South Columbia

Change is finally coming as the first in a series of storms strikes the region Sunday night. Not much snow to start, but strong alpine winds are putting the focus on wind slab problems for Monday.

High -

Sunday night: Cloudy with flurries bringing 3-6 cm of new snow. Mainly light south winds, increasing to strong southwest in the alpine.Monday: Cloudy with easing flurries bringing another trace to 2 cm of new snow. Light to moderate southwest to northwest winds. Alpine high temperatures around -7.Tuesday: Cloudy with another round of flurries bringing approximately 5 cm of new snow and increasing a bit overnight. Moderate to strong south to southwest winds. Alpine high temperatures around -7.Wednesday: Mainly cloudy with easing flurries leaving another 2-3 cm of new snow before increasing again in the evening. Strong northwest winds. Alpine high temperatures around -8.

A MIN report from Saturday in the Keefer lake area describes a recent large (size 2) slab that released naturally from a steeper, open feature below treeline. The failure plane of the slab is uncertain but it suspected to be one of our mid-November surface hoar layers, possibly where it is combined with an underlying crust. The report also describes another snowmobile-triggered avalanche that occurred in the Kaslo area. Details on the incident are not complete but suggest that at least one individual was partly buried.Shallow size 1 loose dry avalanches were sensitive to skier traffic on Friday. A size 1 human triggered storm slab avalanche was also reported from a steep north facing feature at 2400 m.

Increasing high elevation winds are expected to be forming new wind slabs on the surface in the alpine. Beneath the surface, the snowpack is generally stable but does hold a lingering weak layer about 35-65 cm deep. This layer consists mainly of weak, feathery surface hoar crystals that is most prominent at treeline, but may also be found in sheltered alpine areas. Although this surface hoar is gradually healing into the snowpack, recent snowpack tests in the region suggest that this layer may remain problematic in places where the surface hoar formed above a sun crust. This combination is most likely found on south aspects at treeline.At the base of the snowpack is a crust that formed near the end of October. Concern for this layer is dwindling but it may still be worth considering in places such as steep, rocky, alpine terrain, especially where the snowpack is shallow. It would likely take a large trigger such as a cornice fall to produce an avalanche on this layer.