Bulletin d’avalanche

Kootenay Boundary

Feb 29 – Mar 1, 2012Avalanche Canada
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Archivé · expiré 15 years ago

Danger d’avalanche

Fri
Sat
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
3 · Marqué
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Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    2–6
    The Feb 08 surface hoar/facet/crust combination is now buried by up to a meter of new snow. This snow has consolidated into a slab. Avalanches triggered on this layer will likely be large, destructive & potentially deadly.

  • Loose Dry

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely - Very Likely
    Taille
    1–3
    Wednesday afternoon's snow is falling on surface hoar/facets on shady slopes & a thin sun crust on solar aspects. This is a manageable avalanche problem with proper sluff mgmt. technique.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–4
    Storm slabs from the weekend continue to be sensitive to the weight of a skier or sledder. Storm slabs are capable of size 2 avalanches & they may step down and trigger the persistent slab avalanche.

Confidence

Good

Weather Forecast

THUR: A dirty ridge hangs over much of the region today bringing cloudy skies and the occasional convective flurry. I'm only expecting a few cm's Thursday, even in the most favored valleys. The atmosphere stabilizes Thursday evening & 2000m temps drop down to - 16 overnight. FRI: Friday dawns cool & cloudy, but, it is a day of change in the pattern. Freezing levels rise to 1000m as the ridge flattens late in the day. Snow should start up around supper time & but only 2 - 5 cm are expected to be on the ground when we wake up Saturday. SAT: Saturday offers occasional snow flurries with a daytime total of 5cm or so. Freezing level will continue to rise to 1500m. SUN: Precip should pick up in intensity Sunday, but the freezing level is forecast to be quite high, near 2000m, so most of the precip will fall as rain on everything but the highest peaks. 5mm of water is expected Sunday. The precip shuts down Monday and temps drop back down to seasonal norms. 2000m Wind: Thur: L, NWFri: W, Mod, G StrongSat: W, StrongSun: Strong W, switching Strong SW midday.

Avalanche Summary

The majority of the activity yesterday was in the form of loose snow avalanches to size 1.5 in steep, open terrain. Two size 2 - 2.5 avalanches were reported in the Bonnington range, on E & W aspects, both were remote triggered, failing on the Feb. 08 SH.

Snowpack Summary

5 cm of snow has fallen as of 3:00pm Wednesday. This new snow is falling on surface hoar on shady aspects and a thin sun crust on solar aspects which will keep the sluffing problem alive in steep open terrain. The big story continues to be the buried surface hoar, now down 60 - 120 cm below the snow surface. Avalanche activity on this layer has slowed a bit, but it is still producing. When it goes, it goes big. This layer is growing more stubborn, but it is still more than capable of producing avalanches to size 3 which by definition are big enough to destroy a car or woodframe house. Professionals throughout the region are treating this layer with extreme caution, since it is showing signs of remote triggering and the ability to propagate in low angled terrain. In the alpine there may be enough wind to create new windslabs that are softer and probably will not bond well to the old surface.

Régions couvertes