Bulletin d’avalanche

North Rockies

Feb 5 – 6, 2022Avalanche Canada
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Danger d’avalanche

Mon
Tue
Alpin
4 · Fort
Limite forestière
4 · Fort
Sous la limite
4 · Fort
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Points saillants

Human triggering of large avalanches will remain very likely on Saturday. Danger may be a step less for the north and far east of the region, but use extra caution if you find more than 15 cm of new snow.

Problèmes avalancheux

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely - Very Likely
    Taille
    1.5–2.5

    Storm totals may reach somewhere around 40 to 60 cm by the end of Saturday. Wind slabs will be found in lee terrain features at higher elevations from strong southwest wind. Storm slabs are found in sheltered terrain. These slabs will be particularly touchy where they are loading a weak layer of surface hoar crystals, which is most likely found in openings at and below treeline. Large, wide-propagating avalanches could result where this layer is present.

Confidence

High - We are confident the likelihood of avalanche will increase with the arrival of the forecast weather.

Weather Forecast

FRIDAY NIGHT: Cloudy with snowfall, accumulation 10 to 20 cm with the most in the southwest of the region, 60 to 80 km/h west wind, alpine temperature -6 C, freezing level 1000 m.

SATURDAY: Early-morning snowfall then clearing, accumulation 2 to 5 cm, 50 km/h west wind, alpine temperature -6 C, freezing level 1000 m.

SUNDAY: Mix of sun and cloud with intermittent snowfall, accumulation 2 to 5 cm, 60 km/h southwest wind, alpine temperature -4 C, freezing level 1500 m.

MONDAY: Cloudy with snowfall, accumulation 10 to 20 cm, 60 km/h southwest wind, alpine temperature -5 C, freezing level 1400 m.

Avalanche Summary

We haven't received any reports from Friday but suspect that both natural and rider-triggered avalanches occurred during the stormy weather. Large avalanches are expected in areas where the buried surface hoar described in the Snowpack Summary exists. 

Looking towards Saturday, avoidance of consequential avalanche terrain is your best bet for having a safe day. Storm and wind slabs will be very touchy due to all the recent snow and wind. Rain at low elevations will also quickly destabilize the storm snow. The snow will need time to stabilize.

Snowpack Summary

Storm totals will reach 40 to 60 cm by the end of Saturday for much of the region, with the most in the southwest of the region and the least to the east of the divide and in the north. The snow has likely formed storm slabs in sheltered areas and wind slabs in lee terrain features from strong southwest wind. These slabs will remain touchy for the remainder of the weekend as the freezing level rises and the air gets warmer.

The snow will be particularly touchy where it sits on a weak layer of surface hoar crystals. Reports suggest that the surface hoar is likely most prominent in sheltered openings at and below treeline but could extend into wind-sheltered terrain in the alpine. Example terrain features to treat as suspect include the lee side of protected ridges, openings in the trees, cut blocks, and burns.

The lower snowpack is generally strong and well-bonded. The base of the snowpack is expected to be weak and faceted in shallow, rocky slopes east of the divide.

Terrain and Travel

  • Travel in alpine terrain is not recommended.
  • Avoid all avalanche terrain during periods of heavy loading from new snow and wind.
  • Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
  • Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.

Régions couvertes