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Archived

Avalanche Forecast

Dec 11th, 2016–Dec 12th, 2016
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
1: Low
The avalanche danger rating at treeline will be low
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
1: Low
The avalanche danger rating at treeline will be low
Below Treeline
1: Low
The avalanche danger rating below treeline will be low

Regions: Kootenay Boundary.

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.

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.

Avalanche Problems

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