Bulletin d’avalanche

Lizard-Flathead

Jan 3, 2018Avalanche Canada
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Archivé · expiré 9 years ago

Danger d’avalanche

Thu
Fri
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
3 · Marqué

Points saillants

We're into a tricky period as a critical amount of storm snow settles (into a slab) and sits on a buried weak layer. Keep your terrain choices on the conservative side until conditions stabilize.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–3
    Moderate winds have created fresh wind slabs in the alpine.
  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–3
    A weak layer composed of surface hoar and/or crusts is buried 40-70 cm below the surface. This layer continues to be very reactive to human triggers and may not improve anytime soon.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

Dry with gradually warming alpine temperatures during the week. Cold in the valley bottoms. WEDNESDAY: Cloudy with sunny breaks. Ridge wind light west. Alpine temperature -5. Freezing level surface.THURSDAY: Mix of sun and cloud. Ridge wind light southwest. Alpine temperature -5. Freezing level surface.FRIDAY: Cloudy with isolated flurries. Ridge wind light west. Alpine temperature -3. Freezing level surface.

Avalanche Summary

We've had several natural avalanches (and the greatest concern) between 1600m and 1800m on steep or open glades on all aspects... this is where the mid December layer has been most active. On Tuesday we had reports of several small loose avalanches triggered by the sun and warmer temperatures in the alpine. On Sunday we had reports of small features being reactive to sled cutting. See here for the MIN report - great information from a low-consequence slope. On Sunday, an explosives-triggered Size 2.5 persistent slab avalanche was reported on a south east aspect at 1700m near Fernie, running on the mid-December surface hoar layer (down 65cm in that location).

Snowpack Summary

The mid-December layer (with variable distribution, but commonly found between 1600m and 1800m) is now buried 40-70 cm below the surface. This layer includes crusts on south and west facing slopes and feathery surface hoar in sheltered areas at and below treeline, and has been producing moderate, sudden results in recent snowpack tests.At higher elevations, winds (at times strong from the south west) have modified the snow pack, creating an "upside-down" slab layer with stiffer snow on top of softer snow.The lower snowpack is generally well settled with a thick prominent crust that was buried near the end of November.

Régions couvertes