Avalanche Forecast

Issued: Dec 18th, 2014 8:26AM

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

triley, Avalanche Canada

Sea To Sky.

Avalanche danger is increasing as the new storm moves in from the Southwest.

Summary

Confidence

Fair - Freezing levels are uncertain

Weather Forecast

Snow starting today and continuing overnight should bring 15-25 cm above 1000 metres elevation. This snow will be combined with strong South to Southwest winds. Light snow (5-10 cm) and strong to very strong winds during the day on Friday combined with slightly higher freezing levels (around 1200 metres). Very strong South winds and heavy snowfall (25-35 cm) starting Saturday morning combined with forecast freezing levels climbing up to about 2000 metres. Expect another 20-30 mm of precipitation by Sunday morning before the freezing levels start to drop. This may be rain up into the alpine.

Avalanche Summary

No new avalanches have been reported. Expect new storm slab avalanche activity to increase as the storm develops.

Snowpack Summary

A new storm slab is expected to develop above the mix of current surfaces which include a mix of stubborn wind slabs and settled storm snow in the alpine, and a hard rain crust at lower elevations. Surface hoar growth has been reported in sheltered areas. There is still concern for a buried crust/facet layer which formed in November.

Problems

Storm Slabs

Forecast new snow and high winds are expected to develop a new storm slab in the alpine and at treeline.

Avoid lee and cross-loaded terrain near ridge crests.>Avoid open slopes and convex rolls at treeline where buried surface hoar may be preserved.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Deep Persistent Slabs

Although deeply buried persistent slabs have become more difficult to trigger, avalanches that release on deeply buried crystals would likely be large and destructive in nature. Use extra caution on steep, unsupported alpine terrain.

Avoid convexities or areas with a thin or variable snowpack.>Be aware of thin areas that may propogate to deeper instabilites.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

3 - 5

Valid until: Dec 19th, 2014 2:00PM