Avalanche Forecast

Issued: Dec 18th, 2018 4:37PM

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

Avalanche Canada dsaly, Avalanche Canada

Slab development continues with more snow and wind. Choose conservative terrain as the new snow redistributes and settles.

Summary

Confidence

Moderate -

Weather Forecast

TUESDAY NIGHT: Flurries, accumulating up to 10 cm. Moderate west wind. Freezing level below 1000 m. WEDNESDAY: Flurries, accumulating up to 10 cm. Moderate southwest wind. Freezing level 1300 mTHURSDAY: Snow, 15-25 cm new snow, increasing through the day. Moderate southwest wind with strong gusts. Freezing level 1300 m. FRIDAY: Cloud and isolated flurries, up to 5 cm snow. Light to moderate west wind. Freezing level valley bottom.

Avalanche Summary

Numerous natural and explosives triggered avalanches to size 3.5 and human triggered avalanches to size 2 have been reported in the region daily since Wednesday, December 12. Many of these avalanches were triggered from a distance (remote triggered) and two remote triggered avalanches (size 1.5-2) were reported on Monday.A skier was caught in an avalanche on Sunday on a west aspect at around 2000 m on a small slope, which released at a depth of 50 cm on buried surface hoar.

Snowpack Summary

Approximately 70-120 cm of recent storm snow sits on a weak layer of facets (sugary snow), surface hoar (feathery crystals) and a sun crust (on south aspects). Strong to extreme winds have promoted widespread slab formation.Another weak layer of surface hoar and sun crust that formed in mid November is up to 120 cm below the surface. This layer is most likely to be a problem in areas where the surface hoar sits on the sun crust. This combination is most likely found on steep, south facing slopes at treeline. The potential may exist for smaller avalanches to step down and trigger this deeper layer, resulting in large avalanches.At the base of the snowpack is a crust that formed near the end of 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 120 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
Remote triggering is a concern, watch out for adjacent slopes.Use conservative route selection, choose low angled terrain with low consequence.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 3

Storm Slabs

An icon showing Storm Slabs
Storm and wind slabs are likely to form on steep slopes in lee (downwind) areas. The chance of storm slabs increases with the amount of new snow and the amount of wind.
Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

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