Archived

Avalanche Forecast

Dec 18th, 2012–Dec 19th, 2012

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Alpine

4: High

The avalanche danger rating in the alpine will be high

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

3: Considerable

The avalanche danger rating below treeline will be considerable

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: Kootenay Boundary.

Confidence

Good

Weather Forecast

Overnight and Wednesday: A weak ridge of High pressure will continue to cause cold and dry conditions during the day. The next Pacific frontal system is expected to move into the region by Wednesday afternoon. Light Westerly winds will become moderate Southwesterly as the storm moves in and brings 15-20 mm of precipitation, that should be snow (20-30 cms) at all elevations.Thursday: Strong Southwest winds and another 10-15 mm of precipitation for southern areas of the region. Freezing level should remain at valley bottoms.Friday: Flurries and gusty Northwest winds as a cold arctic airmass moves in from the Yukon.

Avalanche Summary

Natural soft slab and loose snow avalanches up to size 2.0 were reported to be releasing down 30-50 cms in the storm snow. Large explosive triggers released loose snow avalanches up to size 2.5 in the Kootenay Pass area.

Snowpack Summary

The storm brought another 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.

Avalanche Problems

Storm Slabs

The new storm is expected to develop a thick slab on all aspects and at all elevations. Recent light snow may also be transported by forecast strong Southwest winds into deep wind slabs on North thru East aspects.

The new snow will require several days to settle and stabilize.>Avoid freshly wind loaded features.>

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.

Avoid areas with overhead hazard.>Be cautious of sluffing in steep terrain.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 5