Avalanche Forecast

Issued: Feb 18th, 2014 8:39AM

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

triley, Avalanche Canada

Kootenay Boundary.

The storm and avalanche cycle continue. Time to scale back objectives to low angle conservative terrain.

Summary

Confidence

Fair - Forecast snowfall amounts are uncertain

Weather Forecast

Overnight and Wednesday: Expect another fast moving storm bringing 15-20 cm of snow above 1200 metres combined with strong Southwest winds. Precipitation ending by early morning as the winds become moderate Westerly.Thursday: A small pulse of moisture may bring another 3-5 cm to Southern areas of the region. Freezing levels dropping to valley bottoms overnight and rising to about 1000 metres during the day.Friday: Broken skies with some sunny periods and moderate Northwest winds. Freezing level at valley bottoms.

Avalanche Summary

Reports of natural avalanches up to size 3.0, remotely triggered avalanches by skiers or snow machines up to size 2.5, and skier accidentally triggered avalanches up to size 2.0. Just to the North of the region, one avalanche stepped down to the ground and ran full path. Those all happened on Monday, I suspect that there was less natural activity on Tuesday but conditions are primed for human triggering with long propagations. Natural avalanche activity may increase on Wednesday with forecast new snow and wind.

Snowpack Summary

The storm slab is now between 50-100 cm deep. Below the storm snow there is about 20 cm of snow from last week that buried the late January layer of crusts and/or facets and surface hoar. This persistent weak layer from Late January continues to be the sliding layer for natural and human triggered avalanches. The mid snowpack is well settled and strong. The deeply buried weak layers of early season facets and depth hoar have been dormant, but they may become reactive with the right combination of added load and warm temperatures. The forecast new snow and wind are expected to add to the load above the late January weak layer, and may result in avalanches running naturally or increased sensitivity to human triggers at this interface.

Problems

Storm Slabs

More new snow and wind are forecast overnight. Expect very touchy storm slabs that may step down to the persistent weak layer that is about a metre deep. Natural avalanches and remote triggering are likely.

The new snow will requires several days to settle and stabilize.>Avoid avalanche terrain during periods of heavy loading from new snow and wind.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

2 - 4

Persistent Slabs

Forecast new storm snow may over load the persistent weak layer resulting in very large avalanches. Storm snow avalanches in motion may step down to the buried weak layer.

Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>Avoid areas with overhead hazard.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

3 - 6

Valid until: Feb 19th, 2014 2:00PM