Bollettino valanghe

Northwest Inland

Jan 28 – 29, 2013Avalanche Canada
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Archiviato · scaduto 14 years ago

Pericolo valanghe

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

In sintesi

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–4
    New snow and strong shifting winds will build touchy wind slabs that are likely found behind terrain breaks such as ridges and ribs. Hollow sounds and cracking snow is a good indicator of unstable snow.

  • Deep Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely - Possible
    Dimensione
    2–5
    A deeply buried weak layer near the base of the snowpack could be triggered by large loads such as a cornice collapse or from a thin-spot trigger point.

Confidence

Fair - Due to limited field observations

Weather Forecast

Overnight Monday & Tuesday: Moderate Northerly wind backing to strong Westerly or Southwest. Around 10 cm of additional snow with continued cold temperatures (below freezing all elevations). Wednesday: Continued wind: moderate to strong from the west or northwest, with another 5cm of snow and just slightly warmer to around -7 C in the alpine (freezing level climbing to 400m or so).Thursday: Winds finally easing off and backing to the South, continued unsettled with continued light precipitation and just slightly warmer than Wednesday.

Avalanche Summary

Recent reports are of sluffing from steep terrain and small slabs (up to size 2 which isn't that small) forming in pockets behind ridges and ribs. I expect the number and size of windslab avalanches will increase with forecast wind, even if there isn't very much additional new snow.

Snowpack Summary

HST 20 cm building slabs lee SW. Wind should veer to W or NW.Prev Entry (Shannon Jan 27): Variable accumulations of new snow but somewhere around 20 cm is a good estimate for the region. This storm snow continues to build over a variety of old surfaces including old hard and soft wind slabs, scoured slopes, blue ice, thin melt-freeze crusts on southerly slopes and surface hoar. Many windward slopes are scoured and thin. Recent snowpack tests recently gave generally hard to no results near Smithers. An otherwise strong mid-pack overlies a weak base layer of facets/depth hoar. Triggering of this basal weakness may still be possible from thin spots and/or rocky outcrops. I suggest digging down, or probing the snowpack to get a handle of average snowpack depths, variability and test results. The average  snowpack depth is around 100 cm at treeline, but remains quite inconsistent across the region.

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