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Avalanche Forecast

Archived

Dec 3rd, 2022–Dec 4th, 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 avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

North Columbia, South Columbia, Blue River, Clearwater, Clemina, Esplanade, Jordan, North Monashee, North Selkirk, West Purcell, Badshot-Battle, Central Selkirk, Goat, Gold, Kokanee, Retallack, Valhalla, Whatshan.

Tricky-Moderate: A weak layer of surface hoar continues to whumpf and crack. Choose conservative terrain and consider that hazard may be highest at treeline elevations.

Confidence

Low

Avalanche Summary

On Wednesday, a natural avalanche cycle size 2-3 was reported in both the Selkirks and Monashees north of Revelstoke. Whumpfing and cracking were reported throughout the region.

On Thursday, skiers remote triggered a size 2 on surface hoar at treeline in the Selkirks south of Revelstoke. Throughout the region, widespread whumpfing and cracking continued to be reported.

A weak layer of surface hoar below recent snow has been responsible for recent instability. Reports suggest this interface is most prevalent at treeline, between 1700-2000 m.

Snowpack Summary

20-30 cm recent snow remains low density in most areas with wind effect at upper-treeline and higher. Now buried 40-80 cm, a layer of surface hoar, crust, and faceted crystals is the primary concern of persistence and has been the key component of a past natural avalanche cycle. This layer has been most reactive between 1700-2200 m. Snowpack depths range from 70 cm at treeline to 150 cm in the alpine, with wind-loaded areas exceeding 200 cm.

Weather Summary

Saturday night

Cold, valley cloud forming overnight. Light north wind up to 20 km/hr. Treeline temperature low -22 C.

Sunday

Cold, valley cloud burning off in the morning. North wind 5-15 km/hr. Treeline high temperature -12 C.

Monday

Increasing cloud and isolated flurries, trace accumulation. West wind 15-25 km/hr. Treeline high temperature -15 C.

Tuesday

Increasing wind and flurries, trace to 5 cm. Southwest wind 15-30 km/hr. Treeline temperature rising to -9 C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
  • Keep in mind that human triggering potential persists as natural avalanching tapers off.
  • Carefully monitor the bond between the new snow and old surface.

Problems

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.

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.