Avalanche Forecast

Issued: Nov 30th, 2011 8:11AM

The alpine rating is high, the treeline rating is considerable, and the below treeline rating is considerable. Known problems include Wind Slabs and Storm Slabs.

pmarshall, Avalanche Canada

Northwest Coastal.

Summary

Confidence

Fair - Due to limited field observations

Weather Forecast

A frontal system will spread light to moderate snowfall and strong SW winds on Thursday. Expect 20-30cm in coastal areas and 10-15cm near Terrace. The freezing level should be around 1000m. Conditions dry out and cool on Friday and Saturday under a NW flow. The freezing level should remain at valley bottom and upper level winds are moderate from the NW.

Avalanche Summary

Observations from Bear Pass include several natural avalanches up to Size 2.5, primarily in response to rising westerly winds on Tuesday. There are no new observations from other areas but I suspect natural avalanche activity continued on Tuesday as another storm dumped 30-50cm of new snow.

Snowpack Summary

Coastal areas are reporting a very deep and strong snowpack (+4m in some areas). Isolated wind slabs and lingering storm snow instabilities are likely over the next couple days. A buried surface hoar layer may be found down 100-150cm near Terrace, but there is no recent information on the presence and sensitivity of this layer.

Problems

Wind Slabs

Expect to find deep and dense wind slabs in exposed terrain well below ridge crests.

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Very Likely

Expected Size

2 - 5

Storm Slabs

Recent storms have dumped well over 100cm in the past few days with more snow expected on Thursday. Storm snow instabilities may be triggered by a skier or snowmobile, or by additional loading from snow or wind.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 5

Valid until: Dec 1st, 2011 8:00AM