Bollettino valanghe

South Coast

Mar 13 – 14, 2017Avalanche Canada
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Archiviato · scaduto 10 years ago

Pericolo valanghe

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

In sintesi

Tuesday's danger hinges on the snow line. Rain is expected all the way to treeline, so you'll need to increase the rating by one step if you encounter more than 20 cm of new snow at treeline.

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely - Possible
    Dimensione
    2–4
    Storm snow from the past week sits over a buried persistent weak layer. Thick storm slabs in the alpine may have enough mass to step down to this layer while sustained rainfall may be enough to reawaken it at lower elevations.

  • Storm Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Very Likely
    Dimensione
    1–2
    Up to 60 cm of new snow over Monday night and Tuesday will form thick storm slabs on the surface in the alpine. These slabs will be primed for human triggering. Expect stability to deteriorate as you gain elevation and as snow continues to fall.

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible - Likely
    Dimensione
    1–2
    A natural loose wet avalanche cycle has already occurred, but up to 60 mm of rain in the forecast will sustain the potential for further loose wet avalanche activity at lower elevations on Tuesday.

Confidence

Moderate - Freezing levels are uncertain

Weather Forecast

Tuesday: Periods of rain and wet snow bringing around 60mm to lower elevations and 50-60 cm of new snow to high alpine elevations. Strong southwest winds. Freezing level to 1700 metres with alpine temperatures around 0 to -1. Wednesday: 15mm of rain below about 800 metres, with around 15 cm of new snow above. Moderate southwest winds. Freezing level to 1200 metres with alpine temperatures of -1. Thursday: Flurries bringing 10 cm of new snow. Moderate southwest winds. Freezing level to 900 metres with alpine temperatures of around -2.

Avalanche Summary

No new avalanches have been reported, but it should be noted that the warm, stormy weather has been discouraging some backcountry travel and obscuring visibility into alpine terrain.Looking forward, the primary hazard will exist where new snow is accumulating instead of rain. This will become increasingly relevant as you reach upper treeline elevations or if you are exposed to alpine slopes overhead. As rain continues to fall, ongoing potential also exists for loose wet avalanche activity, especially on steeper slopes. Ongoing rain and snow at higher elevations will also maintain the risk of large avalanches releasing over the late February interface. Large, open terrain features and avalanche paths should be avoided while this potential exists.

Snowpack Summary

Heavy rain has saturated the upper snowpack at all but high alpine elevations after roughly 50mm of precipitation fell over Sunday night and Monday morning. Any new snow that may have accumulated at high alpine elevations is likely to remain reactive to human triggering over the short term. At higher elevations, lingering potential may exist for loading from rain or snow to promote reactivity at the late February interface, roughly 1.5 metres deep. This layer is composed of a sun crust on southerly aspects and surface hoar on shaded aspects. An avalanche on this layer would be large and very destructive. No concerns exist below this interface and the snowpack at treeline and below is generally well settled and strong.

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