Avalanche Forecast

Issued: Feb 24th, 2014 7:34AM

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

Peter, Avalanche Canada

Northwest Coastal.

Avalanche danger will rise on Tuesday due to rapidly rising temperatures and the presence of a significant buried persistent weak layer. Stick to low angle terrain that is not exposed to overhead avalanche paths.

Summary

Confidence

Fair

Weather Forecast

Tuesday: Mainly sunny. A strong alpine temperature inversion is likely between 1500 and 2300 m. Treeline temperatures should be near +5. Temps may remain cooler further inland. Outflow winds should ease off during the day. Â 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.Thursday: A mix of sun and cloud with a chance of precipitation near the coast. The freezing level on the coast remains near 2000 m and near surface inland. Winds are light and variable.

Avalanche Summary

Numerous natural and skier triggered wind slabs up to size 2 were reported on Sunday in response to the outflow winds. 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. In addition, a size 2.5 accidentally triggered slab avalanche was reported in the northern part of the region on saturday. This slide released on basal facets in steep rocky alpine terrain.

Snowpack Summary

Strong N-SE outflow winds have resulted in reverse loading and cross loading in exposed terrain at all elevations, and have scoured exposed 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. Snowpack tests are now giving moderate to hard "pops or drops" shears on this weakness, and several whumpfs are still being reported. 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

Rapidly rising temperatures will likely increase the probability of avalanches releasing on the buried mid February persistent weak layer. The resulting slides could be very large and destructive.

Use conservative route selection, stick to moderate angled terrain with low consequence.>Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 5

Wind Slabs

Outflow winds have created touchy wind slabs in exposed lee and cross-loaded terrain at all elevations.

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

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

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 4

Loose Wet

A loose wet avalanche could drag you somewhere you don't want to end up, but could also be enough mass to trigger a large slab avalanche.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Minimize exposure to sun exposed slopes when the solar radiation is strong.>

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

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 3

Valid until: Feb 25th, 2014 2:00PM