Bulletin d’avalanche

North Rockies

Mar 6 – 7, 2023Avalanche Canada
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Archivé · expiré 4 years ago

Danger d’avalanche

Wed
Thu
Alpin
3 · Marqué
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Points saillants

Wind slab are the main concern. Avoid wind-loaded features and steer well clear of overhead cornices and sun-affected slopes during periods of strong solar radiation. The best and safest riding will be found in sheltered locations.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–2.5

    Last week's snow fell with moderate to strong southwest winds, which recently switched to the northeast. Wind slabs will exist on a variety of aspects in the alpine and exposed areas at treeline and riders should be cautious of the reverse loading pattern with the recent northerly winds.

    Avoid sun-affected slopes in areas that see clear skies and strong sun. Surface snow may rapidly lose cohesion.

  • Cornices

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    2–3

    Minimize your exposure to cornices, they have grown significantly in recent weeks and can trigger large avalanches on the slopes below. Give them respect and a wide birth when you are travelling under them. Be cautious of solar input.

Confidence

Moderate

Avalanche Summary

Last week, southwest winds redistributed storm snow and several natural and human-triggered wind slabs were observed in the alpine and treeline primarily on north facing slopes.

As winds shifted to the northeast on Saturday, fresh wind-slab development was noted on more typically wind-scoured south to west slopes. These fresh slabs were reactive to sled traffic, check out this MIN from Pine Pass for details.

Check out our Field Team's MIN from Kakwa last week, where they found excellent riding in sheltered areas but reactive storm and wind slabs in open and exposed areas.

Looking forward to Monday, wind slabs continue to be the main concern. Wind slabs may exist on all aspects in exposed areas and riders should seek out sheltered terrain for the best and safest riding.

Deep persistent avalanches were also reported in nearby regions, mainly south of Valemount in the Rockies. This layer is present in this region, but has not produced recent activity.

Snowpack Summary

Variable winds have redistributed storm snow into deeper deposits on many aspects while soft snow remains in sheltered areas. Storm totals overlie heavily wind effected snow now roughly 20-60 cm deep. This interface remains slow to bond and gain strength.

The middle of the snowpack is generally strong.

A weak layer of large and weak facets is found near the base of the snowpack. This layer is present in this region, but currently considered 'dormant' as it has not produced recent activity. Backcountry users should continue to avoid thin and rocky start zones where triggering a deep persistent avalanche would be most likely.

Weather Summary

Sunday night

Clear periods. Alpine temperatures drop to a low of -15 °C. Ridge wind southeast 15 km/h. Freezing level at valley bottom.

Monday

Sunny with cloudy periods and isolated flurries. Alpine temperatures reach a high of -8 °C. Ridge wind south 10-25 km/h. Freezing level at valley bottom.

Tuesday

Sunny with cloudy periods. Alpine temperatures reach a high of -4 °C. Ridge wind south 25-45 km/h. Freezing level at valley bottom.

Wednesday

Sunny. Alpine temperatures reach a high of -4 °C. Ridge wind southeast 25-45 km/h. Freezing level 700 meters.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Recent wind has varied in direction so watch for wind slabs on all aspects.
  • Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
  • Minimize exposure to sun-exposed slopes when the solar radiation is strong.
  • Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.

Régions couvertes