Bollettino valanghe

South Columbia

Mar 25 – 26, 2015Avalanche Canada
Vedi sulla mappa
Archiviato · scaduto 12 years ago

Pericolo valanghe

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

In sintesi

A complex and unpredictable snowpack exists, especially in the northern half of this region. Avalanche danger will rise with rapid warming, precipitation and strong winds.

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible - Likely
    Dimensione
    3–5
    A persistent weak layer is buried anywhere from 40-80 cm below the surface and has produced numerous large avalanches recently. Storm slab avalanches could easily step down to this layer and remote triggering is possible.

  • Storm Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible - Likely
    Dimensione
    1–4
    Storm slabs up to 60 cm thick may overlie a weak layer and remain reactive to human-triggering. These slabs may be moist or wet at lower elevations.

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible - Likely
    Dimensione
    1–3
    Rising freezing levels and an extended period of warm temperatures will likely deteriorate the upper snowpack, resulting in loose wet avalanche activity.

Confidence

Fair - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

A Pacific frontal system reaches the coast today and affects the Interior regions tonight through the forecast period. Warm air aloft will invade the region until Friday night with associated freezing levels near 2800 m. A trailing cold front will bring light precipitations and strong ridgetop winds. On Thursday, light precipitation amounts up to 3-10 mm is expected, ridgetop winds strong from the SW and freezing levels rising to 2700 m. On Friday, solar radiation may come into play with a mix of sun, cloud and freezing levels steady at 2800 m. Unsettled conditions on Saturday will bring light precipitation amounts 2-10 mm, ridgetop winds moderate from the NW and freezing levels dropping to 1500 m.

Avalanche Summary

On Tuesday, numerous natural solar induced slab avalanches were reported, with the majority being size 1. We also received numerous reports of human triggered slab avalanches up to size 2, mostly running on N-NE aspects and above 2000 m. Explosive controlled avalanches were also initiated up to size 3. Most of these avalanches from Tuesday failed within the recent storm interface and on the mid-March persistent interface. With a warm, wet and windy storm in the forecast natural and human triggered avalanche activity will likely continue. Avalanches that fail on the deeper weak interfaces will be large and destructive.

Snowpack Summary

At higher elevations, 40-60 cm of dense storm snow sits over the mid-March interface which included crusts, wind affected surfaces, and/or old wind slabs. This interface has recently come alive and has been reactive, especially in the North (Revelstoke and surrounding area). Snow-pit testing varies regionally, with this interface generally showing moderate to hard results with a resistent-sudden planar fracture characteristic. Recent snowfall amounts taper off towards the south of the region. Strong SW winds had redistributed the new snow into wind slabs on leeward features. Digging deeper, 50-80 cm is the mid-February facet/crust interface. There is some concern for this layer to wake-up in the South Columbia region and storm slab avalanches have the potential to step down to it. Snow surfaces are wet to around 1700 m and moist to around 2200 m.

Regioni coperte