Avalanche Forecast

Issued: Dec 19th, 2012 8:57AM

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

Avalanche Canada triley, Avalanche Canada

Summary

Confidence

Fair - Forecast snowfall amounts are uncertain on Thursday

Weather Forecast

Overnight and Thursday: Strong Southerly winds and moderate to locally heavy precipitation 5-10 mm by morning that will be snow at all elevations (10-20 cms). This storm is expected to continue during the day; however snow fall amounts vary between models. This bulletin is based on another 10-15 mm (20-30 cms at higher elevations) of precipitation before the storm moves out of the region to the East. Freezing levels are expected to remain at valley bottoms except a brief period on Thursday where they may rise to just above valley bottoms.Friday: Light flurries are expected in the wake of the storm as residual moisture collides with the cold air moving in from the North. Expect winds to shift to the East-Northeast during the day.Saturday: Continued light flurries for the areas near the U.S. border. Alpine temperatures near -20.0 with light Northeast winds are expected during the day.

Avalanche Summary

No new observations.

Snowpack Summary

In the South Elk valley (West of Sparwood) today the height of snow was 160 cms at 1800 metres elevation. The top 20 cms was the recent storm snow. The height of snow was 220 cms at 2000 metres. The field team was looking for the early December crust that has been reported to be active in the Lizard range. They found a crust about 20 cms above the ground (probably the early November crust) and another crust about 90 cms above the ground that was probably the early December crust.  Snow profile tests did not show any shears on either of these layers in this location. Watch for the new snow and wind on Thursday to transport snow into a storm slab on all aspects and wind slabs on exposed terrain at higher elevations.

Problems

Storm Slabs

An icon showing Storm Slabs
The new storm is expected to develop a storm slab on all aspects. The forecast strong SW winds may transport storm snow into thick and touchy slabs on North thru East aspects.
The new snow will require several days to settle and stabilize.>Avoid freshly wind loaded features.>Avoid unsupported slopes.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 5

Valid until: Dec 20th, 2012 2:00PM

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