Archived

Avalanche Forecast

Jan 28th, 2012–Jan 29th, 2012

Alpine

4: High

The avalanche danger rating in the alpine will be high

Treeline

4: High

The avalanche danger rating at treeline will be high

Below Treeline

3: Considerable

The avalanche danger rating below treeline will be considerable

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

3: Considerable

The avalanche danger rating below treeline will be considerable

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: Northwest Coastal.

Confidence

Fair - Intensity of incoming weather is uncertain

Weather Forecast

Saturday night: 10-15cm further snow, with the freezing level near 1300m. Strong winds. Sunday: Flurries or light snow. Strong winds easing. Freezing level gradually lowering.Monday: A moist north-west flow should bring local snow to areas very close to the coast and flurries elsewhere. Gusty westerly winds. Tuesday: Light snow, turning to moderate snow by afternoon as the next system pushes onshore.

Avalanche Summary

Several natural and explosives-triggered avalanches have been reported, with observations coming in every day this week. Many have been in the size 2-3 range, mostly failing on an instability in the storm snow and occasionally failing on facets below the storm snow.

Snowpack Summary

As one operator describes it, "oodles" of storm snow has fallen over the past week (anywhere from 1-3m). Strong winds, which have switched direction several times, have created deep wind slabs on lee- and cross-loaded slopes. Warming, heavy snow and strong winds this weekend will increase avalanche danger once again. At low elevations, rain falling on the snow could weaken surface layers and lead to large moist avalanches. Of concern deeper in the snowpack is a buried facet layer below the storm snow and a crust /facet combo which exists below treeline and recently gave easy, sudden collapse results in compression tests.

Avalanche Problems

Wind Slabs

Wind slabs may be found on many slopes due to strong, shifting winds and large amounts of snow available for transport. These overlie weak layers in the upper snowpack and can fail as very large, destructive avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Very Likely - Certain

Expected Size: 2 - 7

Storm Slabs

Weaknesses exist within and below the deep storm snow. These have been producing avalanches all week. Heavy new snow, combined with warming temperatures and wind this weekend should lead to a widespread avalanche cycle.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Very Likely

Expected Size: 1 - 7

Loose Wet

At low elevations, warming or rain could lead to loose wet avalanches which pick up mass easily and could push you around or carry you into a terrain trap.

Aspects: All aspects.

Elevations: Alpine.

Likelihood: Likely

Expected Size: 1 - 6