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Archived

Avalanche Forecast

Mar 13th, 2017–Mar 14th, 2017
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
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
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable

Regions: Northwest Coastal.

Another heavy storm pulse will sustain very dangerous avalanche conditions on Tuesday.

Confidence

Moderate - Freezing levels are uncertain

Weather Forecast

TUESDAY: The next storm starts late Monday night bringing 20-40 cm, strong southwest winds, freezing level dropping with alpine temperatures around -3 C.WENDESDAY: Lingering flurries with 10-20 cm, moderate southwest winds, alpine temperatures around - 7 C.THURSDAY: Another 10-30 cm of snow, strong southwest winds, alpine temperatures around -7 C.

Avalanche Summary

A large natural avalanche cycle likely occurred during the peak of the storm on Sunday night. A few reports of small skier triggered slabs were reported in the early stages of the storm on Sunday, but poor visibility has limited field observations. Persistent slab avalanches on the February interface were reported on a daily basis prior to the storm. The current storm has all the ingredients for large widespread storm slabs. On top of that, it will also trigger very large persistent slab avalanches on buried weak layers.

Snowpack Summary

Storm slabs will continue to grow on Tuesday with another 20-40 cm of snow and strong winds in the forecast. This comes in the wake of Sunday's 30-60 cm storm. The overall results will be widespread touchy storm slabs at higher elevations and unstable wet snow at lower elevations. The storm snow is also stressing a weak interface from February composed of facets, crust, and surface hoar buried over a metre deep. Given the recent activity on this layer before the storm, it should be very reactive during this storm. The lower snowpack is strong, with the exception of basal facets in shallow snowpack areas around Bear Pass and Ningunsaw.

Avalanche Problems

Storm Slabs

Another round of large slab avalanche activity is expected on Tuesday with the next storm pulse.
Travel in avalanche terrain is not recommended with current conditions.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Very Likely

Expected Size: 2 - 3

Persistent Slabs

The new snow will also trigger large avalanches on a reactive weak layer buried over a metre deep.
Avoid all avalanche terrain.Be aware of the potential for full depth avalanches due to deeply buried weak layers.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 2 - 4