Bollettino valanghe

Northwest Inland

Mar 23 – 24, 2013Avalanche Canada
Vedi sulla mappa
Archiviato · scaduto 14 years ago

Pericolo valanghe

Mon
Tue
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
Apri la mappa completa

In sintesi

The March 9th persistent weakness is very sensitive to human triggering and has produced frighteningly large avalanches.  Stay conservative in your approach to the mountains this weekend

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible - Likely
    Dimensione
    2–5
    Large well developed cornices loom over many slopes. Cornices may become more sensitive on slopes receiving direct sun. It's likely that cornice failure will initiate large avalanches failing on the March 09 persistent weak layer.

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible - Likely
    Dimensione
    2–7
    A 30 - 60cm slab now rests on the March 09 surface hoar/crust combo. This consolidated slab is very touchy and is subject to remote triggering from great distances. A very cautious approach to mountain travel is appropriate at this time.

Confidence

Fair - Due to limited field observations

Weather Forecast

Synopsis: Fine weather for the Sunday. A very weak system will bring cloud and flurries for Monday and Tuesday.Sunday: Clear and sunny. Daytime alpine temperatuers around -5, but feeling warmer in the sun. Light winds.Monday and Tuesday: Cloudy with occasional flurries. Afternoon freezing level rising to around 1100 m. Southeast winds to 30 km/h.

Avalanche Summary

No new avalanches were reported on Friday. On Thursday, human-triggered avalanches were reported running on a the March 9th surface hoar layer on north and northwest aspects. Natural avalanches up to size 2 were also observed on lee slopes below steep ridge lines. On Wednesday, there was a natural cycle to size 3. Skiers were remote triggering large destructive avalanches (size 2.5) from as far as 800m away. It has been an active recent period, with numerous avalanches reported to have failed on the March 9th layer over the past week.

Snowpack Summary

35 - 65 cm of recent snow rests on a variety of old snow surfaces, including crusts, previous wind slabs and a buried surface hoar layer (March 9th). The March 9th surface hoar layer has been very touchy in many areas and many large avalanches have released on it. While natural avalanche activity on this layer has diminished, snowpack tests showing very easy shears reinforce this layer should not yet be trusted. The distribution of the surface hoar is slightly variable and it may not exist, or be reactive, in every drainage. Where it does exist, it appears to be present at all elevations, but is likely to pose the biggest threat in the alpine. Recent reports indicate it has been more reactive on south through west aspects, but I wouldn't necessarily trust steep north or east facing slopes at this time either. I suspect cornices have become well-developed and could easily become unstable during periods of warm weather or on slopes receiving direct sun. The mid snowpack is generally well settled and strong.

Regioni coperte