Bollettino valanghe

Northwest Coastal

Feb 27 – 28, 2013Avalanche Canada
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Archiviato · scaduto 14 years ago

Pericolo valanghe

Fri
Sat
Alta quota
4 · Forte
Limite del bosco
4 · Forte
Sotto il limite
3 · Marcato

In sintesi

Problemi valanghivi

  • Storm Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely - Very Likely
    Dimensione
    1–5
    Snow, wind and rain (below treeline) are likely to cause a touchy storm slab problem in many areas.

Confidence

Fair - Timing, track, or intensity of incoming weather is uncertain for the entire period

Weather Forecast

Wednesday night/Thursday: Moderate to heavy snow (falling as rain for a time below about 900 m). Moderate to extreme SW winds. Freezing level 500 m, rising for a time to about 900m.Friday: Light snow. Moderate to strong S winds. Freezing level around 700m.Saturday: Light snow. Light winds. Freezing level dropping to valley floor.

Avalanche Summary

A few size 1 soft slabs were triggered by skiers at treeline on Tuesday.

Snowpack Summary

Strong winds created new wind slabs on a variety of slope aspects at treeline and above on Tuesday. Small surface hoar was also buried by 10-25 cm new snow. Further snowfall and wind will add to existing storm slab and wind slab problems. A rise in freezing level (aka rain) could rapidly weaken the snowpack below treeline.Old wind slabs are now buried on slopes lee to previous SW winds. Deeper in the upper snowpack, a crust, hard slab, and/or surface hoar interface exists, depending on aspect and elevation. One recent snowpack test near Shames resulted in a hard "pops" shear on the buried surface hoar, down around 60 cm at the time. Large cornices loom as a threat: they could act as triggers for avalanches on slopes below. Mid and lower snowpack layers are generally well settled and strong. The exception seems to be the Bear Pass area where basal facets are still reported.

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