Avalanche Forecast

Issued: Feb 28th, 2014 8:29AM

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

triley, Avalanche Canada

Northwest Coastal.

The February weak layer continues to be a concern for triggering a very large avalanche. See the Forecaster Blog for more information.

Summary

Confidence

Fair - Wind effect is extremely variable

Weather Forecast

Overnight and Saturday: Mostly clear and cold overnight with strong Northeast winds and very strong outflow winds. Freezing level at valley bottoms and alpine temperatures near -17 overnight. Continued cold and clear with strong Northeast winds and very strong outflow winds.Sunday: Cloudy and cold with a chance of flurries or light snow. Alpine temperatures around -20 combined with strong Northeast winds.Monday: Cloudy and cold in the morning with a chance of sun in the afternoon. Alpine temperatures near -25 with strong Northerly winds.

Avalanche Summary

Explosives control resulted in avalanches up to size 2.5 that released on the February weak layer during the warm weather on Thursday. No new reports of avalanche activity since the cold arctic air moved in overnight. North aspects in the alpine continue to be the most likely slopes for triggering the February weak layer where it may be well preserved and allow for long fracture propagations resulting in very large avalanches.

Snowpack Summary

Strong solar radiation and warm temperatures have resulted in moist surface snow on all but shaded North aspects. Moist or wet loose snow has been releasing naturally from steep Southerly aspects. The early February weak layer continues to give moderate to hard sudden planar shears in snow profile tests down 50-100 cm in the North and down 100-150 cm in the South. No recent reports of whumpfing or remote triggering on this weak layer of crusts and facets. Forecast strong Northeast outflow winds may continue to develop wind slabs in areas that still have snow available for transport. 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

North aspects in the alpine are the most likely slopes for human triggering the February weak layer. Avalanches releasing on this deeply buried persistent weak layer my be 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.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

2 - 5

Wind Slabs

Very strong Easterly winds may have developed new wind slabs in areas that have snow available for transport.

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: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Valid until: Mar 1st, 2014 2:00PM