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Archived

Avalanche Forecast

Mar 6th, 2015–Mar 7th, 2015
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
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
2: Moderate
The avalanche danger rating below treeline will be moderate
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
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Northwest Coastal.

Up to 40cm of new snow has been blown by strong winds into much deeper deposits, and large human-triggered avalanches remain a concern. Conservative terrain selection remains critical.

Confidence

Fair - Due to the number of field observations

Weather Forecast

Mainly overcast skies, strong southwest winds and very light snowfall are expected on Saturday. On Sunday and Monday a Pacific low will make landfall bringing heavy snowfall (up to 40cm) with the highest accumulations forecast for the south of the region. Winds with the storm should be strong to extreme from the southwest. Freezing levels should hover around 1000m on Saturday, spiking briefly to 1500m on Sunday, and then falling back to about 1000m on Monday

Avalanche Summary

At the time of writing, observations were extremely limited, but I expect a large, widespread natural cycle occurred in response to snow and wind-loading over the past few days. I would expect ongoing potential for human triggering of the new snow due to underlying weak surfaces. Looking forward, I would expect natural storm slab activity to ramp up again with new snow and wind forecast for Sunday and Monday.

Snowpack Summary

By Friday morning up to 40cm of new snow had fallen with the highest accumulations occurring in the southwest of the region. The new snow, moderate temperatures and strong southwest winds have likely built dense wind slabs on lee features, and storm slabs in more sheltered spots. The new snow overlies a variety of interfaces including old hard wind slabs, hard crusts, surface hoar, and/or surface facets. At the base of the snowpack, weak facets may be found, particularly on alpine slopes in the north of the region. Keep an eye out for cornices that could fail.

Avalanche Problems

Storm Slabs

Recent snowfall and strong southwest winds have built reactive new storm slabs. The new snow, which is likely to be most reactive in wind-exposed terrain, may remain touchy for some time due to underlying weak layers.
Choose conservative lines and watch for clues of instability.>Give cornices a wide berth when travelling on or below ridges.>Be cautious as you transition into wind affected terrain.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 1 - 4