Avalanche Forecast

Issued: Feb 21st, 2013 8:26AM

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

pmarshall, Avalanche Canada

Northwest Coastal.

Summary

Confidence

Fair - Timing of incoming weather is uncertain

Weather Forecast

Synopsis: A series of frontal systems is expected to affect the region over the next few days. The strongest system is on track for Friday. Friday: Heavy snowfall – 20-30 cm. The freezing level remains around 500-600 m and winds are moderate to strong from the west.Saturday: Cloudy with light snow. The freezing level is around 500 m and winds ease to moderate from the southwest. Sunday: Moderate to locally heavy snow. The freezing level is around 400-500 m.

Avalanche Summary

Most recent activity on Wednesday was limited to small loose wet or dry avalanches in steep terrain; however, observations were limited due to poor visibility.

Snowpack Summary

15-25 cm of new snow overlays a crust, old wind slab, or surface hoar depending on aspect and elevation. Pockets of new wind slab are likely in lee or ridges and terrain features and in cross-loaded gullies. Below this the recent storm snow has settled and gained strength over the past couple days. Cornices that now loom over many features may become weak with continued growth and/or daytime warming. The mid and lower snowpack layers are generally well settled.

Problems

Storm Slabs

New snow may not bond well to the previous snow surface (surface hoar, wind slab, crust) and may be easily triggered by additional loading. Be especially wary of exposed north through east facing slopes where wind loading is likely.

Stick to non-avalanche terrain or small features with limited consequence.>Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>Be cautious as you transition into wind affected terrain.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

2 - 6

Cornices

The recent snow and wind have been building cornices on lee features. These cornices are likely weak and may fail at anytime. Cornice failure has the potential to trigger large avalanches.

Give cornices a wide berth when travelling on or below ridges.>

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Valid until: Feb 22nd, 2013 2:00PM