Avalanche Forecast

Issued: Jan 7th, 2012 9:12AM

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

Avalanche Canada Jlammers, Avalanche Canada

Summary

Confidence

Fair - Intensity of incoming weather is uncertain

Weather Forecast

Sunday: Light snowfall / moderate westerly winds / freezing level at 1000m on the west side of the region/ 2300m on the east side of the region / Monday: 8-15cm of snow / moderate westerly winds / freezing level at 1500mTuesday: Clear skies with no precipitation / winds switching to light and northerly / freezing level at surface

Avalanche Summary

Size 2 natural and human-triggered slab avalanches were reported in the region throughout the week. Size 1.5 loose snow avalanches were reported in the Elkford area on Saturday.Please visit our incident report database or our regional discussion forums on our website for more details.

Snowpack Summary

The average HS (height of snow) in the Crowsnest North is 120cms and the Crowsnest South has 150cms. As we move further West into the Elk Valley North the HS is an average of 130cms. The Elk Valley South sits at 170cms. In the Flathead the avg. HS is 170cms. All snow depths indicated are at the 2000m elevation.In the alpine and exposed slopes at treeline windward aspects have been stripped of snow by strong winds, and lee slopes have widespread stiff wind slabs. In the mid pack, weak buried surface hoar layers can be found on North-NE slopes at treeline and below down approx. 30-55cms. The surface hoar may co-exist with facets that are result of the early December dry spell. This interface is still reactive and has produced natural avalanches over the past week.At the bottom of the snowpack a variable facet/ crust/ facet sandwich is located with depth hoar up to size 5mm below the crust, and facets size 2mm above. There has been little in the way of recent activity on basal layers, but the nature of a release would be highly destructive.As a side note, the snow depths alone indicate that the region is highly variable in terms of snowpack structure. You should anticipate that layering and reactivity of weaknesses will also be variable throughout the region.

Problems

Wind Slabs

An icon showing Wind Slabs
Wind slabs can be found on lee aspects. Cross-loading is possible on open slopes oriented parallel to the wind. You may find wind slabs further down the slope or on open wind exposed areas below treeline.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 4

Persistent Slabs

An icon showing Persistent Slabs
A cohesive slab sits over a touchy surface hoar weakness buried in mid-December. This layer is still touchy and susceptible to rider triggers. Avalanches on this layer will be large, destructive and more difficult to predict.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

3 - 6

Valid until: Jan 8th, 2012 8:00AM

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