Avalanche Forecast

Issued: Dec 3rd, 2022 4:00PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is moderate. Known problems include Persistent Slabs and Wind Slabs.

dsaly, Avalanche Canada

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

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.

Summary

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

A layer of surface hoar and crust is found 50-90 cm deep in the snowpack. Limited slab properties have developed, yet recent whumpfing and cracking suggest this layer is primed for human triggers. Reports indicate this layer of surface hoar is most prevalent above 1700 m and disappears above 2200 m, however at upper elevations a crust may also provide a weak bond.

Keep an eye on the wind or rising temperatures, slabs may quickly form wherever the fresh snow is encouraged to bond; and with a weak layer of surface hoar below, slabs may be more widespread, extend into treeline elevations, and be more reactive than expected in sheltered areas.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1.5 - 2.5

Wind Slabs

Southerly winds have impacted snow at upper elevations, incoming northwest winds may reverse-load features. There's a lot of loose snow out there, expect fresh slabs to form where the wind picks up.

Aspects: North, North East, East, South East, South, North West.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 1.5

Valid until: Dec 4th, 2022 4:00PM