Avalanche Forecast

Issued: Feb 5th, 2013 9:40AM

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

mpeter, Avalanche Canada

South Coast.

Summary

Confidence

Good

Weather Forecast

Wednesday: Expect cloudy skies with flurries and strong southwesterly winds with alpine temperatures reaching -7. 5-15cm are possible.Thursday: Continuing cloudy, with a chance of lingering flurries. Winds should turn more northerly and ease to light values with alpine temperatures reaching -5.Friday: Mixed skies with continued light northerly winds and temperatures around -3.

Avalanche Summary

Isolated windslab events have been reported from alpine lee zones. As the storm snow deepens, expect the avalanche activity to pick up.

Snowpack Summary

Between 15-25cm of new snow has fallen in the past 36hrs. Consistent southwesterly winds have redistributed this into fresh windslabs on lee terrain features in the alpine and at treeline. Freezing levels have crept up higher than expected yielding moist surface snow up to 1600m in some locations. A new surface crust below treeline will be the outcome of this warming.The newly buried surfaces are old wind slabs (behind ridges, ribs and on lee slopes) and sun crusts on south and west facing slopes. Down a further 20-50 cm sits a persistent interface comprising of crusts, facets and surface hoar crystals. Recently, this layer has been reactive only in sheltered areas at and below treeline where the surface hoar lingers. The mid pack is generally well settled.

Problems

Wind Slabs

New windslabs are forming with new snow and consistent southwesterly winds. Isolated old slabs may still be reactive in lee and cross loaded features.

Be cautious as you transition into wind affected terrain.>Highmark or enter your line well below ridge crests to avoid wind loaded pillows.>

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Persistent Slabs

Buried down 30-60 cm exists a surface hoar/crust/facet layer. This layer of concern seems to be most reactive in sheltered locations over convex rolls and steeper terrain features at treeline and below.

Dig down to find and test weak layers before committing to a line.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 5

Valid until: Feb 6th, 2013 2:00PM