Bulletin d’avalanche

Yukon

Jan 11 – 12, 2022Avalanche Canada
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Archivé · expiré 5 years ago

Danger d’avalanche

Thu
Fri
Alpin
3 · Marqué
Limite forestière
2 · Modéré
Sous la limite
Sans niveau
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Points saillants

Wind continues to be the main driver of the avalanche danger and new wind slabs are likely touchy in exposed terrain. Recent observations have been very limited and older wind slabs overlying facets from last week's outflow wind event may still be reactive. 

Problèmes avalancheux

  • Wind Slabs

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

    Ongoing snowfall and strong southerly winds continue to build new reactive wind slabs in exposed terrain. These slabs likely overlie a weak interface and may remain reactive longer than normal. 

    Older hard slabs exist on all aspects from last week's northerly outflow winds. These slabs overlie a widespread weak layer of facets and may still be reactive to human triggers in steep, unsupported terrain. Until more information becomes available, reactive wind slabs should be expected on all aspects. 

Confidence

Low - Uncertainty is due to the limited number of field observations.

Weather Forecast

A low pressure system is expected to slide down the coast bringing light snowfall to the region Monday night and Tuesday. The weather models are currently showing variability regarding the timing and amounts of snowfall. 

Monday Overnight: Snowfall 5-15 cm, moderate to strong S wind, treeline temperature around -8 °C.

Tuesday: Periods of snowfall 5-10 cm, strong S-SW wind, treeline high around -6 °C.

Wednesday: A mix of sun and cloud, light to moderate SW wind, treeline high around -8 °C.

Thursday: Snowfall 5-10 cm, strong S wind, treeline high around -6 °C.

Avalanche Summary

No new avalanches have been reported recently but observations have been very limited due to the cold conditions. If you are out in the mountains, please consider posting your observations to the MIN. 

Last week, a natural avalanche cycle occurred in White Pass. This was a result of sustained north winds redistributing the 30-40 cm of storm snow from New Year's Eve. This MIN from last Wednesday describes widespread size 2 avalanches, running well into treeline. 

Snowpack Summary

20-40 cm of recent storm snow plus the ongoing new snowfall will continue to be redistributed by strong southerly winds into fresh wind slabs in exposed terrain. These new wind slabs overlie a heavily wind-affected and faceted snow surface. The new snow will likely bond poorly to the old snow surfaces and newly formed wind slabs may remain reactive to human triggering for longer than normal. Reports from the Avalanche Canada field team include scouring to ground in exposed terrain, particular on north through east aspects. The height of snow is reported to be extremely variable. Older wind slabs from the outflow wind event last week may still be reactive and wind slabs should be expected on all aspects until more information becomes available. 

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • In times of uncertainty conservative terrain choices are our best defense.
  • Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.

Régions couvertes