Bollettino valanghe

Northwest Inland

Feb 18 – 19, 2013Avalanche Canada
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Archiviato · scaduto 14 years ago

Pericolo valanghe

Wed
Thu
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
Apri la mappa completa

In sintesi

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible - Likely
    Dimensione
    1–4
    The region received a small shot of new snow Monday which is quickly being formed into new soft sensitive wind slabs.  These new wind slabs are covering potentially deep old wind slabs that may still be sensitive to triggering by snow riders.

  • Cornices

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible - Likely
    Dimensione
    1–5
    The recent snow and wind have been building cornices on lee features.  These cornices are likely weak and may fail at anytime.  Cornice failure has the potential to trigger large avalanches.

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely - Possible
    Dimensione
    2–7
    Buried beneath the new snow sits a surface hoar/crust/facet weakness. This may be sensitive to rider triggers in steeper sheltered terrain or over convex rolls, especially at treeline and below treeline elevations.

Confidence

Poor - Due to limited field observations

Weather Forecast

Tuesday: Freezing Level: 500m rising to 750m, Wind: Light W, No significant precip.Wednesday: Freezing Level: 500m Wind: SW, initially moderate increasing to strong by sundown.  10 - 15 expected during the day.Thursday: Freezing Level: 500m Wind: Strong SW backing off of to moderate SW in the evening.  10 - 20 cm expected during the day.

Avalanche Summary

A wind loaded NE facing slope around 1400m released naturally to ground resulting in a size 3 avalanche.

Snowpack Summary

Depending on the location, light to moderate amounts of new snow have been shifted into wind slabs and overlie older wind slabs that formed earlier in the week. Below treeline, light rain and warm temps have saturated the surface which has left a crust below around 1000m. In general, between 30-60cm of storm snow sits over a variety of old surfaces which include facets, crusts and isolated pockets of surface hoar (sheltered treeline and below treeline). There is very limited information about the nature of this interface, with the only results suggesting reactivity in sheltered, shady treeline and below treeline slopes (preserved surface hoar). I would stress the importance of digging down to find and test weak layers.A strong mid-pack currently overlies a weak base layer of facets/depth hoar. It is worth noting that the snowpack in general is quite shallow compared to averages; triggering the basal weakness may still be possible from thin spots, rocky outcrops or under the weight of larger triggers such as cornice fall.

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