Avalanche Forecast

Issued: Apr 18th, 2014 9:26AM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is moderate. Known problems include Storm Slabs, Loose Wet and Deep Persistent Slabs.

rbuhler, Avalanche Canada

Northwest Coastal.

This bulletin was created using very limited field data. If you are out in the mountains, please send your observations to forecaster@avalanche.ca

Summary

Confidence

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

Weather Forecast

Unsettled conditions and light precipitation are expected for most of Saturday before the next low pressure system hits the north coast Saturday evening. Precipitation will ease a bit during the day on Sunday before a second pulse arrives Sunday evening. Light precipitation is expected for Monday. Saturday: Precipitation 2-5mm, freezing level am: 900m pm: 1300m, ridgetop wind: moderate-strong SE-SWSat. Night: Precipitation 8-15mm, ridgetop wind: strong SE-SWSunday: Precipitation 4-6mm, freezing level am: 1000m pm: 1200m, ridgetop wind: strong SE-SWSun. Night/Monday: Precipitation 6-12mm, freezing level am: 800m pm: 1100m, ridgetop wind: moderate-strong S-SW decreasing to light SE-S

Avalanche Summary

No new reported but this is likely due to a lack of observers. Some natural avalanche activity is expected at higher elevations.

Snowpack Summary

10-40cm of new snow may sit on a crust which exists up to around 1400m on solar aspects or on last week's storm snow (90cm+ in areas of the region). Winds slabs have formed in lee features at treeline and above from strong S-SW winds.Recent warmer temperatures have helped to settle the underlying snowpack. In shallower snowpack areas or on steep, unsupported features, the old storm slab may still be reactive to human-triggering. This older storm slab is sitting on a surface hoar, a crust, and/or facets buried at the beginning of April. Large cornices may still be a concern, especially during periods of warming or heavy loading. The early February crust/facet layer is typically down 1.5 to 2.5m. A smaller avalanche or a cornice fall may still have the potential to step down to layer causing very large, destructive avalanches.

Problems

Storm Slabs

New snow is expected to form widespread storm slabs and stiffer wind slabs in leeward features. It may still be possible to trigger the thicker, older storm slab from the last storm, especially on steep unsupported slopes and thinner snowpack areas.

Be cautious as you transition into wind affected terrain.>Avoid unsupported slopes.>Make observations and assess conditions continually as you travel.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Loose Wet

Rain at lower elevations will saturate and destabilize the upper snowpack. Loose sluffing from steep terrain features is possible, especially from human-triggering.

Be cautious of sluffing in steep terrain.>Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2

Deep Persistent Slabs

A deeply buried persistent weak layer still has the potential to produce very large avalanches and could be triggered by heavy triggers such as cornice falls or smaller avalanches stepping-down.

There is potential for large, deep avalanches due to the presence of buried facets and surface hoar.>Conditions have improved, but be mindful that deep instabilities are still present.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely

Expected Size

3 - 7

Valid until: Apr 19th, 2014 2:00PM