Avalanche Forecast

WEDNESDAY NIGHT: Increasing cloud, light wind increasing to strong southwest, alpine temperature -13.

THURSDAY: Scattered flurries, up to 5 cm snow, strong southwest overnight ridgetop wind easing to moderate, freezing level 1200 m.

FRIDAY: Scattered flurries, up to 5 cm new snow, light northwest wind, freezing level 1000 m.

SATURDAY: A mix of sun and cloud with isolated flurries, light to moderate northwest wind, freezing level 800 m.

Reports of storm slab avalanches from Monday and Tuesday near Golden include size 2-2.5 naturals, some of which were cornice triggered; size 2 explosive results; and skier triggered size 1s.

Near Invermere, natural, explosive and skier triggered wind slab avalanches were mainly in the 1-1.5 size range Monday and Tuesday. A natural size 2 wind slab on a northeast aspect is suspected to have stepped down to deeper persistent layers.

Earlier in February, there were a few reports of large avalanches (size 2.5-3) on southeast aspects in the alpine, likely releasing on a layer of facets on a crust (see a photo here), and a large human-triggered avalanche (size 2.5) on surface hoar near Quartz Creek.

Recent snowfall amounts have varied throughout the region from less than 10 cm in the east to 40-50 cm along the western border and near Golden. At upper elevations, this snow has been blown into thicker slabs in lee terrain features. 

The recent snow sits overtop of facetted surfaces from the cold snap. We expect this interface to stick around for a while. It will likely be a real head scratcher going forward, especially with such variability in overlying snow depths throughout the region. This MIN from one of the highest snowfall areas, gives a great account of spatial variability even on a small scale.

A weak layer that formed in late January is now 30-90 cm deep. In the northern Purcells this layer has been reported as a surface hoar layer at treeline and below, but a combination of facets or crusts could exist at all elevations. A couple of recent wind slab avalanches near Golden and Invermere have been suspected to have stepped down to this layer in the alpine.

The northern Purcells also have an older surface hoar layer that can still be found 60-120 cm deep at treeline. Additional weak layers may exist near the bottom of the snowpack and steep rocky areas with a shallow or thin to thick snowpack should be considered suspect trigger points.

• Choose slopes that are well supported and have limited consequence.
• Closely monitor how the new snow is bonding to the old surface.
• Be especially cautious as you transition into wind affected terrain.
• Avoid shallow, rocky areas where the snowpack transitions from thick to thin.