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Archived

Avalanche Forecast

Mar 8th, 2015–Mar 9th, 2015
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
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
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
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Northwest Coastal.

Heavy snowfall and strong winds will push the Avalanche Danger to High.

Confidence

Fair - Intensity of incoming weather systems is uncertain on Monday

Weather Forecast

Expect lingering snowfall (up to 15cm) on Monday morning as Sunday's storm tapers-off. A clearing trend is forecast for late Monday and Tuesday. By Wednesday, a strong Pacific low will deliver another round of moderate to heavy snowfall. Ridgetop winds will remain moderate to strong from the southwest on Monday, decreasing somewhat on Tuesday, and then becoming strong and southwesterly with Wednesday's storm. Freezing levels should hover around 600m for the forecast period.

Avalanche Summary

There was surprisingly little reported avalanche activity given the amount of new snow and wind on Thursday and Friday. Size 1 soft slabs were reportedly sensitive to human triggering in high elevation lee terrain. Looking forward, more wind and snow on Sunday and Monday will likely spark a round of natural storm slab activity. New new snow will also add more stress to these recently buried weaknesses.

Snowpack Summary

Just before the weekend, between 10 and 40cm of new snow fell with the highest accumulations occurring in the southwest of the region. The new snow and strong southwest winds built dense slabs on exposed lee features. Locally heavy snowfall and strong winds on Sunday and Monday morning will add size and destructive potential to this developing storm slab. Below the recent storm snow you'll find a variety of interfaces including old hard wind slabs, hard crusts, surface hoar, and/or surface facets. Some reports suggest a reasonable bond at this interface, although I'd remain cautious on steeper, high-consequence slopes as a release on recently buried surfaces could be large and destructive .At the base of the snowpack, weak facets may be found, particularly on alpine slopes in the north of the region. Cornices are reported to be large and potentially unstable.

Avalanche Problems

Storm Slabs

Heavy snowfall and strong winds will build reactive new storm slabs. Watch for increased reactivity in higher-elevation lee terrain.
Choose conservative lines and watch for clues of instability.>Be cautious as you transition into wind affected terrain.>Stay well back from cornices.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 1 - 4