Avalanche Forecast

Issued: Dec 11th, 2016 4:34PM

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

Avalanche Canada rbuhler, Avalanche Canada

Lingering wind slabs from the weekend storm are expected to remain reactive to human triggering on Monday.  Watch for signs of new wind slab formation with the forecast for moderate winds from the northwest.

Summary

Confidence

Moderate - Due to the number of field observations on Sunday

Weather Forecast

Dry conditions with a mix of sun and cloud is expected for Monday. Treeline temperatures are expected to be around -15C and alpine winds are forecast to be light to moderate from the northwest. On Tuesday and Wednesday, sunny and dry conditions are expected. Treeline temperature are forecast to remain around -15C and alpine winds are generally expected to remain light to moderate from the northwest.

Avalanche Summary

On Saturday, explosives and ski cutting triggered a few soft slabs avalanches and lots of loose activity in steep terrain features. The slabs were typically 10-30cm thick. On Friday, ski cutting was producing size 1 loose avalanches in wind loaded terrain features. On Monday, lingering wind slabs are expected to be the primary concern in wind exposed terrain.

Snowpack Summary

Around 15-25cm of new snow over the weekend has buried the surface hoar layer that formed last week. The surface hoar appears to have typically been 3-10mm in size. Widespread faceting of the old snow surface was also reported prior to the snowfall. The new snow is expected to bond poorly to the old interface but is reported to be low density and appears to only be a concern in wind loaded features at the moment. If winds persist on Monday, additional wind transport and wind slab formation is possible. The lower snowpack is settled and strong. A widespread crust that was buried in November is typically down 80-100cm. Recent tests show the layer is unreactive but cold temperatures have promoted facet growth around the crust and this layer could become a problem in the future.

Problems

Wind Slabs

An icon showing Wind Slabs
Lingering wind slabs may remain reactive to human triggering in immediately leeward terrain features.  There is also potential for additional wind loading on Monday with moderate winds from the northwest which could build new wind slabs. 
Be cautious as you transition into wind affected terrain.Use ridges or ribs to avoid pockets of wind loaded snow.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Dec 12th, 2016 2:00PM

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