Avalanche Forecast

Issued: Mar 4th, 2014 7:57AM

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

swerner, Avalanche Canada

Northwest Inland.

Check out the Forecaster Blog for more information on the persistent weak layer.

Summary

Confidence

Fair - Wind effect is extremely variable

Weather Forecast

A fairly benign weather pattern until Friday. The pattern will then change and the region will see light amounts of precipitation, rising freezing levels and strong SW winds.Wednesday: Mix of sun and cloud. Alpine temperatures near -15.0. Ridgetop winds moderate from the SE. Slight alpine temperature inversion.Thursday: Snow amounts 5 cm. Alpine temperatures -15.0. Ridgetop winds moderate from the SE. Freezing levels valley bottom with a strong alpine temperature inversion.Friday: Snow amounts 5-10 cm. Alpine temperatures -5.0. Ridgetop winds light-moderate from the SW. Freezing levels 500 m with an alpine temperature inversion.

Avalanche Summary

No new avalanche activity reported.

Snowpack Summary

Temperatures have 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. Surfaces are seeing significant new surface hoar growth and surface facetting, especially in treeline and below. 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

Expected Size

2 - 5

Wind Slabs

Continued strong Easterly winds are expected to scour leeward slopes and develop hard 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

Possible

Expected Size

1 - 3

Valid until: Mar 5th, 2014 2:00PM