Avalanche Forecast

Issued: Dec 20th, 2012 10:06AM

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

jfloyer, Avalanche Canada

Kootenay Boundary.

If more than 20 cm new snow arrives by Friday morning with wind, bump danger levels up by one for all elevations.

Summary

Confidence

Poor - Intensity of incoming weather is uncertain

Weather Forecast

Friday: Snowfall is expected to continue overnight Thursday but taper off Friday morning. Up to 10 cm can be expected by noon on Friday. Treeline temperatures are expected to be around -4C. Winds moderate southerly.Saturday: The region could see another good hit of snow Friday night, with a possibility for 10-15 cm of new snow by Saturday morning and maybe a little more during the day. Treeline temperatures falling to around -6. Winds gusting to around 60 km/h from the SW.Sunday: Flurries or light snowfall. Temperatures continuing their downward trend. Winds light southwesterly.

Avalanche Summary

On Thursday, machine-triggered avalanches were reported running at the base of the most recent storm snow down 20 to 50 cm. Explosive testing produced avalanche up to size 2.5 in the storm snow at elevations around 2000 m.On Wednesday, natural and skier-triggered avalanches up to size 2.0 were reported to be releasing down 30-50 cms in the storm snow.

Snowpack Summary

The most recent storm brought 20-40 cms of dry light snow combined with moderate to strong Southwest winds. The storm slab has been very easy to trigger in areas where the wind stiffened the slab a bit. In most places the slab is still soft to very soft and it is not propagating far. Expect heavy sluffing in steep terrain. The well settled mid-pack has not been showing shears in snow profile tests.

Problems

Storm Slabs

With slightly warmer temperatures, the new storm may develop a denser surface slab. Recent light snow may also be transported by forecast strong southwest winds into deep wind slabs on north through east aspects.

Note recent avalanche activity.>Be cautious as you transition into wind affected terrain.>Whumpfing, shooting cracks and recent avalanches are all strong indicators of an unstable snowpack.>The best powder will be found in sheltered locations at or below treeline.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

2 - 5

Loose Dry

Loose dry snow remains unconsolidated in terrain that is protected from the wind. There is a lot of new snow; sluffing may entrain enough snow to bury a skier/rider.

Be cautious of sluffing in steep terrain.>On steep slopes, pull over periodically or cut into a new line to manage sluffing.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 5

Valid until: Dec 21st, 2012 2:00PM