Bulletin d’avalanche

Banff Yoho Kootenay

Mar 20 – 21, 2022
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Archivé · expiré 5 years ago

Danger d’avalanche

Tue
Wed
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré

Points saillants

We have a lot of uncertainty about the sensitivity and distribution of the current windslab problem. Observations from the high alpine are limited, but given our observations of drifting snow at ridge crests, we're concerned about windslab formation.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–2

    Sunday was windy and we observed much wind effect across the snowpack on open slopes at treeline and especially in the high alpine. These slabs will be quite sensitive initially before they begin to bond.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    1.5–3

    Buried crust/facet layers exist in the upper snowpack on solar aspects and all aspects below 1700m. Recent tests show moderate sudden planar results. Exercise caution in areas where these crusts exist, there is uncertainty about how they will react.

Weather Forecast

A weak ridge over the area gives clearing skies overnight Sunday, but on Monday we switch to a SW flow (storm track) and clouds move into the area. No precipitation is expected and light winds; a similar day as was Sunday. Tuesday expect a RAPID warm-up and strong SW winds with FL's exceeding 2000m for Wednesday and snow/rain on the way.

Snowpack Summary

20-50 cm of storm snow forming fresh wind slabs in alpine and some treeline terrain with mod-strong SW winds. On solar aspects a variety of buried sun-crusts down 30-60 cm are producing moderate results in tests. In addition there is a buried temperature crust at lower elevations that exists on all aspects, and has been reactive in Kootenay Park.

Avalanche Summary

No new activity reported Sunday. Explosive control in Kootenay Park on Thursday produced unexpectedly large avalanches at low elevations. On Sunday, Bourgeau-Left waterfall (next to Sunshine gondola) released a large natural avalanche that ran over the waterfall and hit Healy Creek. This may have been triggered by a cornice or strong solar effect.

Confidence

Régions couvertes