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Archived

Avalanche Forecast

Feb 27th, 2013–Feb 28th, 2013
Alpine
4: High
The avalanche danger rating in the alpine will be high
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
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
4: High
The avalanche danger rating below treeline will be high
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

Regions: South Coast.

Confidence

Fair - Timing, track, or intensity of incoming weather is uncertain on Thursday

Weather Forecast

A very wet flow (Pineapple Express) is forecast, but exactly when and where the intense precipitation will occur is a matter of great uncertainty.  Thursday-Saturday: Moderate to heavy precipitation. Strong to extreme SW winds. Freezing level around 1600 m, rising for a time to 2000 m.

Avalanche Summary

Numerous skier-triggered slabs have been triggered remotely, propagating across surprising distances and generally surprising people at all elevations. Details of some of these recent incidents can be found here. A natural cycle to size 2.5 occurred on Sunday night and Monday in response to new snow and wind-loading. Expect more avalanche activity over the next few days.

Snowpack Summary

Two very touchy weaknesses of surface hoar and/or a crust within the upper metre or so of the snowpack have already been responsible for a number of avalanche incidents. Add an intense storm, with heavy precipitation rates, warming and very strong winds, and we have a good recipe for widespread avalanche activity. The lower snowpack is well settled.

Avalanche Problems

Storm Slabs

Storm snow is expected to become very touchy with continuous loading throughout the forecast period, especially where wind-loaded. Storm slabs may step down to persistent weaknesses, creating very large avalanches.
Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>Give cornices a wide berth when travelling on or below ridges.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 5

Persistent Slabs

Persistent weaknesses buried last week demand respect, as they are very touchy, can be triggered from a distance, and are leading to surprisingly large avalanches.
Be aware of the potential for large, deep avalanches due to the presence of persistent weak layers.>Remote triggering is a concern, watch out for adjacent slopes.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 2 - 6