Lizard-Flathead

New snow and wind continue to drive storm slab problems on the surface. Deeper in the snowpack, persistent slab problems still can't be written off.

Moderate -

Sunday night: Flurries bringing approximately 5 cm of new snow. Strong southwest winds.Monday: Mainly cloudy with continuing isolated flurries and an uncertain trace to 10 cm of new snow. Moderate southwest winds. Freezing level near valley bottom with alpine high temperatures around -8.Tuesday: Mainly cloudy with isolated flurries and a trace of new snow, continuing overnight. Moderate to strong southwest winds. Freezing level near valley bottom with alpine high temperatures of -6.Wednesday: Cloudy with continuing scattered flurries bringing 2-5 cm of new snow with the possibility of enhanced accumulations, continuing overnight. Strong southwest winds. Freezing level rising to 1500 metres with alpine temperatures of -2.

Reports from Saturday showed explosives control in the Fernie area producing numerous storm slabs from Size 1.5-2.5. One skier triggered Size 2 was also recorded. This activity was observed above 1700 m on all but southwest aspects. An observation of a naturally triggered Size 3 persistent slab in the Fernie area shows that our persistent slab problem remains a real concern.Reports from Friday included both natural and explosives triggered storm slabs from Size 1.5-3 in the Fernie area. The Size 3 was a natural, cornice-triggered slide that failed to step down to any deeper persistent weakness. All of these occurrences were focused on north to east aspects and slab depths ranged from 20-40 cm.More active persistent slab conditions are not yet a distant memory. In the last two weeks, large avalanches ran on multiple persistent weak layers, even in fairly dense trees and on low angle slopes. Activity has gradually tapered off, but it would be wise to expect that the potential for human triggering remains.

About 40 cm of new snow has buried a new layer of feathery surface hoar on sheltered aspects (especially prominent from 1400-1900 m) as well as sun crust on solar aspects. Moderate to strong winds have been encouraging slab formation over this interface at higher elevations and continuously loading loose snow into deeper slabs in lee areas. The winds have also been also building up cornices along ridges. A thin rain crust may be present about 15cm below the snow surface at 1800 m and lower. This crust likely forms the new snow interface at lower elevations.Beneath the new snow, a number of buried weak layers have been very concerning over the past couple of weeks. A layer of surface hoar from early January is around 60 cm below the surface and the unstable weak layer from mid-December (predominantly surface hoar and/or a sun crust) is around 100 cm below the surface at treeline and below treeline elevations. A rain crust with sugary facets that developed late-November is near the bottom of the snowpack. All of these layers produced large, destructive avalanches in the last two weeks. Recent observations suggest that reactivity at these layers may finally be diminishing.