Bulletin d’avalanche

Kootenay Boundary

Feb 16, 2019Avalanche Canada
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Archivé · expiré 8 years ago

Danger d’avalanche

Sun
Mon
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
3 · Marqué
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Points saillants

Human-triggered avalanches are likely this weekend as the new snow continues to be very reactive. Stick to simple well-supported terrain.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2
    Strong wind has blown recent snow into touchy slabs on all elevations and aspects. The problem is further complicated by buried surface hoar in the trees.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1.5–2.5
    Two buried surface hoar layers are in the upper meter of the snowpack; one is down 40 to 60 cm and has been recently active, the other is down 60 to 80 cm. These layers are at a time of enhanced sensitivity as they adjust to the new load.

Confidence

Moderate - Forecast snowfall amounts are uncertain on Saturday

Weather Forecast

A low pressure system will linger over the southeast corner of the province until Sunday morning, which will bring steady low density snowfall to the region. Exact amounts are uncertain.FRIDAY NIGHT: Light flurries with 5-10 cm of low density snow, moderate west wind, alpine temperatures drop to -10 C.SATURDAY: Light flurries continue with another 5-10 cm of low density snow, moderate west wind, alpine high temperatures around -8 C.SUNDAY: Scattered flurries in the morning then clearing in the afternoon, light wind, alpine high temperatures around -12 C.MONDAY: Mix of sun and cloud, light north wind, alpine high temperatures around -14 C.

Avalanche Summary

Slab avalanche activity has been reported daily since Tuesday's storm, and is expected to continue into the weekend with the ongoing snowfall.Preliminary reports from Friday, include numerous large (size 2-2.5) explosive triggered storm slabs on south aspects.On Thursday, strong wind formed fresh wind slabs that produced several size 1-2 natural avalanches. The wind slabs were very reactive to human triggering on all aspects. Two large (size 2) skier-triggered slab avalanches were reported at treeline elevations with crowns up to 80 cm thick. Numerous smaller (size 1) skier-triggered wind slabs were also reported, including some triggered from a distance (remotely).

Snowpack Summary

A total of 30 to 50 cm of fresh snow has fallen over the past few days and has been very reactive to human triggering. A strong wind event on Thursday formed fresh wind slabs in exposed terrain (see this MIN report), while low density snow may still be found in sheltered areas. The new sits on a variety of old surfaces that include a sun crust on southerly aspects, variable wind-affected snow, and weak feathery surface hoar crystals at and below treeline. The snowpack hosts two buried surface hoar layers. The February 1st surface hoar is down 40 to 60 cm and has been recently reactive to human triggers. The mid-January surface hoar is 60 to 100 cm below the surface. This deeper layer of surface hoar is most prevalent below treeline on shady aspects, but it does not seem to be a widespread problem in the region. Below that, the snowpack is well settled.

Régions couvertes