Bulletin d’avalanche

Banff Yoho Kootenay

Mar 15 – 16, 2019Parks Canada
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Archivé · expiré 8 years ago

Danger d’avalanche

Sun
Mon
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Points saillants

After the wind and later the sun triggered many avalanches today, cloudy skies and light winds are expected Saturday. Clearing Sunday however, marks the beginning of a significant warming trend that is expected to increase avalanche activity.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–2
    New snow and strong SW-W winds have built wind slabs in open areas above treeline. In some cases, these slabs sit over the weak faceted snow and have been sensitive to triggering. In may cases, these slabs initiate a loose dry avalanche as well.

  • Loose Dry

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2.5
    The faceted snow is easily initiated as a sluff in steep terrain that will entrain all available loose snow until it hits lower angled terrain. If a windslab or cornice initiates these, expect increased width, mass, momentum and reach.

Weather Forecast

After a few patches of clear sky late in the day Friday, a return to more clouds seems likely for Saturday as winds diminish and temps stay largely static. Clearing skies midday Sunday looks to mark the beginning of a significant warming trend that will bring freezing levels to 3000m later in the week. An increase in avalanche activity is expected.

Snowpack Summary

15- 40cm has accumulated since March 7. Modertate to strong SW-W winds have redistributed this snow treeline and above. This snow sits over previous widespread wind effect in the alpine, suncrusts on steep S aspects and 30-50cm of sugary facets everywhere else. While a tough midpack exists in thicker areas, facets to ground are seen in many others.

Avalanche Summary

Fresh snow overnight, with moderate to strong winds led to a cycle Friday morning with slabs to sz 2.5 and loose dry avalanches to sz 1.5. As has been seen over the last week: the loose dry avalanches often entrain significant amounts of old faceted snow in steep terrain and continue to run until they hit lower angle terrain.

Confidence

Timing or intensity of solar radiation is uncertain on Sunday

Régions couvertes