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Avalanche Forecast

Mar 30th, 2015–Mar 31st, 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
1: Low
The avalanche danger rating below treeline will be low
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
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

Regions: Sea To Sky.

Large and destructive avalanches will remain a concern long after the stormy weather has ended. See this blog post for additional info: http://bit.ly/1HHQrK2

Confidence

Fair - Due to the number of field observations

Weather Forecast

A general cooling pattern is expected for the forecast period. On Tuesday, Wednesday and Thursday only trace amounts of new snow are expected each day with the possibility of occasional sunny breaks. Ridgetop winds should remain light to moderate from the northwest with daytime freezing levels hovering at about 1300m

Avalanche Summary

We have not yet heard how avalanche activity panned out in response to the recent storms, due to limited visibility and the challenges of backcountry travel at this time. We have previously had ongoing reports of very large slab avalanches running on the mid-March persistent weak layer. I would be very surprised if this layer has not performed during the recent storm cycle.

Snowpack Summary

This region is dealing with a very serious persistent slab problem that is currently being subjected to significant additional loading by new snow and/or rain. Depending on how much recent snow has fallen, a facet/crust persistent weak layer buried mid-March lies anywhere from 50-150 cm below the surface. This interface has been incredibly volatile recently and remains sensitive to both human and natural triggering, especially where the slab is thinner. Recent compression tests have produced sudden planar failures at this interface. At lower elevations, rain has saturated the snowpack. Layers below the critical mid-March interface are generally considered to be well-settled and strong.

Avalanche Problems

Persistent Slabs

A deeply buried persistent weak layer continues to haunt the region with the potential for very large and destructive avalanches. Conservative terrain selection remains critical.
Remote triggering is a concern, watch out for adjacent slopes.>Be aware of the potential for large, deep avalanches due to the presence of a buried crust/facet layer.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 3 - 6

Storm Slabs

Wind and snow on Monday will form new storm slabs. Watch for increased reactivity in high elevation lee terrain.
Stay off recent wind loaded areas until the slope has had a chance to stabilize.>Be alert to conditions that change with elevation.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 4