Avalanche Forecast

Issued: Dec 18th, 2018 4:51PM

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

Avalanche Canada dsaly, Avalanche Canada

Natural avalanche activity has tapered off, however the chance for human triggered avalanches remains likely.

Summary

Confidence

Moderate -

Weather Forecast

TUESDAY NIGHT: Cloudy with isolated flurries, up to 5 cm new snow. Alpine temperatures below -7C, freezing level below 1000 m. Moderate southwest wind.WEDNESDAY: Cloudy with flurries, accumulating 5-10 cm new snow. Moderate southwest wind. Freezing level around 1200 m. THURSDAY: Snow increasing through the day, accumulating 20-30 cm. Strong southwest wind. Freezing level around 1200 m.  FRIDAY: Cloudy with isolated flurries, accumulating up to 5 cm. Moderate west wind with strong gusts. Freezing level below 1000m.

Avalanche Summary

There were reports of natural and human triggered avalanches to size 2.5 and explosives triggered avalanches to size 3 on Saturday.A notable human triggered size 2.5 avalanche was reported in Allan Creek on Saturday. The avalanche was triggered on a northeast facing slope in the alpine. A report of this avalanche can be found on the Mountain Information Network. (here)Numerous natural and explosives triggered avalanches to size 3, and human triggered avalanches to size 2.5 were reported everyday in the region from Wednesday December 12 to Saturday December 15. Many of these have been remote triggered (triggered from a distance). Natural avalanche activity appears to have subsided, but human-triggered avalanches remain likely.A size 4 natural avalanche was reported to have run full path, burying a road on the west side of Kinbasket Lake. This avalanche occurred in the North Columbia region, but it is a significant event and is very close to the boundary between the North Columbia and Cariboo regions. These full path avalanches can catch people by surprise, especially when there is little to no snow in the valley bottoms. A report of this avalanche can be found on the MIN here

Snowpack Summary

Up to 30 cm very recent snow brings storm totals to 60-120 cm over the last week or so. This new snow sits on a weak layer that consists of facets (sugary snow), surface hoar (feathery crystals), and a sun crust (on south aspects). Strong winds have promoted widespread slab formation, particularly with the most recent new snow available for transport.A weak layer from mid November is now buried up to 150 cm and consists of surface hoar in shady locations, and a sun crust on steep south facing slopes. The potential may exist for smaller avalanches to step down and trigger this deeper layer, resulting in very large avalanches. The most likely place for this layer to be a problem is on steep, south facing slopes at treeline where the surface hoar sits on the sun crust.At the base of the snowpack is a crust that formed in late October. The probability of triggering this layer is low, but the most suspect areas would be large, steep, rocky alpine features with a shallow snowpack. It would likely take a large trigger such as a cornice fall to produce an avalanche on this layer.

Problems

Persistent Slabs

An icon showing Persistent Slabs
Up to 120cm of new snow sits on a weak layer of facets (sugary snow), surface hoar (feathery crystals), and sun crust. Wind loaded pockets could have 200+ cm over this layer.
Avalanches on this layer may step down to deeper layers resulting in very large avalanches.Use conservative route selection, choose moderate angled and supported terrain with low consequence.Be careful with wind loaded features like cross-loaded gullies, steep rolls, and near cornices.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 3

Wind Slabs

An icon showing Wind Slabs
Recent new snow and wind have set up wind slabs on lee (downwind) slopes in exposed areas
Watch for whumpfing, hollow sounds, and shooting cracks.Use caution in lee areas. Recent wind has created wind slabs.Avoid steep lee and cross-loaded slopes

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1.5 - 2

Valid until: Dec 19th, 2018 2:00PM

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