Bulletin d’avalanche

South Coast

Mar 6 – 7, 2014Avalanche Canada
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Archivé · expiré 13 years ago

Danger d’avalanche

Sat
Sun
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
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Points saillants

Friday should see a short lull in the weather before another strong Pacific frontal system delivers heavy snow, crankin' winds, and mild temperatures.

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    2–5
    This problem is a greater concern in northern sections where it is buried around 100 cm deep. New loading from snow and wind, or a smaller avalanche could be enough to wake this layer up and produce a very large avalanche.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    2–5
    Around 50-100 cm of dense storm snow sits on a weak melt-freeze crust buried at the beginning of March. Triggering is most likely in steep, wind-loaded north through east facing terrain at and above treeline.

Confidence

Fair

Weather Forecast

Friday: Mainly cloudy with flurries – around 5 cm. The freezing level is around 1200-1500 m and ridgetop winds are moderate from the W-NW.  Saturday: Moderate precipitation – 15-30 cm. The freezing level climbs to 1700 m and winds are very strong from the SW. Sunday: Continued moderate or locally heavy precipitation. The freezing level hovers around 1800 m and winds moderate and gusty from the SW.

Avalanche Summary

A fairly widespread natural avalanche cycle may have occurred on Thursday in response to new snow, strong alpine winds, and mild temperatures. Natural activity should taper off on Friday as conditions dry out briefly, but rider triggering remains a concern. Warm temperatures and light rain to ridge top produced a fairly large natural avalanche cycle near the Coquihalla on Wednesday. Numerous slab avalanches up to size 3 were reported, likely failing on the early March melt-freeze crust. Just to the south, in Allison Pass, a spike in temperatures and periods of sunshine triggered loose wet avalanches up to size 2.

Snowpack Summary

Coquihalla and south: Strong southerly winds have redistributed some of the new snow and formed thick wind slabs in exposed lee and cross-loaded terrain. Up to 100 cm of storm snow has fallen in the past few days. This new snow may feel upside down due to warming temperatures, and appears to be bonding poorly to the early March melt-freeze crust. The mid February weak layer of crusts and facets, now down over 200 cm deep, has been reported to be rounding and bonding. Duffey Lake and north: New dense wind slabs are likely in exposed NW-E facing terrain and cross-loaded features. The early March melt-freeze crust is down 40-60 cm everywhere except high north aspects. The mid Feb weak layer is generally down 70-120 cm depending on orientation to wind. Recent snowpack tests continue to give pops shears where this layer is less than 100 cm deep. Deeply buried weak layers of facets and depth hoar remain a concern on high alpine slopes with thin or variable snow cover.

Régions couvertes