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Avalanche Forecast

Archived

Feb 2nd, 2022–Feb 3rd, 2022

Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural and human triggered avalanches likely.
Treeline
Natural and human triggered avalanches likely.
Below Treeline
Natural avalanches possible, human triggered probable.
Alpine
Natural and human triggered avalanches likely.
Treeline
Natural and human triggered avalanches likely.
Below Treeline
Natural avalanches possible, human triggered probable.

Regions

North Rockies.

Be wary of wind slabs in steep terrain features. Also note that recent snow may sit on a weak layer at lower elevations.

Confidence

Moderate - Uncertainty is due to how quickly the snowpack will recover and gain strength.

Weather Forecast

WEDNESDAY NIGHT: Cloudy with snowfall, accumulation 2 to 5 cm, 40 km/h northwest wind, alpine temperature -14 C.

THURSDAY: Cloudy with snowfall, accumulation 5 cm, 40 km/h west wind, alpine temperature -14 C.

FRIDAY: Cloudy with snowfall, accumulation 20 to 40 cm, 60 to 80 km/h southwest wind, alpine temperature -5 C.

SATURDAY: Early-morning snowfall then clearing, accumulation 10 to 20 cm, 60 to 80 km/h west wind, alpine temperature -6 C, freezing level 1300 m.

Avalanche Summary

The recent snow has been most reactive as either wind slabs in exposed terrain at higher elevations or as loose dry avalanches in sheltered terrain. Most avalanches were small and found on all aspects.

Looking forward to the coming days, wind slabs may remain touchy to riders. Slabs at and below treeline are expected to become touchy once the snow settles and forms a cohesive slab and where it sits on the surface hoar described in the snowpack summary. This may occur with an upcoming storm forecast for Friday and into the weekend.

Snowpack Summary

Around 15 to 30 cm of recent snow has been blown into wind slabs in terrain exposed to the wind at higher elevations. Wind slabs may be found on all aspects due to variable wind directions. In sheltered terrain, the snow may sit above a weak layer of surface hoar crystals. So far, reports suggest that the snow hasn't formed slab properties, except where it has been affected by wind. We've received indication that the surface hoar is likely most prominent in sheltered openings at and below treeline but could extend into the alpine. Example terrain features include the lee side of protected ridges, openings in the trees, cut blocks, and burns. The snow may sit on a hard melt-freeze crust on steep sun-exposed slopes.

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

  • Carefully evaluate steep lines for wind slabs.
  • Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
  • Watch for signs of slab formation throughout the day.
  • Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.

Problems

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.