerous conditions remain in the backcountry at this time. Choose cautious and conservative routes.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–5
    Snow and wind on Sunday night adds to an ongoing storm instability. Watch for increased slab reactivity in wind-affected terrain. In sheltered areas, the new snow may also react as a loose dry avalanche.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    2–6
    Numerous large avalanches are failing on a weak and reactive layer of surface hoar which now lies up to 100cm below the surface. Triggering this weakness may result in surprisingly large avalanches.

Confidence

Fair - Timing, track, or intensity of incoming weather is uncertain on Friday

Weather Forecast

Synopsis: Mostly dry until Friday, when a Pineapple Express is likely to impact this region with warm temperatures and moderate (but prolonged) precipitation amounts.Wednesday and Thursday: Generally dry but flurries possible. Freezing level around 1300 m. Winds southwest, mostly light, increasing to strong on Thursday afternoon.Friday: Moderate snow/rain. Freezing level up to 2000 m. Southwesterly ridgetop winds to 60 km/h.

Avalanche Summary

A large avalanche was remotely triggered from a flat ridge on Tuesday, with a fracture depth of 130 cm. On Monday, numerous natural and human-triggered avalanches were reported up to size 2, mostly running on the February 12th surface hoar.The number, size, and destructive potential of recent avalanche events speak to the touchy nature of the persistent avalanche problem. I would expect human triggering at this persistent interface to be a very real possibility throughout the week.

Snowpack Summary

Moderate to locally heavy snowfall on Sunday adds to ongoing potent storm instabilities which seem to be most reactive as a wind slab in exposed terrain or as loose snow in more sheltered areas. A weak surface hoar layer which was buried on February 12th now exists up to a metre below the surface in many places. The highly variable and destructive nature of this persistent weakness remains a primary concern for professionals in the region. This interface has also shown reactivity on southerly aspects where a sun crust also exists. The mid to lower snowpack are generally strong and well settled. I anticipate significant cornice growth with the current weather pattern, and expect them to be weak and potentially destructive.

Régions couvertes