Avalanche Forecast

Issued: Dec 10th, 2012 9:22AM

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

pgoddard, Avalanche Canada

Northwest Inland.

Avalanche danger may spike to HIGH on Tuesday if strong winds continue.

Summary

Confidence

Fair - Timing, track, or intensity of incoming weather is uncertain for the entire period

Weather Forecast

Monday night: Expect winds of up to 90 km/h from the SW and about 15 cm of snow overnight. Alpine temp -6.Tuesday: Westerly winds dropping to moderate. Alpine temp -8. Light snow. Freezing level 600 m, dropping to 200 m overnight.Wed: Light NW winds. Alpine temp -8. Freezing level at surface. Light to moderate snow.Thurs: Moderate SW winds. Alpine temp -5. Freezing level 400 m. 8-10 cm snow.

Avalanche Summary

Strong W-NW winds triggered a natural avalanche cycle on Sunday, with several slabs to size 2 failing behind cross-loaded ribs and gullies. A size 2.5 slab from the headwall above the Hankin area uptrack is suspected to have failed on the Nov crust/facet layer.

Snowpack Summary

Storm snow has been redistributed by very strong W-NW winds, creating touchy wind slabs on a variety of slopes, even below treeline. In the upper snowpack, surface hoar is buried at tree line in isolated sheltered areas. A November crust/facet layer near the base of the snowpack has the potential for deep releases. Snow depths are highly variable due to the influence of recent winds.

Problems

Wind Slabs

Widespread wind slabs are likely to be found on alpine slopes and behind ridges and ribs at treeline and below.

Be aware of the potential for wide propagations due to the presence of hard windslabs.>Stay off recent wind loaded areas until the slope has had a chance to stabilize.>Use ridges or ribs to avoid pockets of wind loaded snow.>

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

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 5

Deep Persistent Slabs

A deeply buried facet/crust weakness exists. While the likelihood of triggering is relatively low, the consequences could be a very large and destructive avalanche.

Avoid shallow snowpack areas where triggering is more likely.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 6

Valid until: Dec 11th, 2012 2:00PM