Avalanche Forecast

Issued: Feb 5th, 2017 4:52PM

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

Avalanche Canada jsmith, Avalanche Canada

Touchy storm slabs becoming more likely to trigger. Conservative decision making will be Critical to playing safe in the mountains on Monday.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain

Weather Forecast

Sunday night: 10-15 cm new snow / Moderate, southwesterly winds / Freezing level 900 m.Monday: 15-25 cm new snow / Moderate, southwesterly winds / Freezing level valley bottom.Tuesday: Mostly cloudy / Light to moderate, southwesterly winds / Freezing level valley bottom.Wednesday: Mostly cloudy with flurries / Light to moderate, southeasterly winds/ Freezing level valley bottom.

Avalanche Summary

On Saturday, numerous natural avalanches to size 1.5 and explosive triggered storm slab avalanches to size 3 were reported near Kootenay Pass. The fresh storm slabs were reported as being very reactive to human triggers throughout the region. Avalanche activity is expected to increase on Monday with the additional snow and wind.

Snowpack Summary

25-45 cm of recent storm snow has created touchy storm slabs at all elevations and aspects. Another 25-45 cm is expected by Monday evening bringing storm totals to 50-90 cm. Snowfall amounts are expected to be highest around Kootenay Pass and taper dramatically as you go north. These slabs have been reported as being very reactive to human triggers and are sitting on a variety of surfaces; including scoured surfaces in wind exposed terrain, surface hoar(size 2-3 mm) in sheltered locations, and sun crust on steep solar aspects. 40-70 cm of snow now overlies the weak layer of surface hoar(feathery crystals) and facets(sugar snow) that was buried in mid-January. There have been no recent reports of avalanches on this interface, but this may change with the increasing load. Areas with a shallower snowpack (less than 150 cm) have a generally weak snowpack structure with sugary facets near the ground. This includes shallow alpine slopes and most of the Rossland range. It is possible for storm slab avalanches to step-down to these deeper weak layers, resulting in large, destructive avalanches.

Problems

Storm Slabs

An icon showing Storm Slabs
Touchy storm slabs becoming more likely to trigger. Avoid avalanche terrain during periods of heavy loading by snow or wind.
Use small slopes with low consequence to test the bond of the new snow.Watch for signs of instability such as whumpfing, shotting cracks, or recent natural avalanching.Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 3

Persistent Slabs

An icon showing Persistent Slabs
Smaller storm slabs may step-down to deeper weak layers, resulting in large, destructive avalanches.
Dig down to find and test weak layers before committing to a line.Be aware of the potential for full depth avalanches due to weak layers at the base of the snowpack.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Feb 6th, 2017 2:00PM