Avalanche Forecast

Moderate - Freezing levels are uncertain

Friday night: Mainly cloudy. Light southwest winds, increasing to strong northwest in the alpine. Saturday: Mainly cloudy with a chance of isolated flurries and a trace of new snow. Light southwest winds, increasing to strong northwest in the alpine, extreme overnight winds. Alpine high temperatures around 0 with a strong chance of an alpine temperature inversion bringing alpine temperatures well above freezing.Sunday: Cloudy with sunny periods. Strong to extreme northwest winds easing over the day. Alpine temperatures falling from around 0 to -6 as freezing levels decline from 2000 to 1000 metres.Monday: Mainly sunny. Light variable winds. Alpine high temperatures around -8.

Avalanche observations from Wednesday were limited to smaller (size 1-1.5) loose dry sluffs and small slabs releasing naturally from steep alpine features.On Monday, explosives triggered size 2 storm slab avalanches and cornices. Our 10-30 cm-deep weak layer of surface hoar was the failure plane.Skier-triggered, cornice-triggered, and natural storm slab avalanches were reported mainly on north-northeast aspects from 1700-2000 m over the weekend, including a snowboarder triggered a size 2 avalanche on a south aspect in open trees outside the Fernie boundary, fortunately with no injury. Two large snowmobile triggered avalanches were reported over a week ago. One was triggered on a thin, rocky, southwest facing feature near ridge crest north of Fernie (report here). The other was triggered on a wind affected south facing slope at treeline in the Corbin area (report here). Deep persistent slab activity has been most common in parts of the region with shallow snowpacks (such as near the continental divide) and alpine features with thin variable snowpack depths.

10-30 cm of badly wind-affected snow forms the current snow surface, the product of snowfall this past weekend and more recent strong and shifting winds. In alpine and treeline areas, winds have been redistributing this storm snow, loading lee terrain features, and building cornices. Lower down, the recent snow is sitting over a weak layer of surface hoar and sun crusts. The surface hoar is most prominent around treeline elevations (1500-1900 m) and is an increasing concern during the warming forecast in our region. On solar aspects and below treeline, the surface hoar and new snow overlie sun and temperature crusts.In shallow snowpack areas, the base of the snowpack may still be composed of weak faceted grains. In deeper snowpack areas, the middle and lower portions of the snowpack are generally considered to be well-settled and strong.