Avalanche Forecast

Issued: Dec 4th, 2011 9:06AM

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

Avalanche Canada ghelgeson, Avalanche Canada

Summary

Confidence

Poor - Due to limited field observations

Weather Forecast

A radical above freezing layer is forecasted for Sunday night into Monday. Freezing levels as high as 2800m are possible. A cold front sweeps across the NW coast bringing as much as 30mm to the more coastal locations Monday afternoon as ridgetop winds build to 80 - 95 km/h out of the W. Freezing levels lower Monday as the cold front moves inland.Cold post frontal air keeps the region dry & cool on Tuesday. Ridge of high pressure rebuilds Wednesday & Thursday with an outflow pattern. Another above freezing layer is forecasted for later in the week.

Avalanche Summary

Natural and explosive controlled avalanches up to size 4.0 releasing in the storm snow. Some of the larger releases have been from glide avalanches. Most of this activity is in the West of the region closer to the coast. We don't have any new reports from the Interior.

Snowpack Summary

Very strong W-SW winds have probably wreaked havoc in any exposed terrain. Expect to find scoured areas, sastrugi, and hard or stiff wind slabs. The average snowpack depth at treeline is over 200cm. The mid and lower snowpack are generally quite strong. Watch for clues of instability like whumpfs or shooting cracks, and if observed back off any steeper objectives.

Problems

Wind Slabs

An icon showing Wind Slabs
Big westerly winds combined with new snow will create fresh sensitive windslabs on lee aspects. These new windslabs will be burying old hard windslabs that may still be sensitive to human triggers.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Storm Slabs

An icon showing Storm Slabs
Storm slabs will be an increasing problem throughout the day Monday. Carefully re-evaluate each run to account for changing conditions.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 3

Valid until: Dec 5th, 2011 8:00AM

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