Avalanche Forecast

Issued: Jan 16th, 2013 8:49AM

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

Peter, Avalanche Canada

Sea To Sky.

Summary

Confidence

Good

Weather Forecast

Synopsis: The upper ridge of high pressure continues to dominate the weather for the South Coast. The next few days should see mainly clear skies with possible valley cloud. The above freezing layer between 1000 and 3000 m should remain. Winds are generally moderate to strong from the northwest.

Avalanche Summary

On Wednesday there were reports of a few small loose wet avalanches on steep sun exposed slopes, and couple accidentally skier-triggered size 1 slab or loose snow avalanches in steep south facing terrain.

Snowpack Summary

The snow surface consists of thin new wind slabs, a sun crust, moist snow, dry faceted snow, or large surface hoar depending on aspect, elevation, and time of day. Below this 40-70 cm of recent storm snow sits on a persistent weakness of surface hoar, facetted snow, and/or a crust buried at the beginning of January. Reports from last weekend include a Rutschblock Score of 3 down 52cm on a thin crust in the Whistler area, and hard compression test results on distinct surface hoar on a northeast facing open glade below treeline in the Chehalis (northwest of Hope). No significant weaknesses have been reported recently below this in the mid snowpack layers. Near the base of the snowpack, a crust/facet layer exists, which is now unlikely to be triggered, except perhaps by heavy triggers in steep, shallow, rocky terrain where more facetting has taken place.

Problems

Persistent Slabs

Warm temperatures and solar radiation will increase the probability of avalanches releasing on a buried weak layer of surface hoar, facets, and/or a crust, down 40-70 cm.

Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 5

Wind Slabs

Strong northwesterly winds have created new wind slabs in exposed lee and cross-loaded terrain features.

Be cautious as you transition into wind affected terrain.>Avoid cross loaded slopes at or above treeline.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Loose Wet

Loose wet activity is expected as temperatures rise. A loose wet slide could step down and trigger weaknesses deeper in the snowpack.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Jan 17th, 2013 2:00PM