Bulletin d’avalanche

South Rockies

Apr 12 – 13, 2012Avalanche Canada
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Archivé · expiré 14 years ago

Danger d’avalanche

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

Confidence is poor due to disagreeing weather models, track and timing. The region may receive heavier amounts of precipitation than forecast. If this occurs, expect the danger ratings to be elevated.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–4
    Forecast new snow above 1700 m, and moderate Southerly winds may create the perfect a recipe for building wind slabs on lee slopes, and behind terrain features at upper elevations.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely
    Taille
    2–6
    The odd deep slab could still be out there, I'm still suspect of steeper unsupported slopes and places where the snowpack goes from thick to thin, especially near ridge crest and around rock outcroppings.

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–5
    Continued light-moderate amounts of precipitation up to 1700 m is expected to continue or Thursday. Watch for loose wet avalanches below treeline. They may entrain more mass and run farther than expected. Glide cracks could fail at any moment.

Confidence

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

Weather Forecast

A low pressure center is moving into Southern Alberta where it should remain stationary through to Friday. This low will continue to spread light- moderate amounts of precipitation to the region through to later Saturday. Freezing levels on Friday are expected to rise to 2000 m. Through the weekend freezing levels will generally stay near 1900 m, rising to 2000 m by Monday. Solar radiation will be intense when the sun shines through. Ridgetop winds will be light-moderate from the SW-W.

Avalanche Summary

No new avalanche observation reported.

Snowpack Summary

On Thursday, up to 10 cm of new snow fell at upper elevations. With forecast snow and wind, wind slabs are likely building at higher elevations behind ridgecrests and terrain features. Lower elevations continue to see rain, and loose wet avalanches are likely. This recent spring- like warm weather has promoted settlement within the snowpack. Melt-freeze conditions exist, and snow is moist below 1700 m on all aspects. On solar aspects the snow has become moist to ridgetop and new snow may have a poor bond to the crust. Below the surface, down 60-100 cm sits on the March 27th interface which seems to be more predominant on southerly aspects. The bond on this interface seems to be improving, as field tests have shown no significant results. On Tuesday our field team went back to the Flathead to gather some observations. They found the mid Feb surface hoar layer down 280 cm, test results showed a Deep Tap Test of 21 with a sudden collapse characteristic. This layer currently sits dormant, but may wake up later this spring under a prolonged heat up. Glide cracks are a concern with the forecast rain below 1500 m. Be sure to give them a wide berth as they are very sensitive and could fail at any moment.

Régions couvertes