Avalanche Forecast

Issued: Feb 11th, 2013 3:00PM

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

Avalanche Canada jfloyer, Avalanche Canada

Summary

Confidence

Good

Weather Forecast

Synopsis: A frontal system moves through the region late on Tuesday bringing light snowfall Tuesday night. On Wednesday afternoon and Thursday, a ridge of high pressure builds in the region.Tuesday: Flurries. Light SW winds increasing at the end of the day. Freezing level around 1000m.Wednesday: Around 5 cm new snow, which should end by noon. Clearing in the afternoon. Freezing level around 1200m. Strong westerly winds in the morning, diminishing through the day.Thursday: Dry and sunny. Freezing level 800m in the afternoon. Light NW winds.

Avalanche Summary

There were two size 1 human-triggered avalanches reported from Saturday on north aspects in recent new snow with crowns of 10-20 cm. Loose snow avalanches were reported over the weekend on steep solar aspects. On Sunday, several small (size 1) human-triggered avalanches were reported in buried surface hoar from just outside the region on north aspect slopes.

Snowpack Summary

The snow surface consists of a sun crust, surface hoar, or a dusting of new snow. Below this approximately 15-20 cm of recent storm snow has been redistributed into soft wind slabs at higher elevations. The new snow overlies a gamut of old surfaces which include old wind slabs at higher elevations, fairly widespread surface hoar, and a melt-freeze crust on previously sun-exposed slopes. This interface will be something to watch as the overlying slab develops. About 35-50cm below the surface is another interface of surface hoar or a sun crust that was buried on Jan 23. It is hard to find in some areas and seems to be gaining strength where it is found, but this weakness is still on the radar of professionals in the region. The snowpack below this is generally well settled and bonded.

Problems

Wind Slabs

An icon showing Wind Slabs
Triggering is possible on steep gully sidewalls and in the lee of ridge crests.
Watch freshly wind loaded features.>Use ridges or ribs to avoid pockets of wind loaded snow.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

An icon showing Persistent Slabs
An assortment of weak crystals is buried between 35 and 50cm below the surface. Although this interface is gaining strength, triggering may still be possible in unsupported terrain.
Dig down to find and test weak layers before committing to a line.>Choose well supported terrain without convexities.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

1 - 4

Valid until: Feb 12th, 2013 2:00PM

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