Avalanche Forecast

Issued: Feb 28th, 2014 8:20AM

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

triley, Avalanche Canada

Northwest Inland.

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

No new avalanche activity reported.

Snowpack Summary

The recent warm air over most of the forecast regions did not push into the Northwest Inland. Temperatures remained cool even with solar radiation, and now the temperatures have dropped to very cold with the influence of arctic air sliding down from the Northeast. The early February weak layer of facets, crusts, and surface hoar is buried down about 35-90 cm. The snow above the crust has been transported by Southwest winds and then reverse loaded by Easterly or Southeast winds. Cold temperatures have not settled the snow above the weak layer into a cohesive slab, and the cold has preserved the weak layer and associated crusts. I suspect that there will not be much change or improvement in the bonding of the late February snow to the crusts and facets. Snow pack tests may help to show when this layer demonstrates more resistance to added forces.

Problems

Persistent Slabs

Continued cold temperatures are expected to preserve the buried February weak layer of facets and crusts. Avalanche fractures may propagate further if the old storm snow above the weak layers settles into a cohesive slab.

Use conservative route selection, stick to moderate angled terrain with low consequence.>Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 4

Wind Slabs

Strong Easterly winds may develop new wind slabs in areas that have snow available for transport.

Use ridges or ribs to avoid pockets of wind loaded snow.>Be cautious as you transition into wind affected terrain.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

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