Avalanche Forecast

Issued: Feb 28th, 2014 8:25AM

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

Avalanche Canada triley, Avalanche Canada

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 - Forecast snowfall amounts are uncertain

Weather Forecast

Overnight and Saturday: Cold and clear overnight with no precipitation and light Northwest winds. Cloud developing in the morning as the winds shift to the West. Light to moderate snowfall during the afternoon with freezing levels at or near sea level. Sunday: Southwest winds building to moderate, pushing moisture further inland against the arctic cold front. Expect 10-20 cm of snow near the coast and 5-10 cm further inland.Monday: Another 5-10 cm of snow combined with strong Southwest winds and freezing levels climbing up to about 1500 metres in the afternoon.

Avalanche Summary

No new avalanche activity reported since the cold arctic air moved into the region overnight. Deep releases on the February layer are most likely to continue from North aspects in the alpine where shaded slopes have not settled and bonded and the weak layer is well preserved.

Snowpack Summary

Cold air that moved down from the arctic has developed a melt-freeze crust on all aspects at lower elevations, and on all but Northerly aspects in the alpine. Recent very warm temperatures and periods of very strong solar radiation caused a great deal of settlement in the old storm slab above the early February weak layer. The February weak layer of crusts and facets has been reported to be rounding and bonding in areas where the old storm slab is 200 cm or deeper ( there is between 2-3 metres of snow above the weak layer in the Coquihalla area). Shallow snow pack areas where the old storm slab is closer to a metre or less continue to give sudden planar shears in snow profile tests ( there is about 60-80 cm above the weak layer in the Duffey Lake area). North aspects in the alpine may have had enough warming to settle the storm snow into a cohesive slab, but not enough to improve the weak layer bond. Big un-supported alpine North aspects are the most likely place to find a well preserved deeply buried February weak layer that may continue to allow for long propagations resulting in very large avalanches.

Problems

Persistent Slabs

An icon showing Persistent Slabs
Human triggering with long fracture propagation resulting in very large avalanches continues to be a concern. North aspects in the alpine are the most likely slopes to have a well preserved weak layer with a cohesive slab above.
Stick to simple terrain and be aware of what is above you at all times.>Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

3 - 6

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

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