Bulletin d’avalanche

South Rockies

Jan 18 – 19, 2022Avalanche Canada
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Archivé · expiré 5 years ago

Danger d’avalanche

Thu
Fri
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Points saillants

The return of cold temperatures will bring fresh snow ! Be mindful of developing winds slabs throughout the day. 

Problèmes avalancheux

  • Wind Slabs

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

    Fresh and soft slabs will likely develop on exposed slopes at higher elevations with the forecasted winds and snowfalls. Older and hard winds slabs can still be found, confined to shady alpine areas where dry snow was affected by the recent strong winds. While these slabs may be thin, they could be poorly bonded to the underlying snow, so be extra cautious in lee terrain and convex rolls.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    2–3.5

    A persistent slab problem formed by a crust down 80-150 cm has created a low likelihood, high consequence scenario that is difficult to forecast. There has been an increase of avalanche reports on this layer since the past weekend. Although the snowpack is slowly recovering from the last warm spell, it is uncertain how the recent warming/rain has affected the snowpack. In the meantime, avoid likely trigger spots such as steep, rocky slopes with a shallow or thin to thick snowpack. 

Confidence

Moderate - Forecast snowfall amounts are uncertain.

Weather Forecast

MONDAY NIGHT: Snow 5-10 cm, treeline low of -5 C, strong southwesterly wind, freezing level lowering to valley bottom.

TUESDAY: Snow, 5-10 cm, treeline high around -8 C, moderate west wind, freezing level at valley bottom.

WEDNESDAY: Sunny periods, treeline high around -12 C, light northwest wind, freezing level at valley bottom.

THURSDAY: Flurries, treeline high around -5 C, strong southwesterly wind, freezing level rising to 1500 m.

Avalanche Summary

No new avalanches were observed nor reported in the last 24 hours.

On Thursday, three very large avalanches were reported from this region. These avalanches failed on the early December crust and showed wide propagation. They occurred on southwest to southeast aspects and were naturally triggered in response to rising temperatures and solar radiation.

The broader area including the South Rockies and neighbouring regions has been experiencing a sporadic pattern of very large avalanches over the last couple of weeks.

Snowpack Summary

Refreeze has created a melt-freeze crust up to 2000 m capping the recent snow which is settling fast and becoming dense due to warm temperatures. This snow sits on a variety of old surfaces, including soft snow in sheltered areas and wind slabs in exposed and open areas which formed over the past few days. Dry snow can still be found in the alpine but will likely be found as hard pockets of wind slabs.

The most notable layer of concern in the snowpack is a crust that was formed in early December and is now typically down 80-150 cm. In the neighbouring Lizard-Flathead region, three very large avalanches were reported on this layer on Jan 13. This layer has created a tricky low likelihood, high consequence scenario which is best managed through conservative terrain choices and disciplined backcountry travel techniques.

Terrain and Travel

  • Fresh wind slabs will likely form throughout the day, diligently watch for changing conditions.
  • Wind slabs may be poorly bonded to the underlying crust.
  • Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
  • Be aware of the potential for large avalanches due to the presence of a persistent slab.

Régions couvertes