Avalanche Forecast

Issued: Dec 17th, 2018 3:53PM

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

Avalanche Canada jfloyer, Avalanche Canada

Another storm on Monday night/Tuesday will keep avalanche danger elevated.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain

Weather Forecast

MONDAY NIGHT: 5-15 cm new snow expected. Strong southwesterly winds.TUESDAY: 10-15 cm additional new snow with freezing levels around 1400 m. Strong southwesterly winds.WEDNESDAY: 4-8 cm new snow. Freezing levels around 1300 m. Moderate westerly winds.THURSDAY: 5-10 cm new snow, increasing through the day. Freezing level around 1000 m. Moderate southeasterly winds.

Avalanche Summary

Avalanche activity continues in the North Columbia region with natural and explosives triggered avalanches to size 3.5, as well as human triggered avalanches to size 2 being reported on Saturday and Sunday.Numerous natural and explosives triggered avalanches to size 3.5 and human triggered avalanches to size 2.5 have been reported in the region every day since Wednesday, December 12. Many of these avalanches were triggered from a distance (remote triggered).

Snowpack Summary

70-130 cm of recent storm snow sits on a weak layer of facets (sugary snow), surface hoar (feathery crystals), and a sun crust (on south facing slopes). Strong winds have promoted widespread slab formation.A weak layer from mid November is now buried up to 150 cm and consists of surface hoar and a sun crust. 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. Concern for this layer is dwindling but it may still be worth considering in places such as steep, rocky, alpine terrain, especially where the snowpack is shallow. 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 90 cm of new snow sits on a weak layer of facets (sugary snow) surface hoar (feathery crystals) and sun crust (on south facing slopes). Wind loaded pockets could have 200+ cm of snow over this layer.
Avalanches on this layer may step down to deeper layers resulting in very large avalanches.Remote triggering is a concern, watch out for adjacent slopes.Use conservative route selection, choose low angle and supported terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1.5 - 3.5

Storm Slabs

An icon showing Storm Slabs
New snow and strong winds will have built storm and wind slabs particularly on lee (downwind) slopes in exposed areas.
Avoid avalanche terrain during periods of heavy loading from new snow and wind.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

1 - 2.5

Valid until: Dec 18th, 2018 2:00PM

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