Avalanche Forecast

Issued: Mar 8th, 2013 9:05AM

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

jlammers, Avalanche Canada

Sea To Sky.

Summary

Confidence

Fair - Timing, track, or intensity of incoming weather is uncertain on Sunday

Weather Forecast

A ridge of high pressure should persist for one more day bringing mainly clear skies for Saturday. Winds are expected to be light and northwesterly with the freezing level at 1900m.The ridge then flattens and a more zonal pattern is forecast to bring snowfall and seasonal temperatures to the region for Sunday and Monday. At this point there is significant model disagreement with the timing and intensity of this next system.

Avalanche Summary

Size 1 loose wet avalanches were reported from the region occurring in steep, south-facing terrain. With forecast warming on Saturday, I would expect ongoing wet snow instabilities with the potential to trigger deeper persistent weaknesses in isolated terrain.

Snowpack Summary

Light snowfall overlies wind slabs in exposed areas, surface hoar or facets in sheltered locations, or a sun crust on south facing terrain.Below the surface, last week's accumulations of 70-120cm continue to settle and strengthen. A weakness of surface hoar and/or a crust exists near the base of the storm snow (now 1-2 m deep in some locations). This layer was the culprit in most of the large avalanches that occurred last weekend. This layer could still be triggered in shallow rocky areas or by large triggers like a cornice fall. I would suggest avoiding any large slope that did not release during the latest avalanche cycle, especially with forecast solar warming on Saturday. Below this interface, the snowpack is strong and well settled.

Problems

Loose Wet

With forecast sun, loose wet avalanches will become likely on steep, sun-exposed slopes.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>

Aspects: North, North East, East.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 3

Persistent Slabs

A buried layer of surface hoar or a sun crust is now down 100-200 cm. It may be possible to trigger this layer in steep terrain, especially with forecast warming. The resulting avalanche could have serious consequences.

Conditions have improved, but be mindful that deep instabilities are still present.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 6

Cornices

Cornices have grown large and weak in recent storms. Solar warming could be enough to cause cornices to fail.

Give cornices a wide berth when travelling on or below ridges.>

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

2 - 6

Valid until: Mar 9th, 2013 2:00PM