Bulletin d’avalanche

Purcells

Jan 1 – 2, 2022Avalanche Canada
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Archivé · expiré 5 years ago

Danger d’avalanche

Mon
Tue
Alpin
3 · Marqué
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré

Points saillants

Forecast snow and strong southwesterly winds on Sunday are expected to form fresh wind slabs on lee features at treeline and above.

 Watch for newly formed and reactive wind slabs as you transition into wind affected terrain. 

Problèmes avalancheux

  • Wind Slabs

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

    Forecast snow and strong southwesterly winds on Sunday are expected to form fresh wind slabs on lee features at treeline and above.

  • Persistent Slabs

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

    A persistent slab problem formed by a crust down 50-120 cm has created a low likelihood, high consequence scenario that is difficult to forecast.

    Avoid likely trigger spots such as steep, rocky slopes with a shallow or thin to thick snowpack.

Confidence

Moderate - Uncertainty is due to the timing, track, & intensity of the incoming weather system.

Weather Forecast

SATURDAY NIGHT: Cloudy with isolated flurries; 0-5 cm / Strong southwest wind / Low of -21

SUNDAY: Snow; 5-15 cm / Strong southwest wind / High of -14

MONDAY: Snow; 5-15 cm / Moderate southwest wind / High of -9

TUESDAY: Cloudy / Light west wind / High of -10

Avalanche Summary

No new avalanches were reported on Friday.

We've had consistent reports of persistent slab avalanches on reloaded bed surface crusts from the Invermere area this month. On Thursday, a size 1 was triggered remotely by bootpacking on a thin northeast aspect in the alpine. Explosive control work on December 26th produced large avalanches (size 2) on the crust found 40-70 cm deep.

Snowpack Summary

Forecast snow and strong southwesterly winds on Sunday are expected to form fresh wind slabs on lee features at treeline and above.

 A layer of weak surface hoar crystals may exist under the recent snow at treeline and below. 

 

The most notable layer of concern in the snowpack is a crust that was formed in early December and is now down 60-120 cm. Activity on this layer has been sporadic. It has generally been triggered on steep, rocky slopes, with a shallow or thin to thick snowpack.

This layer has created a low likelihood, high consequence scenario which is best managed through conservative terrain choices and disciplined backcountry travel techniques.

A late October facet/crust layer sits at the bottom of the snowpack above 1900m. 

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Fresh wind slabs will likely form throughout the day, diligently watch for changing conditions.
  • Seek out wind sheltered terrain below treeline where you can avoid wind slabs and find great riding.
  • Be aware of the potential for large avalanches due to the presence of a persistent slab.
  • Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.

Régions couvertes