Avalanche Forecast

Issued: Apr 15th, 2014 9:57AM

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

slemieux, Avalanche Canada

Northwest Coastal.

This bulletin has been produced using very limited field data. If you've been out in the mountains we'd love to hear about what you've seen. Observations can be sent to forecaster@avalanche.ca

Summary

Confidence

Fair - Due to the number of field observations

Weather Forecast

Tonight and Wednesday: A frontal system is forecasted to approach the coast spreading light to moderate precipitation (~15 mm in water equivalent) into Wednesday. Freezing levels around 1200 m with moderate South East winds. Thursday: Heavy precipitation is expected (~30 mm) with freezing levels around 1100 m and moderate to strong winds from the South West. Friday: A break in precipitation before the next system approaches the coast late in the day. Freezing levels around 1100 m and light South winds.

Avalanche Summary

A slab avalanche size 2.5 was remotely triggered yesterday on a North facing alpine slope in the North Eastern part of the region. This slab would have run on the deep persistent weak layer buried in mid-February.

Snowpack Summary

Forecasted light to moderate accumulations mostly over the Southern part of the region should fall over a surface crust on solar aspects up to around 1400 m or onto last week's storm snow which brought 90+ cm or more to the coastal region. This storm layer is expected to bond poorly to the underlying surfaces and to form touchy windslabs in the alpine lee of the forecasted moderate South East winds.Recent warmer temperatures have helped to settle the underlying snowpack. Although, it has been reported to be reactive to skier traffic on steeper/shallower slopes since it is where it is sitting on a surface hoar, crusts and/or facets buried at the beginning of April. Large cornices have formed and loom over slopes below. The early February crust/facet layer is down 150 - 240 cm. An avalanche could step down to this destructive layer from a cornice fall or from a storm slab being triggered.

Problems

Storm Slabs

Forecast snowfall will add to existing deep storm slabs which formed last week. Although these storms slabs have become less likely to trigger, large avalanches may still result where they overlie weak layers buried at the beginning of April.

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 4

Deep Persistent Slabs

Deep and destructive persistent slab avalanches will become less likely with the forecast cooling trend. Possible triggers include cornice fall, warming and intense solar radiation.

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely

Expected Size

3 - 7

Valid until: Apr 16th, 2014 2:00PM