Avalanche Forecast

Issued: Feb 23rd, 2014 7:41AM

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

Peter, Avalanche Canada

Northwest Coastal.

Solar radiation and significant warming could tip off a natural avalanche cycle, primarily in areas close to the coast. Outflow winds are also adding to the current challenges. Conservative decision making remains crucial.

Summary

Confidence

Fair

Weather Forecast

Monday: Mainly sunny. The freezing level is at valley bottom. Ridge winds are light to moderate from the north with strong outflow winds in coastal inlets and valleys. Tuesday: Mainly sunny. The freezing level jumps to 2300 m along the coast with a strong temperature inversion. Treeline temperatures should be near +5. Temps may remain cool further inland. Winds are light from the SW. Wednesday: A mix of sun and cloud. The freezing level on the coast remains near 2300 m and near surface inland. Winds are light and variable.

Avalanche Summary

A few large remotely triggered slab avalanches were reported in the Shames backcountry on Saturday. These were primarily from open alpine and treeline terrain and probably released on the February persistent weakness. This problem could become more touchy due to wind loading from outflow winds and/or from solar radiation. In addition, a size 2.5 accidentally triggered slab avalanche was reported in the northern part of the region. This slide released on basal facets in steep rocky alpine terrain.

Snowpack Summary

Northerly outflow winds and picked up on Saturday resulting in reverse loading and cross loading in exposed terrain at all elevations and have scoured windward slopes. The prominent mid February persistent weakness (surface hoar, facets, crust and/or wind pressed surfaces) is down 60-100 cm in the north and 120-160 cm in the south. Widespread whumpfing, cracking, natural avalanche activity and remote triggering at all elevations are a strong indication of poor bond between the new snow and these old surfaces. In addition, snowpack tests give consistent easy to moderate "pops or drops" shears on the mid Feb layer. Basal facets and/or depth hoar remain a concern in shallow snowpack areas in the northern part of the region. Cornices are also large and may become weak if northerly winds start to undercut them.

Problems

Persistent Slabs

Blue skies and fresh snow will make it very tempting to push out into more committing terrain. Don't get lured in! The current conditions are very tricky and require patience and conservative decision making.

Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>Whumpfing, shooting cracks and recent avalanches are all strong inicators of unstable snowpack.>Use conservative route selection, stick to moderate angled terrain with low consequence.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 5

Wind Slabs

Outflow winds have likely created new dense wind slabs in exposed south and west facing terrain at all elevations. Older wind slabs may still ne lurking in north and west facing terrain.

Avoid travelling in areas that have been reverse loaded by winds.>Avoid freshly wind loaded features.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 4

Valid until: Feb 24th, 2014 2:00PM